/* ui.css: the Sophai design system. One section per piece, each opened by a "== <piece> ==" comment; the list of
   pieces is the index of these sections. Rules (test/ui-css-check.mjs): colours only in the token blocks (:root), weights at most 500
   (600 only on the citation chip), no !important, font-family only through the tokens, no font in data:.
   Read docs/UI.md before adding a piece. It holds the sign-in page (/login) and the whole student app (/): its shell,
   the conversation, the Curriculum Roadmap, the Bibliography, the Debug chat and the phone layout. */

/* == tokens == */
/* Light by default; dark when the system is dark and no light choice is saved, or when dark is saved. */
:root {
  color-scheme: light dark;
  --bg-page: #FAFAFB; --bg-primary: #FFFFFF; --bg-muted: #F2F2F4;
  --text-primary: #111113; --text-body: #3C3C43; --text-secondary: #646470; --text-faint: #9C9CA6;
  --accent: #7B6CF0; --link: #6A5BE0; --link-hover: #5F50D9; --on-accent: #FFFFFF;
  --soft-red-text: #C2413A;
  --hairline: rgba(17,17,19,.08); --edge-raised: rgba(17,17,19,.05);
  --font-body: 'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Source Serif 4', Georgia, serif;
  --text-xs: 12px; --text-sm: 13px; --text-md: 14px; --text-base: 15px; --text-input: 16px;
  --r-sm: 8px; --r: 12px; --r-lg: 16px;
  /* glass */
  --gl-read: rgba(255,255,255,.56); --gl-edge-a: rgba(255,255,255,.70); --gl-edge-b: rgba(255,255,255,.15);
  --gl-card: rgba(255,255,255,.5); --gl-card-edge: rgba(255,255,255,.8); --gl-hover: rgba(255,255,255,.6); --gl-press: rgba(255,255,255,.85);
  --isl-sheen: rgba(255,255,255,.9); --ctl-sheen: rgba(255,255,255,.18);
  --card-shadow: inset 0 1px 0 var(--isl-sheen), inset 0 -1px 2px rgba(0,0,0,.04), 0 1px 2px rgba(17,17,19,.05), 0 12px 32px rgba(70,50,160,.12), 0 18px 44px rgba(70,50,160,.16);
  --shadow-raised: 0 1px 2px rgba(17,17,19,.06), 0 4px 12px rgba(17,17,19,.04);
  --mask: #000;
  /* field */
  --field-bg: var(--bg-primary); --field-edge: var(--edge-raised);
  /* the accent's glow on the primary button */
  --accent-glow: 0 6px 18px rgba(123,108,240,.25), 0 1px 2px rgba(123,108,240,.2);
  --accent-glow-hi: 0 8px 22px rgba(123,108,240,.30), 0 1px 2px rgba(123,108,240,.2);
  /* the sign-in page's links: the darker violet keeps 4.5:1 on the glass over the aurora */
  --action-link: var(--link-hover);
  /* errors: the edge, the text (15-20 % of --text-primary keeps 4.5:1 on the glass) and the disc */
  --err-edge: var(--soft-red-text);
  --err-text: color-mix(in srgb, var(--soft-red-text) 80%, var(--text-primary));
  --err-bg: color-mix(in srgb, var(--soft-red-text) 12%, transparent);
  /* aurora (the sign-in page's strength) */
  --aurora-opacity: .52; --aur-blend: normal; --grain-opacity: .08; --dither-opacity: 0;
  --aur-1: radial-gradient(circle, rgba(124,94,232,.55) 0%, rgba(124,94,232,.36) 30%, rgba(124,94,232,.14) 55%, transparent 70%);
  --aur-2: radial-gradient(circle, rgba(128,90,178,.30) 0%, rgba(128,90,178,.2) 30%, rgba(128,90,178,.08) 55%, transparent 70%);
  --aur-3: radial-gradient(circle, rgba(80,92,190,.45) 0%, rgba(80,92,190,.3) 30%, rgba(80,92,190,.12) 55%, transparent 70%);
  --aur-dur: 90s; --aur-travel: 92vh; --br-a: 3.5; --br-t: 1.8;
  --ax: -34.6vw; --ay: 26.4vh;
  /* the dialog: its raised surface, the scrim (solid when transparency is reduced) and its shadows */
  --surface-raised: var(--bg-primary); --surface-raised-edge: var(--edge-raised);
  --scrim: rgba(17,17,19,.32); --scrim-solid: rgba(17,17,19,.5);
  --shadow-soft-lg: 0 18px 44px rgba(17,17,19,.09), 0 2px 4px rgba(17,17,19,.04);
  --shadow-sheet: 0 -12px 40px rgba(17,17,19,.12);
  /* the student app: a quiet fill (the phone drawer), the stronger divider, the accent's soft tint, the islands' shadow,
     the code font and the Debug chat's warning */
  --bg-subtle: #F7F7F9; --border-strong: #E0E0E3; --accent-soft: rgba(123,108,240,.08);
  --isl-shadow: 0 12px 32px rgba(70,50,160,.12), 0 1px 2px rgba(17,17,19,.05);
  --font-mono: ui-monospace, SFMono-Regular, Menlo, monospace;
  --warning: #B45309;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg-page: #0C0C0F; --bg-primary: #141417; --bg-muted: #202026;
    --text-primary: #F5F5F7; --text-body: #CDCDD5; --text-secondary: #A4A4B0; --text-faint: #5A5A64;
    --accent: #8B7CF6; --link: #8B7CF6; --link-hover: #9D90FF; --on-accent: #111113;
    --soft-red-text: #F08A84;
    --hairline: rgba(255,255,255,.08); --edge-raised: rgba(255,255,255,.07);
    --gl-read: rgba(20,20,24,.56); --gl-edge-a: rgba(255,255,255,.22); --gl-edge-b: rgba(255,255,255,.06);
    --gl-card: rgba(255,255,255,.06); --gl-card-edge: rgba(255,255,255,.1); --gl-hover: rgba(255,255,255,.08); --gl-press: rgba(255,255,255,.13);
    --isl-sheen: rgba(255,255,255,.12); --ctl-sheen: rgba(255,255,255,.14);
    --card-shadow: inset 0 1px 0 var(--isl-sheen), inset 0 -1px 2px rgba(0,0,0,.04), 0 1px 2px rgba(0,0,0,.4), 0 12px 32px rgba(0,0,0,.45);
    --shadow-raised: 0 1px 2px rgba(0,0,0,.45), 0 4px 12px rgba(0,0,0,.28);
    --field-bg: rgba(255,255,255,.06); --field-edge: rgba(255,255,255,.10);
    --accent-glow: 0 6px 20px rgba(139,124,246,.35), 0 1px 2px rgba(0,0,0,.4);
    --accent-glow-hi: 0 8px 22px rgba(139,124,246,.40), 0 1px 2px rgba(0,0,0,.4);
    --action-link: var(--link);
    --err-bg: color-mix(in srgb, var(--soft-red-text) 16%, transparent);
    --aurora-opacity: .85; --aur-blend: screen; --grain-opacity: .10; --dither-opacity: .09;
    --surface-raised: rgba(255,255,255,.10); --surface-raised-edge: rgba(255,255,255,.14);
    --scrim: rgba(0,0,0,.55); --scrim-solid: rgba(0,0,0,.7);
    --shadow-soft-lg: 0 18px 48px rgba(0,0,0,.55), 0 2px 4px rgba(0,0,0,.4);
    --shadow-sheet: 0 -12px 40px rgba(0,0,0,.6);
    --bg-subtle: #161619; --border-strong: #34343B; --accent-soft: rgba(139,124,246,.15);
    --isl-shadow: 0 12px 32px rgba(0,0,0,.45);
  }
}
:root[data-theme="light"] { color-scheme: light; }
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg-page: #0C0C0F; --bg-primary: #141417; --bg-muted: #202026;
  --text-primary: #F5F5F7; --text-body: #CDCDD5; --text-secondary: #A4A4B0; --text-faint: #5A5A64;
  --accent: #8B7CF6; --link: #8B7CF6; --link-hover: #9D90FF; --on-accent: #111113;
  --soft-red-text: #F08A84;
  --hairline: rgba(255,255,255,.08); --edge-raised: rgba(255,255,255,.07);
  --gl-read: rgba(20,20,24,.56); --gl-edge-a: rgba(255,255,255,.22); --gl-edge-b: rgba(255,255,255,.06);
  --gl-card: rgba(255,255,255,.06); --gl-card-edge: rgba(255,255,255,.1); --gl-hover: rgba(255,255,255,.08); --gl-press: rgba(255,255,255,.13);
  --isl-sheen: rgba(255,255,255,.12); --ctl-sheen: rgba(255,255,255,.14);
  --card-shadow: inset 0 1px 0 var(--isl-sheen), inset 0 -1px 2px rgba(0,0,0,.04), 0 1px 2px rgba(0,0,0,.4), 0 12px 32px rgba(0,0,0,.45);
  --shadow-raised: 0 1px 2px rgba(0,0,0,.45), 0 4px 12px rgba(0,0,0,.28);
  --field-bg: rgba(255,255,255,.06); --field-edge: rgba(255,255,255,.10);
  --accent-glow: 0 6px 20px rgba(139,124,246,.35), 0 1px 2px rgba(0,0,0,.4);
  --accent-glow-hi: 0 8px 22px rgba(139,124,246,.40), 0 1px 2px rgba(0,0,0,.4);
  --action-link: var(--link);
  --err-bg: color-mix(in srgb, var(--soft-red-text) 16%, transparent);
  --aurora-opacity: .85; --aur-blend: screen; --grain-opacity: .10; --dither-opacity: .09;
  --surface-raised: rgba(255,255,255,.10); --surface-raised-edge: rgba(255,255,255,.14);
  --scrim: rgba(0,0,0,.55); --scrim-solid: rgba(0,0,0,.7);
  --shadow-soft-lg: 0 18px 48px rgba(0,0,0,.55), 0 2px 4px rgba(0,0,0,.4);
  --shadow-sheet: 0 -12px 40px rgba(0,0,0,.6);
  --bg-subtle: #161619; --border-strong: #34343B; --accent-soft: rgba(139,124,246,.15);
  --isl-shadow: 0 12px 32px rgba(0,0,0,.45);
}
@media (max-width: 639px) { :root { --ax: -33.5vw; --ay: 10.8vh; } }

/* == fonts == */
/* Self-hosted (OFL, from sophai-brand): no request leaves the app. A changed file gets a new -vN name.
   Declared for 400 to 600: the weights the rules allow (600 only on the citation chip). */
@font-face { font-family: 'DM Sans'; font-style: normal; font-weight: 400 600; font-display: swap; src: url(/assets/fonts/dmsans-v1.woff2) format('woff2'); }
@font-face { font-family: 'Source Serif 4'; font-style: normal; font-weight: 400 600; font-display: swap; src: url(/assets/fonts/sourceserif4-opsz-v1.woff2) format('woff2'); }

/* == base == */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; min-height: 100vh; background: var(--bg-page); color: var(--text-body); font: 400 var(--text-base)/1.55 var(--font-body); -webkit-font-smoothing: antialiased; }
button, input { font: inherit; color: inherit; }
button { cursor: pointer; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
svg.i { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; flex: none; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
[hidden] { display: none; }

/* == aurora == */
/* Three colour blobs behind the content, fixed to the window, with a grain (and, in dark, a fine dither against
   banding). It drifts slowly and breathes; with prefers-reduced-motion it stands still. */
.sky-wrap { position: fixed; inset: 0; z-index: 0; overflow: hidden; pointer-events: none; }
.sky { position: absolute; inset: -10%; opacity: var(--aurora-opacity); filter: blur(46px) saturate(1.15);
  transform: translate3d(var(--ax), var(--ay), 0); animation: aur-drift var(--aur-dur) ease-in-out infinite alternate; will-change: transform; }
.sky i { position: absolute; display: block; border-radius: 50%; mix-blend-mode: var(--aur-blend); }
.sky .b1 { width: 50%; height: 62%; left: 54%; top: -14%; background: var(--aur-1); animation: br1 calc(16s * var(--br-t)) ease-in-out infinite alternate; }
.sky .b2 { width: 40%; height: 50%; left: 68%; top: 8%; background: var(--aur-2); animation: br2 calc(19s * var(--br-t)) ease-in-out infinite alternate; }
.sky .b3 { width: 46%; height: 56%; left: 44%; top: -22%; background: var(--aur-3); animation: br3 calc(17s * var(--br-t)) ease-in-out infinite alternate; }
@keyframes aur-drift { from { transform: translate3d(var(--ax), var(--ay), 0); } to { transform: translate3d(var(--ax), calc(var(--ay) + var(--aur-travel)), 0); } }
@keyframes br1 { 0% { transform: none; } 50% { transform: translate3d(calc(-6% * var(--br-a)), calc(6% * var(--br-a)), 0) scale(calc(1 + .1 * var(--br-a))); } 100% { transform: translate3d(calc(4% * var(--br-a)), calc(8% * var(--br-a)), 0) scale(calc(1 + .04 * var(--br-a))); } }
@keyframes br2 { 0% { transform: none; } 50% { transform: translate3d(calc(-8% * var(--br-a)), calc(-4% * var(--br-a)), 0) scale(calc(1 + .1 * var(--br-a))); } 100% { transform: translate3d(calc(4% * var(--br-a)), calc(-6% * var(--br-a)), 0) scale(calc(1 + .02 * var(--br-a))); } }
@keyframes br3 { 0% { transform: none; } 50% { transform: translate3d(calc(6% * var(--br-a)), calc(5% * var(--br-a)), 0) scale(calc(1 - .05 * var(--br-a))); } 100% { transform: translate3d(calc(-5% * var(--br-a)), calc(3% * var(--br-a)), 0) scale(calc(1 + .08 * var(--br-a))); } }
.sky-wrap::before { content: ""; position: absolute; inset: 0; z-index: 1; pointer-events: none; opacity: var(--dither-opacity); background-size: 96px 96px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='96' height='96'%3E%3Cfilter id='d' color-interpolation-filters='sRGB'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='1.6' numOctaves='1' stitchTiles='stitch'/%3E%3CfeColorMatrix values='.33 .33 .33 0 0  .33 .33 .33 0 0  .33 .33 .33 0 0  0 0 0 0 1'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23d)'/%3E%3C/svg%3E"); }
.sky-wrap::after { content: ""; position: absolute; inset: 0; opacity: var(--grain-opacity); background-size: 200px 200px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E"); }
/* the blobs are named as specifically as their own animation rules above, or those would win */
@media (prefers-reduced-motion: reduce) { .sky, .sky .b1, .sky .b2, .sky .b3 { animation: none; } }

/* == glass card == */
/* The glass island over the aurora: a translucent fill, blur 16 with saturate 180 %, a 1 px edge fading from the
   top left, the top sheen and the island's shadow. Without transparency it turns solid. */
.glass-card { position: relative; border-radius: var(--r-lg); background: var(--gl-read);
  -webkit-backdrop-filter: blur(16px) saturate(180%); backdrop-filter: blur(16px) saturate(180%); box-shadow: var(--card-shadow); }
.glass-card::after { content: ""; position: absolute; inset: 0; border-radius: inherit; padding: 1px; pointer-events: none; background: linear-gradient(135deg, var(--gl-edge-a), var(--gl-edge-b));
  -webkit-mask: linear-gradient(var(--mask) 0 0) content-box, linear-gradient(var(--mask) 0 0); -webkit-mask-composite: xor;
  mask: linear-gradient(var(--mask) 0 0) content-box exclude, linear-gradient(var(--mask) 0 0); }
@media (prefers-reduced-transparency: reduce) { .glass-card { background: var(--bg-primary); -webkit-backdrop-filter: none; backdrop-filter: none; box-shadow: inset 0 0 0 1px var(--edge-raised); } .glass-card::after { display: none; } }
@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) { .glass-card { background: var(--bg-primary); box-shadow: inset 0 0 0 1px var(--edge-raised); } .glass-card::after { display: none; } }

/* == field == */
/* A label of 13/500 above a 48 px box with the field's surface; .error gives a 2 px edge in the error colour. */
.fld { display: flex; flex-direction: column; gap: 8px; }
.fld-l { font: 500 var(--text-sm)/1.3 var(--font-body); color: var(--text-secondary); transition: color .12s ease-out; }
.fld:focus-within .fld-l { color: var(--text-primary); }
.fld-i { width: 100%; height: 48px; padding: 0 16px; border: 0; border-radius: var(--r); background: var(--field-bg); box-shadow: inset 0 0 0 1px var(--field-edge);
  font: 400 var(--text-input)/1.4 var(--font-body); color: var(--text-primary); outline: none; transition: box-shadow .12s ease-out, background-color .12s ease-out; }
.fld-i::placeholder { color: var(--text-body); opacity: .7; }
.fld-i:focus, .fld-i:focus-visible { outline: 2px solid var(--accent); outline-offset: 0; }
@media (hover: hover) { .fld-i:not(.error):hover:not(:disabled) { box-shadow: inset 0 0 0 1px var(--hairline); } }
.fld-i:disabled { opacity: .6; cursor: default; }
.fld-i.error { box-shadow: inset 0 0 0 2px var(--err-edge); }
.fld-i.error:focus, .fld-i.error:focus-visible { outline: 2px solid var(--err-edge); box-shadow: inset 0 0 0 1px var(--field-edge); }
.fld-i.code { font: 500 20px/1.2 var(--font-body); letter-spacing: .1em; font-variant-numeric: tabular-nums; }
.fld-i.code::selection { background: color-mix(in srgb, var(--accent) 25%, transparent); }

/* == buttons == */
/* Primary: 48 px, the link violet with a sheen and a glow. Secondary: the glass key. Action link: text only, a 44 px
   target on touch screens. */
.btn-pri, .btn-sec { display: flex; align-items: center; justify-content: center; width: 100%; height: 48px; margin: 0; padding: 0 16px; border: 0; border-radius: var(--r);
  font: 500 var(--text-base)/1 var(--font-body); }
.btn-pri { background: var(--link); color: var(--on-accent); box-shadow: inset 0 1px 0 var(--ctl-sheen), var(--accent-glow); transition: background-color .15s, box-shadow .15s, transform .1s; }
.btn-pri:hover:not(:disabled) { background: var(--link-hover); box-shadow: inset 0 1px 0 var(--ctl-sheen), var(--accent-glow-hi); }
.btn-pri:active:not(:disabled) { transform: translateY(1px); box-shadow: inset 0 1px 0 var(--ctl-sheen), var(--accent-glow); }
.btn-pri:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; box-shadow: 0 0 0 2px var(--bg-primary), inset 0 1px 0 var(--ctl-sheen), var(--accent-glow); }
.btn-pri:disabled { opacity: .7; cursor: default; }
.btn-sec { background: var(--gl-card); color: var(--text-body); box-shadow: inset 0 0 0 1px var(--gl-card-edge), inset 0 1px 0 var(--ctl-sheen); transition: background-color .15s, box-shadow .15s, color .15s; }
.btn-sec:hover:not(:disabled) { background: var(--gl-hover); box-shadow: inset 0 0 0 1px var(--gl-card-edge), inset 0 1px 0 var(--ctl-sheen), var(--shadow-raised); }
.btn-sec:active:not(:disabled) { background: var(--gl-press); }
.btn-sec:disabled { color: var(--text-secondary); cursor: default; }
.btn-link { align-self: center; min-height: 32px; margin: 0; padding: 0 8px; border: 0; border-radius: var(--r-sm); background: none;
  font: 500 var(--text-md)/1.3 var(--font-body); color: var(--action-link); text-decoration: none; text-underline-offset: 3px; text-decoration-thickness: 1px; transition: color .12s; }
.btn-link:hover:not(:disabled), .btn-link:focus-visible { text-decoration: underline; }
.btn-link:disabled { opacity: .5; cursor: default; }
@media (max-width: 1024px), (pointer: coarse) { .btn-link { min-height: 44px; min-width: 44px; } }

/* == error notice == */
/* A disc with the icon, the first sentence at 500 in the error colour, the rest in --text-body. Empty, it keeps no
   height but stays in the page (role="alert" must be there before the message arrives). */
.err-note { display: grid; grid-template-columns: 28px minmax(0, 1fr); align-items: center; gap: 10px; padding: 10px 14px 10px 10px; border-radius: 14px;
  background: var(--err-bg); box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--err-text) 22%, transparent); }
.err-note:empty { padding: 0; background: none; box-shadow: none; }
.err-note > svg.i { box-sizing: border-box; width: 28px; height: 28px; padding: 6px; border-radius: 50%; stroke-width: 2.5; background: var(--err-bg); color: var(--err-text); }
.err-note > span { font: 400 var(--text-md)/1.4 var(--font-body); color: var(--text-body); overflow-wrap: anywhere; }
.err-note b { font-weight: 500; color: var(--err-text); }

/* == login == */
/* The sign-in page: the glass card centred over the aurora, the wordmark, the two steps (email, then code). */
.lg-wrap { position: relative; z-index: 1; min-height: 100vh; min-height: 100dvh; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 24px; padding: 32px 16px; }
.lg-card { width: min(360px, 100%); padding: 32px; display: flex; flex-direction: column; gap: 32px; overflow-wrap: anywhere; animation: lg-rise .15s ease-out both; }
.lg-card > * { position: relative; z-index: 1; }
@keyframes lg-rise { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
.lg-brand { display: flex; flex-direction: column; align-items: center; text-align: center; }
.lg-wm-h { margin: 4px 0 0; line-height: 0; }
.lg-wm { display: block; width: 160px; height: auto; }
/* the wordmark follows the theme: the light file, or the night one in dark (a saved choice wins over the system) */
.lg-wm-dark { display: none; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .lg-wm-light { display: none; } :root:not([data-theme="light"]) .lg-wm-dark { display: block; } }
:root[data-theme="dark"] .lg-wm-light { display: none; }
:root[data-theme="dark"] .lg-wm-dark { display: block; }
.lg-sub { margin: 19px 0 0; font: 400 var(--text-base)/1.4 var(--font-body); color: var(--text-secondary); }
.err-note:not(:empty) { margin-bottom: 16px; }
.lg-step { display: flex; flex-direction: column; margin: 0; }
.lg-step[hidden] { display: none; }
.lg-step > * + * { margin-top: 16px; }
.lg-step > .btn-pri + .resend-row, .lg-step > .btn-link + .lg-note { margin-top: 8px; }
/* the card that says where the code went */
.lg-sent { display: grid; grid-template-columns: 18px minmax(0, 1fr); column-gap: 12px; align-items: start; padding: 12px 14px; border-radius: var(--r);
  background: color-mix(in srgb, var(--accent) 7%, transparent); }
.lg-sent > svg.i { margin-top: 2px; color: var(--accent); }
.lg-sent-txt { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.lg-to { margin: 0; font: 400 var(--text-base)/1.4 var(--font-body); color: var(--text-primary); overflow-wrap: anywhere; }
.lg-to strong { font-weight: 500; }
.lg-msg { margin: 0; font: 400 var(--text-sm)/1.4 var(--font-body); color: var(--text-body); }
/* Send a new code, with the wait's clock inside the key */
.resend-row { position: relative; }
.resend-wait { position: absolute; right: 16px; top: 50%; transform: translateY(-50%); pointer-events: none; font: 400 var(--text-base)/1 var(--font-body); font-variant-numeric: tabular-nums; color: var(--text-secondary); }
.lg-note { align-self: center; max-width: 296px; margin: 0; font: 400 var(--text-sm)/1.45 var(--font-body); color: var(--text-secondary); text-align: center; }
/* the legal line, under the card over the aurora: 12/400, links underlined lightly in the text's colour (legal links
   are exempt from the 44 px touch rule). --text-body, not --text-secondary: on the light aurora's violet the
   secondary grey gave 4.1:1, under the 4.5:1 the line needs. */
.lg-legal { max-width: 480px; margin: 0; font: 400 var(--text-xs)/1.5 var(--font-body); color: var(--text-body); text-align: center; animation: lg-rise .15s ease-out .06s both; }
.lg-legal a { color: inherit; text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 2px; }
@media (max-width: 639px) {
  .lg-wrap { padding: 12vh 16px 32px; justify-content: flex-start; }
  .lg-card { padding: 24px; gap: 24px; }
  .lg-wm { width: 128px; }
  .lg-sub { margin-top: 13px; }
}
@media (prefers-reduced-motion: reduce) { .lg-card, .lg-legal { animation: none; } .lg-card *, .lg-card *::before, .lg-card *::after { transition: none; } }

/* == dialog == */
/* A modal that asks before going on: a scrim (blurred 12) under a solid raised panel, radius 16, padding 24; the glyph
   disc of 40, the title 18/500, the text 15/1.5 in --text-secondary, then the actions on the right: 44 high, radius 10,
   the cancel outlined, the main one filled (grey while disabled). Measures in px, never the size tokens a page may
   redefine. The page makes the rest inert and decides what Escape does. On the phone (< 640) it is a sheet against the
   bottom, the disc and the texts centred, the buttons stacked at 48 with the main one on top. Opening: the scrim fades in
   and the panel rises 8 (24 on the phone); the panel itself never starts transparent, so what it says is legible from
   the first frame.
   .dlg-terms: the Terms window ("Antes de começar"), 440 wide, with no grabber (it cannot be closed); the boxes
   (checkbox) sit between the text and the actions; an error notice (error notice) goes above the boxes, at 14 px. */
.dlg-scrim { position: fixed; inset: 0; z-index: 4500; background: var(--scrim); -webkit-backdrop-filter: blur(12px) saturate(120%); backdrop-filter: blur(12px) saturate(120%);
  animation: dlg-fade .15s ease-out both; }
@media (prefers-reduced-transparency: reduce) { .dlg-scrim { background: var(--scrim-solid); -webkit-backdrop-filter: none; backdrop-filter: none; } }
@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) { .dlg-scrim { background: var(--scrim-solid); } }
.dlg { position: fixed; inset: 0; z-index: 4600; display: grid; place-items: center; padding: 16px; pointer-events: none; }
.dlg-scrim[hidden], .dlg[hidden] { display: none; }
.dlg-panel { pointer-events: auto; display: flex; flex-direction: column; width: min(400px, 100%); max-height: calc(100vh - 32px); overflow: auto; padding: 24px; border-radius: 16px;
  background: linear-gradient(var(--surface-raised), var(--surface-raised)), var(--bg-primary); box-shadow: var(--shadow-soft-lg), inset 0 0 0 1px var(--surface-raised-edge);
  font: 400 15px/1.5 var(--font-body); color: var(--text-body); overflow-wrap: anywhere; animation: dlg-in .15s ease-out both; }
.dlg-terms { width: min(440px, 100%); }
.dlg-panel > * { margin: 0; }
.dlg-g { display: grid; place-items: center; flex: none; width: 40px; height: 40px; margin: 0 0 16px; border-radius: 50%; background: color-mix(in srgb, var(--accent) 12%, transparent); color: var(--link-hover); }
.dlg-g > svg.i { width: 20px; height: 20px; }
.dlg-panel > .dlg-t { font: 500 18px/1.3 var(--font-body); letter-spacing: -.01em; color: var(--text-primary); text-align: left; }
.dlg-panel > .dlg-d { margin-top: 8px; font: 400 15px/1.5 var(--font-body); color: var(--text-secondary); text-align: left; }
.dlg-d a { color: var(--link); text-decoration: underline; text-underline-offset: 2px; }
.dlg-panel > .cb-row { margin-top: 24px; }
.dlg-panel > .cb-row + .cb-row { margin-top: 8px; }
/* the error notice inside the panel: 14 px (the page may redefine --text-md), and its action, a raised button of 32 */
.dlg-panel > .err-note { margin: 24px 0 0; }
.dlg-panel > .err-note:empty { margin: 0; }
.dlg-panel > .err-note > span { font-size: 14px; }
.dlg-panel .err-act { grid-column: 2; justify-self: start; position: relative; display: inline-flex; align-items: center; height: 32px; margin-top: 6px; padding: 0 12px; border: 0; border-radius: 10px;
  background: var(--surface-raised); box-shadow: inset 0 0 0 1px var(--hairline), var(--shadow-raised); font: 500 14px/1.3 var(--font-body); color: var(--text-primary); transition: background-color .15s; }
.dlg-panel .err-act:hover { background: linear-gradient(color-mix(in srgb, var(--text-primary) 5%, transparent), color-mix(in srgb, var(--text-primary) 5%, transparent)), var(--surface-raised); }
.dlg-panel .err-act::after { content: ""; position: absolute; left: 0; right: 0; top: 50%; height: 44px; transform: translateY(-50%); }
.dlg-acts { margin-top: 24px; display: flex; justify-content: flex-end; gap: 8px; }
.dlg-btn { position: relative; height: 44px; padding: 0 18px; border: 0; border-radius: 10px; font: 500 15px/1.2 var(--font-body); text-align: center;
  transition: background-color .15s, box-shadow .15s, transform .1s; }
.dlg-btn::after { content: ""; position: absolute; left: 50%; top: 50%; width: max(100%, 44px); height: 44px; transform: translate(-50%, -50%); }
.dlg-btn:active:not(:disabled) { transform: translateY(1px); }
.dlg-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.dlg-cancel { background: transparent; box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--text-primary) 16%, transparent); color: var(--text-primary); }
.dlg-cancel:hover { background: color-mix(in srgb, var(--text-primary) 5%, transparent); }
.dlg-ok { background: var(--link); color: var(--on-accent); box-shadow: inset 0 1px 0 var(--ctl-sheen), var(--accent-glow); }
.dlg-ok:hover:not(:disabled) { background: var(--link-hover); }
/* disabled: grey, its text a little darker than --text-secondary so it keeps 4.5:1 on --bg-muted */
.dlg-ok:disabled { background: var(--bg-muted); color: color-mix(in srgb, var(--text-secondary) 80%, var(--text-primary)); box-shadow: none; cursor: default; }
/* dark: the raised surface is lighter, so its links take the lighter violet */
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .dlg-d a { color: var(--link-hover); } }
:root[data-theme="dark"] .dlg-d a { color: var(--link-hover); }
@keyframes dlg-fade { from { opacity: 0; } }
@keyframes dlg-in { from { transform: translateY(8px); } }
@keyframes dlg-up { from { transform: translateY(24px); } }
@media (max-width: 639px) {
  .dlg { place-items: end stretch; padding: 0; }
  .dlg-panel { width: 100%; max-height: 86vh; border-radius: 16px 16px 0 0; padding: 24px 24px max(24px, calc(env(safe-area-inset-bottom) + 16px));
    box-shadow: var(--shadow-sheet), inset 0 1px 0 var(--hairline); animation: dlg-up .2s ease-out both; }
  .dlg-g { margin: 0 auto 16px; }
  .dlg-panel > .dlg-t, .dlg-panel > .dlg-d { text-align: center; }
  .dlg-acts { flex-direction: column-reverse; }
  .dlg-btn { width: 100%; height: 48px; border-radius: 12px; }
}
@media (prefers-reduced-motion: reduce) { .dlg-scrim, .dlg-panel { animation: none; } .dlg-panel *, .dlg-panel *::before, .dlg-panel *::after { transition: none; } }

/* == checkbox == */
/* A row of 56 with the field's surface: a real checkbox, visually hidden, behind a box of 20 (radius 6) that fills with
   the accent when checked, the check popping in; the text 15/1.4. The whole row is the label and carries the focus
   ring. A link inside the text opens its page and leaves the box as it was. Disabled, the box fades to half. */
.cb-row { position: relative; display: grid; grid-template-columns: 20px minmax(0, 1fr); gap: 12px; align-items: center; min-height: 56px; padding: 0 16px; border-radius: 12px;
  background: var(--field-bg); box-shadow: inset 0 0 0 1px var(--field-edge); cursor: pointer; transition: background-color .12s, box-shadow .12s; }
.cb-i { position: absolute; left: 16px; top: 50%; width: 1px; height: 1px; margin: 0; padding: 0; border: 0; opacity: 0; overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap; }
.cb { display: grid; place-items: center; width: 20px; height: 20px; border-radius: 6px; background: var(--bg-primary);
  box-shadow: inset 0 0 0 1.5px color-mix(in srgb, var(--text-secondary) 70%, transparent); transition: background-color .15s, box-shadow .15s; }
.cb > svg.i { width: 14px; height: 14px; stroke-width: 2.5; color: var(--on-accent); opacity: 0; transform: scale(.6); transition: opacity .12s, transform .18s cubic-bezier(.3, .8, .3, 1.4); }
.cb-row:has(.cb-i:checked) { background: color-mix(in srgb, var(--accent) 7%, transparent); box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--accent) 40%, transparent); }
.cb-row:has(.cb-i:checked) .cb { background: var(--accent); box-shadow: inset 0 1px 0 var(--ctl-sheen), 0 1px 2px color-mix(in srgb, var(--accent) 35%, transparent); }
.cb-row:has(.cb-i:checked) .cb > svg.i { opacity: 1; transform: none; }
@media (hover: hover) { .cb-row:not(:has(.cb-i:disabled)):not(:has(.cb-i:checked)):hover { background: linear-gradient(color-mix(in srgb, var(--text-primary) 4%, transparent), color-mix(in srgb, var(--text-primary) 4%, transparent)), var(--field-bg); } }
.cb-row:not(:has(.cb-i:disabled)):active { background: linear-gradient(color-mix(in srgb, var(--text-primary) 8%, transparent), color-mix(in srgb, var(--text-primary) 8%, transparent)), var(--field-bg); transition-duration: .1s; }
.cb-row:has(.cb-i:focus-visible) { outline: 2px solid var(--accent); outline-offset: 0; }
.cb-row:has(.cb-i:disabled) { cursor: default; }
.cb-row:has(.cb-i:disabled) .cb { opacity: .5; }
.cb-t { font: 400 15px/1.4 var(--font-body); color: var(--text-primary); }
.cb-t a { position: relative; color: var(--link); text-decoration: underline; text-underline-offset: 2px; }
.cb-t a::after { content: ""; position: absolute; left: 0; right: 0; top: 50%; height: 44px; transform: translateY(-50%); }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .cb-t a { color: var(--text-primary); text-decoration-color: var(--link-hover); } }
:root[data-theme="dark"] .cb-t a { color: var(--text-primary); text-decoration-color: var(--link-hover); }
@media (prefers-reduced-motion: reduce) { .cb-row, .cb, .cb > svg.i { transition: none; } }

/* == shell == */
/* The student app (/). .app is the root, as tall as the window (100dvh, the viewport resizes with the keyboard): a grid
   of the left bar, the main column and the right column, which holds the icon bar (64) or, from 1280 with the panel
   open, the panel too (320 + 72). The aurora sits behind it all; the island #topbar floats over the main column, the
   icon bar and the panel over the right column. On the phone (== phone ==) one column. */
.app-page { height: 100dvh; min-height: 0; overflow: hidden; }
.app { --lb-w: clamp(240px, 20vw, 300px); --rc-w: 64px;
  position: relative; isolation: isolate; display: grid; grid-template-columns: var(--lb-w) minmax(0, 1fr) var(--rc-w); grid-template-rows: minmax(0, 1fr);
  height: 100vh; height: 100dvh; overflow: hidden; }
@media (min-width: 1280px) { .app.panel-open { --rc-w: 392px; } }
.icon-btn { display: inline-grid; place-items: center; justify-content: center; align-items: center; flex: none; width: 32px; height: 32px; margin: 0; padding: 0; border: 0; border-radius: var(--r-sm);
  background: none; color: var(--text-secondary); text-decoration: none; transition: background-color .12s, color .12s; }
.icon-btn:hover { background: var(--bg-muted); color: var(--text-primary); }
.icon-btn:focus-visible { outline-offset: 0; }
/* the brand files follow the theme: the light page shows the light file, dark the night one */
.lb-wm.lb-dark, .isl-sym .lb-dark, .lb-sym { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .lb-wm.lb-light, :root:not([data-theme="light"]) .isl-sym .lb-light { display: none; }
  :root:not([data-theme="light"]) .lb-wm.lb-dark, :root:not([data-theme="light"]) .isl-sym .lb-dark { display: block; }
}
:root[data-theme="dark"] .lb-wm.lb-light, :root[data-theme="dark"] .isl-sym .lb-light { display: none; }
:root[data-theme="dark"] .lb-wm.lb-dark, :root[data-theme="dark"] .isl-sym .lb-dark { display: block; }

/* the left bar: the wordmark and Collapse menu in a row of 56, Tools, then Send feedback and the account at the bottom */
.leftbar { grid-column: 1; grid-row: 1; position: relative; z-index: 20; display: flex; flex-direction: column; min-width: 0; min-height: 0; padding: 0 16px 16px;
  background: var(--gl-read); -webkit-backdrop-filter: blur(20px) saturate(150%); backdrop-filter: blur(20px) saturate(150%); box-shadow: inset -1px 0 0 var(--hairline); }
.lb-head { display: flex; align-items: center; justify-content: space-between; gap: 8px; flex: none; height: 56px; margin: 0 0 8px; }
.lb-brand { display: flex; align-items: center; height: 40px; margin: 0; padding: 0 8px; border: 0; border-radius: var(--r-sm); background: none; color: inherit; }
.lb-brand:hover { background: var(--bg-muted); }
.lb-wm { display: block; width: 88px; height: auto; }
.lb-sym { width: 36px; height: 36px; }
.lb-close { display: none; }
.lb-tools { display: flex; flex-direction: column; gap: 4px; flex: none; }
.lb-sec { display: flex; align-items: center; height: 32px; margin: 0; padding: 0 8px; font: 500 var(--text-sm)/1 var(--font-body); color: var(--text-secondary); }
.lb-item { display: flex; align-items: center; gap: 12px; width: 100%; height: 48px; margin: 0; padding: 0 8px; border: 0; border-radius: 10px; background: none;
  font: 500 var(--text-base)/1.2 var(--font-body); color: var(--text-body); text-align: left; transition: background-color .12s, color .12s; }
.lb-item:hover { background: var(--bg-muted); color: var(--text-primary); }
.lb-item:focus-visible { outline-offset: 0; }
.lb-item[aria-current="page"] { background: var(--bg-primary); color: var(--text-primary); box-shadow: var(--shadow-raised), inset 0 0 0 1px var(--edge-raised); }
/* the tool's app tile, in relief; only the chosen tool is tinted violet */
.lb-tile { display: grid; place-items: center; flex: none; width: 32px; height: 32px; border-radius: var(--r-sm); color: var(--text-secondary);
  background: linear-gradient(to bottom, var(--bg-primary), var(--bg-muted)); box-shadow: inset 0 1px 0 var(--isl-sheen), 0 1px 2px var(--edge-raised), 0 0 0 1px var(--edge-raised); }
.lb-item[aria-current="page"] .lb-tile { color: var(--accent); background: linear-gradient(to bottom, var(--bg-primary), var(--accent-soft)); }
.lb-label { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.lb-foot { display: flex; flex-direction: column; gap: 8px; margin-top: auto; padding-top: 8px; }
/* Send feedback: an action card on the glass, ↗ because it opens another tab */
.lb-feedback { align-items: center; gap: 8px; min-height: 48px; padding: 8px; border-radius: 10px; background: var(--gl-card);
  box-shadow: inset 0 0 0 1px var(--gl-card-edge), var(--shadow-raised); color: var(--text-secondary); text-decoration: none; transition: background-color .15s, transform .15s; }
.lb-feedback:hover { background: var(--gl-hover); transform: translateY(-1px); }
.lb-feedback:active { background: var(--gl-press); transform: none; }
.lb-fb-text { display: flex; flex-direction: column; gap: 1px; min-width: 0; }
.feedback-label { font: 500 var(--text-base)/1.3 var(--font-body); color: var(--text-body); }
.feedback-sub { font: 400 var(--text-sm)/1.3 var(--font-body); color: var(--text-secondary); }
.lb-feedback > .lb-fb-go { width: 16px; height: 16px; margin-left: auto; }
.lb-acct { display: flex; align-items: center; gap: 4px; min-width: 0; }
.lb-acct > .account-menu { flex: 1 1 auto; min-width: 0; }
.lb-admin { width: 48px; height: 48px; border-radius: 10px; }

/* the main column: the island over the screen that is open */
.main { grid-column: 2; grid-row: 1; position: relative; z-index: 1; display: flex; flex-direction: column; min-width: 0; min-height: 0; }
.island { background: var(--gl-read); -webkit-backdrop-filter: blur(20px) saturate(150%); backdrop-filter: blur(20px) saturate(150%); border-radius: var(--r-lg);
  box-shadow: inset 0 0 0 1px var(--gl-card-edge), inset 0 1px 0 var(--isl-sheen), var(--isl-shadow); }
@media (prefers-reduced-transparency: reduce) { .island { background: var(--bg-primary); -webkit-backdrop-filter: none; backdrop-filter: none; box-shadow: 0 0 0 1px var(--hairline), var(--shadow-raised); } }
.topbar { position: absolute; top: 8px; left: 24px; z-index: 10; display: flex; align-items: center; gap: 4px; max-width: calc(100% - 48px); min-height: 40px; padding: 4px; }
.isl-btn { display: none; place-items: center; flex: none; width: 44px; height: 44px; margin: 0; padding: 0; border: 0; border-radius: 14px; background: none; color: var(--text-body); }
.isl-btn:active { background: var(--gl-press); }
.isl-btn:focus-visible { outline-offset: 0; }
.isl-sym img { width: 32px; height: 32px; }
.path { display: flex; align-items: center; min-width: 0; flex: 1 1 auto; padding: 0 8px; }
.course-name { min-width: 0; white-space: nowrap; font: 500 var(--text-md)/1.2 var(--font-body); color: var(--text-primary); }
/* 2 or more courses: the name is a button with the ▾ (#course-btn) that opens My courses, a menu of solid surface */
.path { position: relative; }
.course-btn { display: inline-flex; align-items: center; gap: 8px; max-width: 100%; height: 32px; margin: 0; padding: 0 8px; border: 0; border-radius: var(--r); background: none;
  font: 500 var(--text-base)/1.2 var(--font-body); color: var(--text-primary); transition: background-color .15s, box-shadow .15s; }
.course-btn:hover { background: var(--bg-muted); }
.course-btn[aria-expanded="true"] { background: var(--bg-primary); box-shadow: var(--shadow-raised), inset 0 0 0 1px var(--edge-raised); }
.course-btn:disabled { opacity: .7; cursor: default; }
.course-btn:focus-visible { outline-offset: 0; }
.course-btn svg.i { width: 16px; height: 16px; color: var(--text-secondary); }
.course-txt { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.course-btn .course-chev { margin-left: -4px; transition: transform .15s; }
.course-btn[aria-expanded="true"] .course-chev { transform: rotate(180deg); color: var(--text-primary); }
.course-menu { position: absolute; top: calc(100% + 6px); left: 0; z-index: 60; width: min(340px, calc(100vw - 16px)); max-height: min(520px, calc(100dvh - 80px)); overflow: auto;
  padding: 8px; border-radius: var(--r-lg); background: var(--bg-primary); box-shadow: inset 0 1px 0 var(--isl-sheen), var(--shadow-soft-lg), 0 0 0 1px var(--hairline); }
.course-menu-head { margin: 0; padding: 8px 10px 4px; font: 500 var(--text-sm)/1.3 var(--font-body); color: var(--text-secondary); }
.course-opt { display: flex; align-items: center; gap: 10px; width: 100%; min-height: 40px; margin: 0; padding: 6px 10px; border: 0; border-radius: var(--r); background: none;
  font: 400 var(--text-md)/1.3 var(--font-body); color: var(--text-body); text-align: left; }
.course-opt:hover, .course-opt:focus-visible { background: var(--bg-muted); color: var(--text-primary); }
.course-opt:focus-visible { outline-offset: -2px; }
.course-opt[aria-checked="true"] { background: var(--accent-soft); color: var(--text-primary); font-weight: 500; }
.course-opt-name { flex: 1 1 auto; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.course-ck { display: none; color: var(--accent); }
@media (prefers-reduced-motion: reduce) { .course-btn, .course-btn .course-chev { transition: none; } }
.offline-banner { position: absolute; top: 56px; left: 24px; right: 24px; z-index: 9; margin: 0; padding: 10px 14px; border-radius: var(--r); background: var(--bg-primary);
  box-shadow: inset 0 0 0 1px var(--hairline), var(--shadow-raised); font: 500 var(--text-md)/1.4 var(--font-body); color: var(--text-primary); }
/* the screens: one shown at a time */
.screen { position: relative; display: flex; flex-direction: column; flex: 1 1 auto; min-height: 0; }
.page { flex: 1 1 auto; min-height: 0; overflow-y: auto; padding: 88px 16px 32px; }
.page > * { max-width: 720px; margin-left: auto; margin-right: auto; }
.page-title { margin-top: 0; margin-bottom: 16px; font: 400 28px/1.2 var(--font-serif); letter-spacing: -.01em; color: var(--text-primary); }
.empty-placeholder { padding: 24px 12px; font: 400 var(--text-sm)/1.6 var(--font-body); color: var(--text-secondary); text-align: center; }
.empty-placeholder a { color: inherit; }

/* the icon bar and the panel (glass islands at 8 from the edge; the panel 8 to the left of the bar) */
.panel-bar { position: absolute; top: 8px; right: 8px; z-index: 15; display: flex; flex-direction: column; gap: 4px; width: 40px; padding: 4px; }
.pb-btn { display: grid; place-items: center; width: 32px; height: 32px; margin: 0; padding: 0; border: 0; border-radius: 12px; background: none; color: var(--text-secondary);
  transition: background-color .12s, color .12s; }
.pb-btn:hover { background: var(--bg-muted); color: var(--text-primary); }
.pb-btn:focus-visible { outline-offset: 0; }
.pb-btn[aria-pressed="true"] { background: var(--bg-primary); color: var(--accent); box-shadow: var(--shadow-raised), inset 0 0 0 1px var(--edge-raised); }
.panel { position: absolute; top: 8px; right: 56px; bottom: 8px; z-index: 15; display: flex; flex-direction: column; width: 320px; min-height: 0; overflow: hidden;
  border-radius: var(--r-lg); background: var(--gl-read); -webkit-backdrop-filter: blur(20px) saturate(150%); backdrop-filter: blur(20px) saturate(150%);
  box-shadow: inset 0 0 0 1px var(--gl-card-edge), inset 0 1px 0 var(--isl-sheen), var(--isl-shadow); }
@media (prefers-reduced-transparency: reduce) { .panel { background: var(--bg-primary); -webkit-backdrop-filter: none; backdrop-filter: none; } }
.panel-tabs { display: none; }
/* header E5: the tool's name on a small line, the view's title 17/500, then Expand panel and Close panel (32) */
.panel-head { display: flex; align-items: flex-start; gap: 4px; flex: none; padding: 14px 12px 8px 16px; }
.panel-head-text { flex: 1 1 auto; min-width: 0; }
.panel-eb { margin: 0 0 2px; font: 500 var(--text-sm)/1.2 var(--font-body); color: var(--text-secondary); }
.r-head-title { margin: 0; font: 500 17px/20px var(--font-body); letter-spacing: -.005em; color: var(--text-primary); }
.panel-hbtn { border-radius: 12px; }
.panel-hbtn svg.i { width: 16px; height: 16px; }
.panel-view { flex: 1 1 auto; min-height: 0; overflow-y: auto; padding: 4px 12px 12px 16px; }
/* the empty Topic view: an info card, tinted, with no hover */
.info-card { display: grid; grid-template-columns: 18px minmax(0, 1fr); gap: 10px; padding: 12px 14px; border-radius: var(--r); background: color-mix(in srgb, var(--accent) 7%, transparent); }
.info-card > svg.i { margin-top: 1px; color: var(--accent); }
.info-card-title { margin: 0; font: 500 var(--text-md)/1.4 var(--font-body); color: var(--text-primary); }
.info-card-text { margin: 2px 0 0; font: 400 var(--text-sm)/1.45 var(--font-body); color: var(--text-secondary); }
@media (min-width: 640px) { .app:not(.panel-open) .panel { visibility: hidden; } }
/* the backdrop of the drawer and of the sheet */
.backdrop { position: fixed; inset: 0; z-index: 40; background: var(--scrim); }

/* Collapse menu (computer): the left bar at 64, icons only; the wordmark gives way to the symbol */
@media (min-width: 640px) {
  .app.lb-collapsed { --lb-w: 64px; }
  .app.lb-collapsed .leftbar { padding: 0 12px 12px; }
  .app.lb-collapsed .lb-head { flex-direction: column; justify-content: flex-start; gap: 4px; height: auto; padding-top: 8px; }
  .app.lb-collapsed .lb-brand { padding: 0 2px; }
  .app.lb-collapsed .leftbar .lb-wm, .app.lb-collapsed .lb-label, .app.lb-collapsed .lb-sec, .app.lb-collapsed .lb-fb-text, .app.lb-collapsed .lb-fb-go,
  .app.lb-collapsed .account-trigger-name, .app.lb-collapsed .account-chevron { display: none; }
  .app.lb-collapsed .lb-brand .lb-sym.lb-light { display: block; }
  .app.lb-collapsed .lb-item, .app.lb-collapsed .account-trigger { justify-content: center; padding: 0; }
  .app.lb-collapsed .lb-feedback { justify-content: center; }
  .app.lb-collapsed .lb-acct { flex-direction: column; }
  .app.lb-collapsed .lb-acct > .account-menu, .app.lb-collapsed .lb-admin { width: 40px; }
  :root[data-theme="dark"] .app.lb-collapsed .lb-brand .lb-sym.lb-light { display: none; }
  :root[data-theme="dark"] .app.lb-collapsed .lb-brand .lb-sym.lb-dark { display: block; }
}
@media (min-width: 640px) and (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .app.lb-collapsed .lb-brand .lb-sym.lb-light { display: none; }
  :root:not([data-theme="light"]) .app.lb-collapsed .lb-brand .lb-sym.lb-dark { display: block; }
}
/* Expand panel: 45 % of the window */
.app.panel-wide .panel { width: 45vw; }
@media (min-width: 1280px) { .app.panel-open.panel-wide { --rc-w: calc(45vw + 72px); } }

/* == tooltip == */
/* One layer, #tip, outside .app: a dark chip with an arrow (13/500), beside the button that shows only an icon (the left
   bar collapsed, Admin panel). It only fades in (opacity), and not with prefers-reduced-motion. shell.js places it and
   picks the side: .r (right), .b (under), .t (above); --a is where the arrow points. */
.tip { position: fixed; left: 0; top: 0; z-index: 1000; width: max-content; max-width: 240px; padding: 5px 9px; border-radius: var(--r-sm); background: var(--text-primary);
  font: 500 var(--text-sm)/1.3 var(--font-body); color: var(--bg-primary); white-space: normal; overflow-wrap: break-word; box-shadow: var(--shadow-raised);
  pointer-events: none; opacity: 0; transition: opacity .15s; }
.tip.on { opacity: 1; }
.tip::before { content: ""; position: absolute; width: 8px; height: 8px; border-radius: 1px; background: var(--text-primary); transform: rotate(45deg); }
.tip.r::before { left: -4px; top: calc(var(--a) - 4px); }
.tip.b::before { top: -4px; left: calc(var(--a) - 4px); }
.tip.t::before { bottom: -4px; left: calc(var(--a) - 4px); }
@media (prefers-reduced-motion: reduce) { .tip { transition: none; } }

/* == account menu == */
/* The account in the left bar: the avatar and the name; the menu opens above it, a solid raised surface. */
.account-menu { position: relative; display: flex; align-items: center; }
.account-trigger { display: flex; align-items: center; gap: 8px; width: 100%; min-width: 0; height: 48px; margin: 0; padding: 0 8px; border: 0; border-radius: 10px; background: none;
  font: 500 var(--text-base)/1.2 var(--font-body); color: var(--text-primary); text-align: left; transition: background-color .12s; }
.account-trigger:hover, .account-menu.open .account-trigger { background: var(--bg-muted); }
.account-trigger:focus-visible { outline-offset: 0; }
.account-avatar { display: inline-grid; place-items: center; flex: none; width: 28px; height: 28px; border-radius: 50%; background: var(--bg-primary);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent) 35%, transparent); font: 500 var(--text-sm)/1 var(--font-body); color: var(--link); }
.account-trigger-name { flex: 1 1 auto; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.account-chevron { width: 16px; height: 16px; color: var(--text-secondary); transition: transform .12s; }
.account-menu.open .account-chevron { transform: rotate(180deg); }
.account-popover { position: absolute; left: 0; bottom: calc(100% + 6px); z-index: 80; width: min(264px, calc(100vw - 24px)); padding: 12px; border-radius: var(--r);
  background: linear-gradient(var(--surface-raised), var(--surface-raised)), var(--bg-primary); box-shadow: var(--shadow-soft-lg), inset 0 0 0 1px var(--surface-raised-edge);
  opacity: 0; visibility: hidden; pointer-events: none; transform: translateY(4px); transition: opacity .12s ease-in, transform .12s ease-in, visibility .12s; }
.account-popover-immediate { transition: none; }
.account-menu.open .account-popover { opacity: 1; visibility: visible; pointer-events: auto; transform: none; transition-timing-function: ease-out; transition-duration: .15s; }
.account-popover-head { display: flex; flex-direction: column; gap: 2px; min-width: 0; padding: 0 4px 8px; }
.account-popover-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font: 500 var(--text-md)/1.3 var(--font-body); color: var(--text-primary); }
.account-email { overflow-wrap: anywhere; font: 400 var(--text-sm)/1.4 var(--font-body); color: var(--text-secondary); }
.account-popover-actions { padding: 4px 0 0; border-top: 1px solid var(--hairline); }
.account-logout { display: flex; align-items: center; gap: 8px; width: 100%; height: 36px; margin: 0; padding: 0 8px; border: 0; border-radius: var(--r-sm); background: none;
  font: 400 var(--text-md)/1.2 var(--font-body); color: var(--text-body); text-align: left; transition: background-color .12s; }
.account-logout:hover { background: var(--bg-muted); color: var(--text-primary); }
.account-logout:focus-visible { outline-offset: 0; }
.account-logout:disabled { cursor: wait; opacity: .7; }
.account-logout svg.i { width: 16px; height: 16px; }
.account-logout-status { padding: 4px 8px 0; font: 400 var(--text-sm)/1.35 var(--font-body); color: var(--err-text); }
.account-menu [hidden], .account-menu[hidden] { display: none; }
@media (prefers-reduced-motion: reduce) { .account-trigger, .account-chevron, .account-popover, .account-logout { transition: none; } }

/* == conversation == */
/* The Guided Study screen: the conversation (the student's bubbles, the Tutor's replies in Markdown, the waits and
   the notices), the writing bar with the send button (Stop while a reply arrives) and the AI notice, plus the welcome
   when no Guided Study is open. The conversation and the bar keep generous side margins whatever the column. */
.chat { position: relative; z-index: 1; display: flex; flex-direction: column; gap: 24px; flex: 1 1 auto; min-height: 0; overflow-y: auto;
  padding: 72px clamp(16px, 6%, 72px) 40px; }
.msg { width: 100%; max-width: 720px; margin: 0 auto; animation: msg-in .4s cubic-bezier(.22, 1, .36, 1) both; }
@keyframes msg-in { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
.msg-s { width: fit-content; max-width: 100%; margin-left: auto; padding: 12px 16px; border-radius: var(--r-lg); border-top-right-radius: var(--r-sm);
  background: var(--bg-muted); color: var(--text-primary); white-space: pre-wrap; }
.msg-t { padding: 4px 0; color: var(--text-body); line-height: 1.65; }
.msg-t > :first-child { margin-top: 0; }
.msg-t > :last-child { margin-bottom: 0; }
.msg-t p { margin: 0 0 12px; }
.msg-t strong { font-weight: 500; color: var(--text-primary); }
.msg-t em { font-style: italic; }
.msg-t del { color: var(--text-secondary); }
.msg-t a { color: var(--link); text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 2px; transition: color .1s; }
.msg-t a:hover { color: var(--link-hover); }
.msg-t h1, .msg-t h2, .msg-t h3 { margin: 20px 0 8px; font-family: var(--font-serif); font-weight: 500; line-height: 1.3; color: var(--text-primary); }
.msg-t h1 { font-size: 20px; }
.msg-t h2 { font-size: 18px; }
.msg-t h3 { font-size: 16px; }
.msg-t ul, .msg-t ol { margin: 0 0 12px; padding-left: 22px; }
.msg-t li { margin-bottom: 5px; }
.msg-t li::marker { color: var(--text-secondary); }
.msg-t li > ul, .msg-t li > ol { margin: 5px 0 4px; }
.msg-t blockquote { margin: 0 0 12px; padding: 2px 0 2px 14px; border-left: 2px solid var(--accent-soft); font-family: var(--font-serif); font-style: italic; color: var(--text-secondary); }
.msg-t code { padding: 1.5px 5px; border-radius: 4px; background: var(--bg-muted); font-family: var(--font-mono); font-size: .85em; }
.msg-t pre { overflow-x: auto; margin: 0 0 12px; padding: 12px 16px; border-radius: 6px; background: var(--bg-muted); box-shadow: inset 0 0 0 1px var(--hairline); line-height: 1.55; }
.msg-t pre code { padding: 0; background: none; font-size: 13px; }
.msg-t hr { margin: 16px 0; border: 0; border-top: 1px solid var(--hairline); }
/* the typing cursor while the reply arrives */
.msg-t .caret { display: inline-block; width: 6px; height: 1.05em; margin-left: 2px; vertical-align: -2px; border-radius: 1px; background: var(--accent); opacity: .65; animation: caret-blink 1s steps(1) infinite; }
@keyframes caret-blink { 50% { opacity: 0; } }
.msg-err { margin: 8px 0 0; font-size: var(--text-sm); color: var(--err-text); }
.msg-note { margin-top: 6px; font-size: var(--text-xs); color: var(--text-secondary); }
/* the citation chip [n]: the same in the conversation and in the Bibliography's rows */
.cite { display: inline-flex; align-items: center; justify-content: center; min-width: 18px; height: 18px; margin: 0 1px; padding: 0 4px; border-radius: 6px;
  background: var(--accent-soft); color: var(--link); font: 600 var(--text-xs)/1 var(--font-body); font-variant-numeric: tabular-nums; vertical-align: super;
  text-decoration: none; cursor: pointer; transition: background-color .1s, color .1s; }
.cite:hover, .cite.hl { background: var(--link); color: var(--on-accent); }
/* a closed (copyright-protected) source: the same chip, muted, not a link */
.cite.locked, .cite.locked:hover, .cite.locked.hl { background: var(--bg-muted); color: var(--text-secondary); cursor: default; }
/* the waits and the notices of the conversation (notices.js) */
.loading, .app-notice { display: flex; align-items: center; gap: 5px; flex-shrink: 0; width: 100%; max-width: 700px; margin: 0 auto; padding: 6px 16px; font-size: var(--text-sm); color: var(--text-secondary); }
.app-notice.problem { color: var(--err-text); }
.dot { width: 3px; height: 3px; border-radius: 50%; background: var(--accent); opacity: .4; animation: dot-pulse 1.4s ease-in-out infinite; }
.dot:nth-child(2) { animation-delay: .2s; }
.dot:nth-child(3) { animation-delay: .4s; }
@keyframes dot-pulse { 0%, 100% { opacity: .15; } 50% { opacity: .8; } }
/* the writing bar: a glass field with a faint ring and a point of light circling it, the send button inside */
.input-area { position: relative; z-index: 2; flex-shrink: 0; padding: 10px clamp(16px, 6%, 72px) 0; }
@property --spin { syntax: '<angle>'; initial-value: 0deg; inherits: false; }
.input-wrap { position: relative; max-width: 720px; margin: 0 auto; border-radius: var(--r-lg); }
.input-wrap::before { content: ""; position: absolute; inset: -1.5px; padding: 1.5px; border-radius: calc(var(--r-lg) + 1.5px); pointer-events: none; opacity: .4; transition: opacity .2s;
  background: linear-gradient(135deg, color-mix(in srgb, var(--accent) 35%, transparent), color-mix(in srgb, var(--link) 20%, transparent) 50%, color-mix(in srgb, var(--accent) 35%, transparent));
  -webkit-mask: linear-gradient(var(--mask) 0 0) content-box, linear-gradient(var(--mask) 0 0); -webkit-mask-composite: xor; mask-composite: exclude; }
.input-wrap:focus-within::before { opacity: .6; }
.input-wrap::after { content: ""; position: absolute; inset: -1.5px; padding: 1.5px; border-radius: calc(var(--r-lg) + 1.5px); pointer-events: none; opacity: .8; animation: spin-border 15s linear infinite;
  background: conic-gradient(from var(--spin), color-mix(in srgb, var(--accent) 16%, transparent) 0deg, color-mix(in srgb, var(--accent) 30%, transparent) 120deg,
    color-mix(in srgb, var(--accent) 46%, transparent) 210deg, color-mix(in srgb, var(--accent) 66%, transparent) 285deg, color-mix(in srgb, var(--accent) 85%, transparent) 320deg,
    var(--accent) 338deg, color-mix(in srgb, var(--accent) 55%, transparent) 350deg, color-mix(in srgb, var(--accent) 18%, transparent) 360deg);
  -webkit-mask: linear-gradient(var(--mask) 0 0) content-box, linear-gradient(var(--mask) 0 0); -webkit-mask-composite: xor; mask-composite: exclude; }
.input-wrap:focus-within::after { opacity: 1; animation-duration: 10s; }
@keyframes spin-border { to { --spin: 360deg; } }
.input { position: relative; display: block; width: 100%; max-height: 168px; overflow-y: auto; resize: none; padding: 15px 54px 15px 16px; border: 0; border-radius: var(--r-lg); outline: none;
  background: color-mix(in srgb, var(--bg-primary) 82%, transparent); -webkit-backdrop-filter: blur(12px) saturate(1.3); backdrop-filter: blur(12px) saturate(1.3);
  font: 400 var(--text-base)/1.5 var(--font-body); color: var(--text-primary);
  box-shadow: var(--shadow-raised), 0 8px 30px color-mix(in srgb, var(--accent) 22%, transparent), 0 2px 10px color-mix(in srgb, var(--accent) 12%, transparent); transition: box-shadow .18s; }
.input::placeholder { color: var(--text-secondary); }
.input-wrap:focus-within .input { box-shadow: var(--shadow-raised), 0 12px 44px color-mix(in srgb, var(--accent) 34%, transparent), 0 2px 12px color-mix(in srgb, var(--accent) 16%, transparent); }
.input:disabled { opacity: .7; cursor: not-allowed; }
.btn-send { position: absolute; right: 8px; bottom: 8px; z-index: 2; display: flex; align-items: center; justify-content: center; width: 34px; height: 34px; padding: 0; border: 0; border-radius: 9px;
  background: var(--link); color: var(--on-accent); box-shadow: inset 0 1px 0 var(--ctl-sheen), var(--shadow-raised); transition: transform .14s, background-color .14s; }
.btn-send svg.i { width: 15px; height: 15px; stroke-width: 2; }
.input-wrap.multiline .btn-send { top: auto; bottom: 8px; margin: 0; }
.btn-send:hover { transform: translateY(-1px); background: var(--link-hover); }
.btn-send:active { transform: none; }
.btn-send:disabled { background: var(--text-faint); cursor: not-allowed; transform: none; }
/* Stop, while the reply arrives: discreet, a square */
.btn-send.stop { background: var(--text-secondary); }
.btn-send.stop:hover { background: var(--text-body); transform: none; }
.btn-send.stop svg { display: none; }
.btn-send.stop::after { content: ""; width: 9px; height: 9px; border-radius: 2px; background: var(--bg-primary); }
/* AI notice: the one line every tool with generated content shows while a Guided Study is on the screen, open or ended,
   right under the writing bar, or under the conversation when there is no bar (docs/ARCHITECTURE.md). 12 px, a
   legal-note exception to the 13 px floor (docs/UI.md). Hidden on the welcome, the only screen with no Guided Study
   (course.js mounts .welcome in #chat); no JS of its own. */
.ai-notice { position: relative; z-index: 2; flex-shrink: 0; margin: 0; padding: 8px clamp(16px, 6%, 72px) 20px; font-size: 12px; line-height: 1.4; color: var(--text-secondary); text-align: center; }
.screen:has(.welcome) .ai-notice { display: none; }
/* the welcome */
.welcome { display: flex; align-items: center; justify-content: center; flex: 1; }
.welcome-inner { max-width: 600px; text-align: center; }
.welcome-title { margin-bottom: 10px; font: 400 26px/1.25 var(--font-serif); letter-spacing: -.01em; color: var(--text-primary); text-wrap: balance; }
.welcome-sub { margin-bottom: 28px; font-size: var(--text-sm); line-height: 1.6; color: var(--text-secondary); }
.welcome-note { margin-top: 16px; font-size: var(--text-xs); line-height: 1.5; color: var(--text-secondary); }
@media (prefers-reduced-motion: reduce) { .input-wrap::after, .msg, .msg-t .caret, .dot { animation: none; } }

/* == curriculum roadmap == */
/* The course syllabus (roadmap.js): a section heading per depth-1 node, then every level as one block, a line with a
   marker on each topic, one indent step in per level. A row with no subtopics is a button that opens a Guided Study. */
.rm-list { padding: 0 0 16px; }
.rm-sec { display: flex; gap: 8px; align-items: baseline; padding: 16px 8px 5px; }
.rm-sec:first-child { padding-top: 6px; }
.rm-sec-num { flex-shrink: 0; font-size: var(--text-sm); font-weight: 500; letter-spacing: .02em; color: var(--accent); }
.rm-sec-title { font-size: var(--text-sm); font-weight: 500; line-height: 1.35; letter-spacing: .04em; text-transform: uppercase; color: var(--text-secondary); }
/* THE MARKER IS THE MASTERY SLOT. --rm-mastery (0 to 1) fills the disc clockwise, so how well a student knows a topic is
   read off the same mark at every level. It is declared on the row, so a per-row value (style="--rm-mastery:.6")
   reaches the marker by inheritance. It stays 0 until that data exists: the plain empty ring. */
.rm-item { --rm-mastery: 0; display: flex; gap: 10px; padding: 9px 8px; border-radius: var(--r-sm); }
.rm-leaf { cursor: pointer; }
.rm-leaf:hover { background: var(--bg-muted); }
.rm-leaf:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }
/* positioned so it paints over the level's line, which runs behind it; the colour and the fill set apart, so a value
   the fill cannot use leaves the plain disc */
.rm-dot { position: relative; z-index: 1; display: flex; align-items: center; justify-content: center; flex-shrink: 0; width: 18px; height: 18px; margin-top: 2px; border-radius: 50%;
  border: 2px solid var(--border-strong); color: var(--text-faint); background-color: var(--bg-primary);
  background-image: conic-gradient(var(--accent) calc(clamp(0, var(--rm-mastery), 1) * 360deg), var(--bg-primary) 0); }
.rm-body { display: flex; flex-direction: column; gap: 1px; min-width: 0; }
.rm-num { font-size: var(--text-xs); font-weight: 500; line-height: 1.3; letter-spacing: .02em; color: var(--text-secondary); }
.rm-topic { font-size: var(--text-md); line-height: 1.35; color: var(--text-body); word-break: break-word; }
/* one level: its rows, one indent step in; the line runs the whole block through the centre of the markers and fades
   at both ends over the height of one marker */
.rm-kids { --rm-indent: 20px; position: relative; padding-left: var(--rm-indent); }
.rm-kids::before { content: ""; position: absolute; left: calc(var(--rm-indent) + 16px); top: 0; bottom: 0; width: 2px;
  background: linear-gradient(to bottom, transparent 0, var(--border-strong) 20px, var(--border-strong) calc(100% - 20px), transparent 100%); }

/* == bibliography == */
/* The Bibliography view of the panel (bibliography.js): a card per document, a row per excerpt the Tutor cited, with
   the same [n] as the conversation, the page and the snippet. */
.r-list { display: flex; flex-direction: column; gap: 8px; }
.doc { overflow: hidden; border-radius: var(--r); background: var(--bg-primary); box-shadow: inset 0 0 0 1px var(--hairline), var(--shadow-raised); transition: box-shadow .16s; }
.doc:hover { box-shadow: inset 0 0 0 1px var(--border-strong), var(--shadow-raised); }
.doc-head { display: flex; align-items: flex-start; gap: 7px; padding: 10px 10px 8px; }
.doc-ico { flex-shrink: 0; margin-top: 2px; color: var(--text-secondary); }
.doc-main { min-width: 0; }
.doc-title.o { display: block; font-size: var(--text-sm); font-weight: 500; line-height: 1.35; color: var(--link); text-decoration: none; cursor: pointer; }
.doc-title.o:hover { text-decoration: underline; }
.doc-title.locked { display: flex; align-items: center; gap: 4px; font-size: var(--text-sm); font-weight: 500; line-height: 1.35; color: var(--text-secondary); cursor: default; }
.doc-title.locked svg { flex-shrink: 0; opacity: .7; }
.doc-sub { margin-top: 1px; font-size: var(--text-xs); line-height: 1.4; color: var(--text-secondary); word-break: break-word; }
/* the excerpt row: the whole row is the target (it opens the PDF at its page); cited in the latest reply: a bar on the left */
.exc { position: relative; display: flex; align-items: flex-start; gap: 7px; padding: 8px 10px; border-top: 1px solid var(--hairline); text-decoration: none; transition: background-color .1s; }
a.exc:hover, .exc.hl { background: var(--accent-soft); }
.exc-n { flex-shrink: 0; margin-top: 2px; padding: 1px 4px; border-radius: 4px; background: var(--accent-soft); font-size: var(--text-xs); font-weight: 500; color: var(--link); }
.exc-main { min-width: 0; }
.exc-page { font-size: var(--text-xs); font-weight: 500; line-height: 1.4; color: var(--link); }
.exc.closed .exc-page { color: var(--text-secondary); }
.exc-snippet { display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; margin-top: 2px;
  font-family: var(--font-serif); font-style: italic; font-size: var(--text-xs); line-height: 1.5; color: var(--text-secondary); }
.exc.new::before { content: ""; position: absolute; left: 0; top: 6px; bottom: 6px; width: 2px; border-radius: 2px; background: var(--accent); }

/* == debug chat == */
/* The block an admin with the Debug chat on sees under a Tutor reply (public/debug-render.js emits it, as in /admin):
   small, muted, collapsed; three ranks of heading, a fact list with hint marks, the prompts table. */
.msg-debug { margin-top: 8px; padding: 4px 8px; border-left: 2px solid var(--hairline); border-radius: 4px; background: color-mix(in srgb, var(--text-secondary) 5%, transparent);
  font-size: var(--text-xs); color: var(--text-secondary); }
.msg-debug > summary { display: inline-flex; align-items: center; gap: 5px; list-style: none; cursor: pointer; color: var(--text-secondary); }
.msg-debug > summary::-webkit-details-marker, .msg-debug .dbg-sys > summary::-webkit-details-marker { display: none; }
/* the disclosure triangle, right of the label, turning when open */
.msg-debug > summary::after, .msg-debug .dbg-sys > summary::after { content: ""; flex-shrink: 0; width: 0; height: 0;
  border-left: 5px solid var(--text-secondary); border-top: 4px solid transparent; border-bottom: 4px solid transparent; transition: transform .12s, border-left-color .12s; }
.msg-debug[open] > summary::after, .msg-debug .dbg-sys[open] > summary::after { transform: rotate(90deg); }
.msg-debug > summary:hover::after, .msg-debug .dbg-sys > summary:hover::after { border-left-color: var(--accent); }
.msg-debug .dbg-deeplink { margin: 4px 0 2px; }
.msg-debug .dbg-deeplink a { color: var(--text-secondary); text-decoration: underline; }
.msg-debug .dbg-sec { margin: 12px 0 0; padding-top: 10px; border-top: 1px solid var(--hairline); }
.msg-debug .dbg-sec:first-of-type { margin-top: 8px; padding-top: 0; border-top: 0; }
.msg-debug .dbg-sh { margin: 0 0 8px; padding-bottom: 4px; border-bottom: 1px solid var(--hairline); font-size: 10px; font-weight: 500; letter-spacing: .08em; text-transform: uppercase; color: var(--text-body); }
.msg-debug .dbg-sub { margin: 10px 0 10px 10px; padding-left: 10px; border-left: 2px solid var(--border-strong); }
.msg-debug .dbg-subh { margin: 0 0 6px; font-size: 10px; font-weight: 500; letter-spacing: .05em; text-transform: uppercase; color: var(--text-secondary); }
.msg-debug .dbg-plabel { margin: 8px 0 3px; font-size: var(--text-xs); font-weight: 500; color: var(--text-secondary); }
.msg-debug .dbg-facts { display: grid; grid-template-columns: max-content 1fr; gap: 6px 16px; margin: 6px 0; line-height: 1.5; }
.msg-debug .dbg-fk { white-space: nowrap; color: var(--text-faint); }
/* a fact label with data-hint: a small circled "i" marks it, and a dark box shows the hint on hover or focus */
.msg-debug .dbg-fk[data-hint] { position: relative; cursor: help; }
.msg-debug .dbg-fk[data-hint]::after { content: "i"; display: inline-flex; align-items: center; justify-content: center; width: 9px; height: 9px; margin-left: 5px; border: 1px solid var(--border-strong);
  border-radius: 50%; font-size: 7px; font-weight: 500; font-style: italic; line-height: 1; vertical-align: baseline; color: var(--text-secondary); transform: translateY(-1px); transition: color .12s, border-color .12s; }
.msg-debug .dbg-fk[data-hint]:hover::after { color: var(--accent); border-color: var(--accent); }
.msg-debug .dbg-fk[data-hint]:hover::before, .msg-debug .dbg-fk[data-hint]:focus::before { content: attr(data-hint); position: absolute; left: 0; top: calc(100% + 4px); z-index: 40;
  width: max-content; max-width: 280px; padding: 6px 9px; border-radius: 6px; background: var(--text-primary); color: var(--bg-primary); box-shadow: var(--shadow-soft-lg);
  font-size: var(--text-xs); font-weight: 400; line-height: 1.4; letter-spacing: 0; text-transform: none; white-space: normal; pointer-events: none; }
.msg-debug .dbg-fv { color: var(--text-secondary); word-break: break-word; }
.msg-debug .dbg-items { margin: 5px 0 5px 16px; padding: 0; line-height: 1.5; color: var(--text-secondary); }
.msg-debug .dbg-err { margin: 6px 0; font-size: var(--text-xs); line-height: 1.5; color: var(--err-text); }
.msg-debug .dbg-caption { margin: 3px 0 6px; font-style: italic; line-height: 1.5; color: var(--text-faint); }
/* a configuration override: an amber banner, never folded into the reasoning */
.msg-debug .dbg-banner-warn { margin: 2px 0 4px; padding: 3px 7px; border-radius: 4px; background: color-mix(in srgb, var(--warning) 14%, transparent); color: var(--warning); }
.msg-debug .dbg-prompts { width: 100%; margin: 4px 0; border-collapse: collapse; }
.msg-debug .dbg-prompts th, .msg-debug .dbg-prompts td { padding: 4px 8px 4px 0; border-bottom: 1px solid var(--hairline); text-align: left; vertical-align: top; }
.msg-debug .dbg-prompts th { font-weight: 500; color: var(--text-faint); }
.msg-debug .dbg-prompts tr.row-custom td { color: var(--warning); }
.msg-debug .dbg-hash { font-family: var(--font-mono); color: var(--text-faint); }
/* a collapsible summary is a control, not a heading: sentence case, normal weight, the triangle */
.msg-debug .dbg-sys { margin: 6px 0; }
.msg-debug .dbg-sys > summary { display: inline-flex; align-items: center; gap: 5px; margin: 6px 0 3px; list-style: none; cursor: pointer; font-weight: 500; color: var(--text-secondary); }
.msg-debug .dbg-sys > summary:hover, .msg-debug .dbg-sys[open] > summary { color: var(--text-body); }
.msg-debug .dbg-sys[open] > *:not(summary) { margin-left: 12px; }
.msg-debug .dbg-sys pre { max-height: 40vh; overflow: auto; margin: 4px 0 0; padding: 10px; border-radius: 6px; background: color-mix(in srgb, var(--text-secondary) 6%, transparent);
  box-shadow: inset 0 0 0 1px var(--hairline); font-family: var(--font-mono); font-size: var(--text-xs); white-space: pre-wrap; word-break: break-word; }

/* == phone == */
/* Below 640: one column. The island #topbar runs edge to edge at 8 (Menu, the symbol, the path, Open panel; 44 px
   targets); the left bar is the drawer, over a dimmed background; the panel is a sheet from the bottom, half the
   window, with its views as tabs on top; the icon bar goes. */
@media (max-width: 639px) {
  .app { grid-template-columns: minmax(0, 1fr); }
  .main { grid-column: 1; }
  .leftbar { position: fixed; top: 0; bottom: 0; left: 0; z-index: 50; width: 280px; background: var(--bg-subtle); -webkit-backdrop-filter: none; backdrop-filter: none;
    box-shadow: var(--shadow-soft-lg); transform: translateX(-105%); visibility: hidden; transition: transform .2s ease, visibility 0s .2s; }
  .app.drawer-open .leftbar { transform: none; visibility: visible; transition: transform .2s ease; }
  .lb-collapse { display: none; }
  .lb-close { display: inline-grid; width: 44px; height: 44px; border-radius: 10px; }
  .lb-brand { height: 44px; }
  .topbar { left: 8px; right: 8px; max-width: none; min-height: 0; gap: 0; padding: 2px; }
  .isl-btn { display: grid; }
  .path { padding: 0 4px; }
  .course-name { overflow: hidden; text-overflow: ellipsis; }
  .path { position: static; }
  .course-btn { height: 44px; }
  .course-menu { left: 0; right: 0; width: auto; }
  .course-opt { min-height: 44px; }
  .course-ck { display: block; }
  .offline-banner { top: 64px; left: 8px; right: 8px; }
  .page { padding-top: 72px; }
  .chat { padding: 72px 12px 16px; }
  .input-area { padding-left: 12px; padding-right: 12px; }
  .input { font-size: var(--text-input); }
  .ai-notice { padding: 8px 12px calc(20px + env(safe-area-inset-bottom)); }
  .panel-bar { display: none; }
  .panel { position: fixed; top: auto; left: 0; right: 0; bottom: 0; z-index: 50; width: auto; height: 50vh; height: 50dvh; border-radius: var(--r-lg) var(--r-lg) 0 0;
    background: var(--bg-primary); -webkit-backdrop-filter: none; backdrop-filter: none; box-shadow: var(--shadow-sheet), inset 0 1px 0 var(--hairline);
    transform: translateY(105%); visibility: hidden; transition: transform .2s ease, visibility 0s .2s; }
  .app.sheet-open .panel { transform: none; visibility: visible; transition: transform .2s ease; }
  .panel-tabs { display: flex; gap: 4px; flex: none; padding: 4px 8px 0; }
  .panel-tab { display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 2px; min-width: 64px; height: 48px; margin: 0; padding: 0 8px; border: 0;
    border-radius: 12px; background: none; font: 500 12px/1.2 var(--font-body); color: var(--text-secondary); }
  .panel-tab[aria-selected="true"] { color: var(--link); }
  .panel-tab svg.i { width: 20px; height: 20px; }
  #panel-expand { display: none; }
  .panel-hbtn { width: 44px; height: 44px; }
}
@media (prefers-reduced-motion: reduce) { .leftbar, .panel { transition: none; } }
/* hidden wins over every display above */
.app [hidden] { display: none; }