/* ML Mastery — design system
   Direction: a technical monograph. Paper ground, ink text, one viridian accent, hairline rules.
   Type: Instrument Serif (display) · IBM Plex Sans (body/UI) · IBM Plex Mono (code, numerals). */

:root {
  --bg: #F4F5F2;
  --bg-2: #ECEEEA;
  --bg-3: #E3E6E1;
  --ink: #15181A;
  --ink-2: #5C6670;
  --ink-3: #8B949B;
  --rule: #D6DAD5;
  --rule-2: #C4CAC4;
  --accent: #1E6B5A;
  --accent-ink: #F4F5F2;
  --accent-soft: #DCEBE5;
  --accent-line: #8FBDAE;
  --warn: #8F5A00;
  --warn-soft: #F2E7CE;
  --bad: #9B2E2E;
  --bad-soft: #F1D9D9;
  --code-bg: #EAECE7;
  --sel: rgba(30,107,90,.18);

  --font-display: "Instrument Serif", "Iowan Old Style", "Palatino Linotype", Georgia, serif;
  --font-body: "IBM Plex Sans", "Helvetica Neue", Arial, system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  --measure: 68ch;
  --rail-w: 292px;
  --toc-w: 220px;
  --radius: 3px;
  --fs: 17px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #121615; --bg-2: #181D1B; --bg-3: #1F2624;
    --ink: #E6E8E3; --ink-2: #A0A9A3; --ink-3: #737C77;
    --rule: #283030; --rule-2: #364040;
    --accent: #63C2A5; --accent-ink: #0F1513; --accent-soft: #1B2E28; --accent-line: #2F6B5A;
    --warn: #D9A441; --warn-soft: #2C2515;
    --bad: #E07A7A; --bad-soft: #3A1F1F;
    --code-bg: #1A201E; --sel: rgba(99,194,165,.25);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #121615; --bg-2: #181D1B; --bg-3: #1F2624;
  --ink: #E6E8E3; --ink-2: #A0A9A3; --ink-3: #737C77;
  --rule: #283030; --rule-2: #364040;
  --accent: #63C2A5; --accent-ink: #0F1513; --accent-soft: #1B2E28; --accent-line: #2F6B5A;
  --warn: #D9A441; --warn-soft: #2C2515;
  --bad: #E07A7A; --bad-soft: #3A1F1F;
  --code-bg: #1A201E; --sel: rgba(99,194,165,.25);
  color-scheme: dark;
}
:root[data-fs="s"] { --fs: 15.5px; }
:root[data-fs="l"] { --fs: 19px; }

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } *, *::before, *::after { transition: none !important; animation: none !important; } }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: var(--font-body); font-size: var(--fs); line-height: 1.6;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}
::selection { background: var(--sel); }
a { color: var(--accent); text-decoration: none; text-underline-offset: .18em; }
a:hover { text-decoration: underline; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
kbd { font-family: var(--font-mono); font-size: .72em; padding: .1em .4em; border: 1px solid var(--rule-2); border-bottom-width: 2px; border-radius: var(--radius); color: var(--ink-2); background: var(--bg); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
hr { border: 0; border-top: 1px solid var(--rule); margin: 2rem 0; }
[hidden] { display: none !important; }

/* ---------- App frame ---------- */
.app { display: grid; grid-template-columns: var(--rail-w) minmax(0, 1fr); min-height: 100vh; }
.rail {
  position: sticky; top: 0; height: 100vh; overflow: hidden; display: flex; flex-direction: column;
  background: var(--bg-2); border-right: 1px solid var(--rule);
}
.rail-head { display: flex; align-items: center; justify-content: space-between; padding: 18px 18px 10px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); }
.brand:hover { text-decoration: none; }
.brand-mark { color: var(--accent); flex: none; }
.brand-name { font-family: var(--font-display); font-size: 1.45rem; letter-spacing: .01em; line-height: 1; }
.rail .rail-close { display: none; }
.search-trigger {
  display: flex; align-items: center; gap: 10px; margin: 4px 14px 12px; padding: 8px 10px;
  border: 1px solid var(--rule-2); border-radius: var(--radius); color: var(--ink-2); background: var(--bg); font-size: .9rem; text-align: left;
}
.search-trigger span { flex: 1; }
.search-trigger:hover { border-color: var(--accent-line); color: var(--ink); }
.rail-nav { flex: 1; overflow-y: auto; padding: 0 8px 12px; scrollbar-width: thin; }
.rail-foot { display: flex; flex-wrap: wrap; gap: 2px 14px; padding: 12px 18px 16px; border-top: 1px solid var(--rule); font-size: .84rem; }
.rail-foot a { color: var(--ink-2); }
.rail-foot a:hover, .rail-foot a.active { color: var(--accent); text-decoration: none; }

.nav-mod { margin: 2px 0; }
.nav-mod-head {
  display: grid; grid-template-columns: 30px 1fr auto; align-items: center; gap: 6px; width: 100%;
  padding: 7px 10px; border-radius: var(--radius); text-align: left; color: var(--ink); font-size: .9rem; font-weight: 500;
}
.nav-mod-head:hover { background: var(--bg-3); }
.nav-mod-head .num { font-family: var(--font-mono); font-size: .72rem; color: var(--ink-3); letter-spacing: .04em; }
.nav-mod-head .pct { font-family: var(--font-mono); font-size: .7rem; color: var(--ink-3); font-variant-numeric: tabular-nums; }
.nav-mod-head .pct.done { color: var(--accent); }
.nav-mod.open .nav-mod-head { color: var(--accent); }
.nav-mod-body { display: none; padding: 2px 0 6px 0; }
.nav-mod.open .nav-mod-body { display: block; }
.nav-lesson {
  display: grid; grid-template-columns: 30px 1fr; align-items: start; gap: 6px; padding: 5px 10px 5px 10px; border-radius: var(--radius);
  color: var(--ink-2); font-size: .85rem; line-height: 1.35;
}
.nav-lesson:hover { background: var(--bg-3); color: var(--ink); text-decoration: none; }
.nav-lesson.active { background: var(--accent-soft); color: var(--ink); }
.nav-lesson .dot { width: 14px; height: 14px; margin: 3px 0 0 3px; border: 1.5px solid var(--rule-2); border-radius: 50%; display: inline-block; }
.nav-lesson.done .dot { background: var(--accent); border-color: var(--accent); }
.nav-lesson.started .dot { border-color: var(--accent); background: linear-gradient(to right, var(--accent) 50%, transparent 50%); }
.nav-lesson.active .dot { border-color: var(--accent); }

.rail-scrim { display: none; }
.main { min-width: 0; position: relative; }
.progress-line { position: sticky; top: 0; height: 2px; background: transparent; z-index: 30; }
.progress-line span { display: block; height: 100%; width: 0; background: var(--accent); transition: width .1s linear; }
.topbar {
  position: sticky; top: 2px; z-index: 20; display: flex; align-items: center; gap: 12px; height: 52px; padding: 0 28px;
  background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(8px); border-bottom: 1px solid var(--rule);
}
.topbar .menu-btn { display: none; }
.crumbs { flex: 1; min-width: 0; font-size: .84rem; color: var(--ink-2); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.crumbs a { color: var(--ink-2); }
.crumbs a:hover { color: var(--accent); }
.crumbs .sep { margin: 0 8px; color: var(--ink-3); }
.topbar-right { display: flex; align-items: center; gap: 4px; }
.streak { font-family: var(--font-mono); font-size: .75rem; color: var(--ink-2); margin-right: 8px; font-variant-numeric: tabular-nums; }
.streak b { color: var(--accent); font-weight: 500; }
.icon-btn { display: inline-flex; align-items: center; justify-content: center; width: 34px; height: 34px; border-radius: var(--radius); color: var(--ink-2); }
.icon-btn:hover { background: var(--bg-3); color: var(--ink); }
.ico-moon { display: none; }
:root[data-theme="dark"] .ico-sun { display: none; }
:root[data-theme="dark"] .ico-moon { display: block; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .ico-sun { display: none; }
  :root:not([data-theme="light"]) .ico-moon { display: block; }
}

.view { padding: 0 28px 80px; }
.view:focus { outline: none; }

/* ---------- Common blocks ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 9px 14px; border-radius: var(--radius);
  background: var(--accent); color: var(--accent-ink); font-size: .9rem; font-weight: 500; border: 1px solid transparent; line-height: 1.2;
}
.btn:hover { text-decoration: none; filter: brightness(1.05); }
.btn.ghost { background: transparent; color: var(--ink); border-color: var(--rule-2); }
.btn.ghost:hover { border-color: var(--accent); color: var(--accent); }
.btn.done { background: var(--accent-soft); color: var(--accent); border-color: var(--accent-line); }
.btn.small { padding: 6px 10px; font-size: .8rem; }
.btn.danger { background: transparent; color: var(--bad); border-color: var(--bad); }
.btn svg { flex: none; }
.eyebrow { font-family: var(--font-mono); font-size: .72rem; letter-spacing: .08em; text-transform: uppercase; color: var(--ink-2); }
.eyebrow .num { color: var(--accent); }
.display { font-family: var(--font-display); font-weight: 400; letter-spacing: -.005em; line-height: 1.05; text-wrap: balance; margin: 0; }
.lead { font-size: 1.15rem; color: var(--ink-2); max-width: var(--measure); text-wrap: pretty; }
.meter { height: 4px; background: var(--bg-3); border-radius: 2px; overflow: hidden; }
.meter span { display: block; height: 100%; background: var(--accent); }
.pill { display: inline-block; font-family: var(--font-mono); font-size: .7rem; letter-spacing: .04em; padding: 2px 7px; border: 1px solid var(--rule-2); border-radius: 999px; color: var(--ink-2); }
.pill.accent { border-color: var(--accent-line); color: var(--accent); }
.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
.muted { color: var(--ink-2); }
.grid-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
@media (max-width: 900px) { .grid-2, .grid-3 { grid-template-columns: 1fr; } }
.card { border: 1px solid var(--rule); border-radius: var(--radius); background: var(--bg); padding: 18px 20px; }
.card h3 { margin: 0 0 6px; font-size: 1.05rem; font-weight: 500; }
.card p { margin: 0; color: var(--ink-2); font-size: .92rem; }
.empty { color: var(--ink-2); padding: 40px 0; text-align: center; font-style: italic; }

/* ---------- Home ---------- */
.page { max-width: 1080px; margin: 0 auto; padding-top: 44px; }
.hero { display: grid; grid-template-columns: minmax(0, 1.4fr) minmax(280px, 1fr); gap: 40px; align-items: end; padding-bottom: 36px; border-bottom: 1px solid var(--rule); }
.hero h1 { font-size: clamp(2.6rem, 5vw, 4.2rem); margin: 10px 0 14px; }
.hero h1 em { font-style: italic; color: var(--accent); }
.continue {
  border: 1px solid var(--rule-2); border-radius: var(--radius); padding: 18px 20px; background: var(--bg-2);
}
.continue .eyebrow { margin-bottom: 8px; }
.continue h3 { font-family: var(--font-display); font-weight: 400; font-size: 1.5rem; margin: 0 0 4px; line-height: 1.15; }
.continue .where { color: var(--ink-2); font-size: .88rem; margin-bottom: 14px; }
.continue .meter { margin: 10px 0 14px; }
.stats { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0; margin: 28px 0 40px; border: 1px solid var(--rule); border-radius: var(--radius); }
.stat { padding: 16px 18px; border-right: 1px solid var(--rule); }
.stat:last-child { border-right: 0; }
.stat .v { font-family: var(--font-display); font-size: 2rem; line-height: 1; font-variant-numeric: tabular-nums; }
.stat .k { font-size: .8rem; color: var(--ink-2); margin-top: 6px; }
@media (max-width: 800px) { .stats { grid-template-columns: repeat(2, 1fr); } .stat:nth-child(2) { border-right: 0; } .stat:nth-child(-n+2) { border-bottom: 1px solid var(--rule); } .hero { grid-template-columns: 1fr; } }
.section-head { display: flex; align-items: baseline; justify-content: space-between; gap: 16px; margin: 36px 0 14px; }
.section-head h2 { font-family: var(--font-display); font-weight: 400; font-size: 1.7rem; margin: 0; }
.section-head a { font-size: .86rem; }
.modules { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
@media (max-width: 860px) { .modules { grid-template-columns: 1fr; } }
.module-card { display: grid; grid-template-columns: 44px 1fr; gap: 14px; padding: 18px 20px 16px; border: 1px solid var(--rule); border-radius: var(--radius); color: var(--ink); background: var(--bg); transition: border-color .15s; }
.module-card:hover { border-color: var(--accent-line); text-decoration: none; }
.module-card .num { font-family: var(--font-display); font-size: 1.6rem; color: var(--ink-3); line-height: 1; padding-top: 3px; }
.module-card h3 { margin: 0 0 4px; font-size: 1.08rem; font-weight: 500; }
.module-card p { margin: 0 0 12px; color: var(--ink-2); font-size: .88rem; }
.module-card .foot { display: flex; align-items: center; gap: 10px; font-family: var(--font-mono); font-size: .72rem; color: var(--ink-3); }
.module-card .meter { flex: 1; }
.module-card.complete .num { color: var(--accent); }
.paths { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; }
@media (max-width: 900px) { .paths { grid-template-columns: 1fr; } }
.path { border: 1px solid var(--rule); border-radius: var(--radius); padding: 18px 20px; }
.path h3 { margin: 0 0 4px; font-weight: 500; font-size: 1rem; }
.path p { margin: 0 0 10px; font-size: .88rem; color: var(--ink-2); }
.path .mono { font-size: .72rem; color: var(--ink-3); }

/* ---------- Module page ---------- */
.mod-hero { padding-bottom: 28px; border-bottom: 1px solid var(--rule); margin-bottom: 22px; }
.mod-hero h1 { font-size: clamp(2.2rem, 4vw, 3.4rem); margin: 8px 0 12px; }
.lesson-list { list-style: none; margin: 0; padding: 0; }
.lesson-row { display: grid; grid-template-columns: 26px 54px 1fr auto; gap: 14px; align-items: start; padding: 16px 6px; border-bottom: 1px solid var(--rule); color: var(--ink); }
.lesson-row:hover { text-decoration: none; background: var(--bg-2); }
.lesson-row .dot { width: 14px; height: 14px; margin-top: 6px; border: 1.5px solid var(--rule-2); border-radius: 50%; }
.lesson-row.done .dot { background: var(--accent); border-color: var(--accent); }
.lesson-row.started .dot { border-color: var(--accent); background: linear-gradient(to right, var(--accent) 50%, transparent 50%); }
.lesson-row .idx { font-family: var(--font-mono); font-size: .78rem; color: var(--ink-3); padding-top: 5px; }
.lesson-row h3 { margin: 0 0 3px; font-weight: 500; font-size: 1.04rem; }
.lesson-row p { margin: 0; color: var(--ink-2); font-size: .88rem; }
.lesson-row .min { font-family: var(--font-mono); font-size: .74rem; color: var(--ink-3); padding-top: 6px; white-space: nowrap; }

/* ---------- Lesson ---------- */
.lesson-layout { display: grid; grid-template-columns: minmax(0, 1fr) var(--toc-w); gap: 48px; max-width: calc(var(--measure) + var(--toc-w) + 48px + 4rem); margin: 0 auto; padding-top: 40px; }
.lesson-main { min-width: 0; }
.lesson-head { padding-bottom: 24px; border-bottom: 1px solid var(--rule); margin-bottom: 30px; }
.lesson-head h1 { font-size: clamp(2rem, 3.6vw, 3rem); margin: 8px 0 12px; }
.lesson-meta { display: flex; flex-wrap: wrap; gap: 8px 18px; align-items: center; font-size: .84rem; color: var(--ink-2); font-family: var(--font-mono); }
.lesson-meta .done-flag { color: var(--accent); }
.prose { max-width: var(--measure); font-size: 1rem; line-height: 1.68; }
.prose > * + * { margin-top: 1em; }
.prose h2 { font-family: var(--font-display); font-weight: 400; font-size: 1.85rem; line-height: 1.12; margin-top: 2.2em; margin-bottom: .4em; letter-spacing: -.005em; scroll-margin-top: 80px; }
.prose h3 { font-size: 1.12rem; font-weight: 600; margin-top: 1.8em; margin-bottom: .3em; scroll-margin-top: 80px; }
.prose h4 { font-size: 1rem; font-weight: 600; margin: 0 0 .5em; }
.prose p { text-wrap: pretty; }
.prose ul, .prose ol { padding-left: 1.4em; }
.prose li + li { margin-top: .35em; }
.prose dfn { font-style: normal; font-weight: 600; border-bottom: 1px dotted var(--accent-line); }
.prose strong { font-weight: 600; }
.prose table { border-collapse: collapse; width: 100%; font-size: .9rem; display: block; overflow-x: auto; }
.prose thead th { text-align: left; font-weight: 600; border-bottom: 1.5px solid var(--ink); padding: 8px 10px; }
.prose td { padding: 8px 10px; border-bottom: 1px solid var(--rule); vertical-align: top; }
.prose figure { margin: 1.6em 0; }
.prose figure svg { max-width: 100%; height: auto; display: block; margin: 0 auto; color: var(--ink); }
.prose figcaption { font-size: .84rem; color: var(--ink-2); text-align: center; margin-top: 8px; }
.prose img { max-width: 100%; }
.prose code { font-family: var(--font-mono); font-size: .86em; background: var(--code-bg); padding: .1em .35em; border-radius: var(--radius); }
.prose pre { position: relative; background: var(--code-bg); border: 1px solid var(--rule); border-radius: var(--radius); padding: 14px 16px; overflow-x: auto; font-size: .84rem; line-height: 1.55; margin: 1.4em 0; }
.prose pre code { background: none; padding: 0; font-size: inherit; }
.copy-btn { position: absolute; top: 6px; right: 6px; font-family: var(--font-mono); font-size: .68rem; padding: 3px 8px; border: 1px solid var(--rule-2); border-radius: var(--radius); color: var(--ink-2); background: var(--bg); opacity: 0; transition: opacity .15s; }
.prose pre:hover .copy-btn, .copy-btn:focus-visible { opacity: 1; }
.copy-btn:hover { color: var(--accent); border-color: var(--accent-line); }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 4px 0; margin: 1.2em 0 !important; }
.katex { font-size: 1.04em; }

.callout { border: 1px solid var(--rule); border-radius: var(--radius); padding: 14px 18px 14px; margin: 1.6em 0; background: var(--bg-2); }
.callout > strong { display: block; font-family: var(--font-mono); font-size: .7rem; letter-spacing: .08em; text-transform: uppercase; font-weight: 500; color: var(--ink-2); margin-bottom: 6px; }
.callout > p { margin: 0; }
.callout > p + p, .callout > ul, .callout > ol, .callout > pre { margin-top: .7em; }
.callout.intuition { background: var(--accent-soft); border-color: var(--accent-line); }
.callout.intuition > strong { color: var(--accent); }
.callout.warn { background: var(--warn-soft); border-color: color-mix(in srgb, var(--warn) 40%, transparent); }
.callout.warn > strong { color: var(--warn); }
.callout.try > strong { color: var(--accent); }
.callout.deeper { background: transparent; border-style: dashed; }
.worked { border-top: 2px solid var(--ink); border-bottom: 1px solid var(--rule); padding: 14px 0 16px; margin: 1.8em 0; }
.worked h4 { font-family: var(--font-display); font-weight: 400; font-size: 1.3rem; margin: 0 0 .5em; }

/* Lesson sections after prose */
.lesson-section { max-width: var(--measure); margin-top: 3rem; padding-top: 1.6rem; border-top: 1px solid var(--rule); }
.lesson-section h2 { font-family: var(--font-display); font-weight: 400; font-size: 1.7rem; margin: 0 0 .3em; }
.lesson-section .sub { color: var(--ink-2); font-size: .9rem; margin: 0 0 1.2em; }
.takeaways { list-style: none; padding: 0; margin: 0; counter-reset: tk; }
.takeaways li { position: relative; padding-left: 2.2em; margin-bottom: .7em; }
.takeaways li::before { counter-increment: tk; content: counter(tk, decimal-leading-zero); position: absolute; left: 0; top: .15em; font-family: var(--font-mono); font-size: .74rem; color: var(--accent); }

.videos { display: grid; gap: 14px; }
.video { border: 1px solid var(--rule); border-radius: var(--radius); overflow: hidden; background: var(--bg-2); }
.video-frame { position: relative; aspect-ratio: 16 / 9; background: #0b0d0c; }
.video-frame img { width: 100%; height: 100%; object-fit: cover; display: block; opacity: .92; }
.video-frame iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.video-play { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; width: 100%; height: 100%; }
.video-play span { display: inline-flex; align-items: center; justify-content: center; width: 60px; height: 60px; border-radius: 50%; background: rgba(244,245,242,.92); color: #15181A; transition: transform .15s; }
.video-play:hover span { transform: scale(1.06); }
.video-play svg { margin-left: 3px; }
.video-body { display: grid; grid-template-columns: 1fr auto; gap: 8px 14px; align-items: start; padding: 12px 14px; }
.video-body h3 { margin: 0; font-size: .96rem; font-weight: 500; line-height: 1.3; }
.video-body .ch { color: var(--ink-2); font-size: .8rem; margin-top: 3px; }
.video-body .ext { font-size: .76rem; font-family: var(--font-mono); white-space: nowrap; color: var(--ink-2); padding-top: 3px; }
.video-body .ext:hover { color: var(--accent); }
.video.playlist .video-frame { display: grid; place-items: center; background: var(--bg-3); }
.video.playlist .video-frame svg { color: var(--ink-2); }

.quiz-q { padding: 16px 0; border-bottom: 1px solid var(--rule); }
.quiz-q:last-child { border-bottom: 0; }
.quiz-q .qt { font-weight: 500; margin: 0 0 10px; }
.quiz-q .qt .n { font-family: var(--font-mono); font-size: .74rem; color: var(--accent); margin-right: 10px; }
.quiz-opts { display: grid; gap: 6px; }
.quiz-opt { display: grid; grid-template-columns: 22px 1fr; gap: 10px; align-items: start; text-align: left; padding: 8px 10px; border: 1px solid var(--rule); border-radius: var(--radius); background: var(--bg); font-size: .94rem; line-height: 1.45; }
.quiz-opt:hover { border-color: var(--accent-line); }
.quiz-opt .l { font-family: var(--font-mono); font-size: .74rem; color: var(--ink-3); padding-top: 3px; }
.quiz-opt.correct { border-color: var(--accent); background: var(--accent-soft); }
.quiz-opt.wrong { border-color: var(--bad); background: var(--bad-soft); }
.quiz-opt[disabled] { cursor: default; }
.quiz-explain { margin: 10px 0 0; padding: 10px 12px; font-size: .9rem; border-left: 2px solid var(--accent); background: var(--bg-2); }
.quiz-explain.bad { border-left-color: var(--bad); }
.quiz-score { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 16px; padding: 12px 14px; border: 1px solid var(--rule-2); border-radius: var(--radius); font-size: .92rem; }
.quiz-score b { font-family: var(--font-display); font-size: 1.5rem; font-weight: 400; }

.reading-list, .ex-list { list-style: none; margin: 0; padding: 0; }
.reading-list li { padding: 10px 0; border-bottom: 1px solid var(--rule); }
.reading-list li:last-child { border-bottom: 0; }
.reading-list a { font-weight: 500; }
.reading-list .note { display: block; color: var(--ink-2); font-size: .88rem; margin-top: 2px; }
.reading-list .host { font-family: var(--font-mono); font-size: .7rem; color: var(--ink-3); margin-left: 8px; }
.ex-list { counter-reset: ex; }
.ex-list li { position: relative; padding: 10px 0 10px 2.6em; border-bottom: 1px solid var(--rule); }
.ex-list li:last-child { border-bottom: 0; }
.ex-list li::before { counter-increment: ex; content: "Ex. " counter(ex); position: absolute; left: 0; top: .9em; font-family: var(--font-mono); font-size: .7rem; color: var(--accent); letter-spacing: .04em; }
.ex-list li label { display: grid; grid-template-columns: 18px 1fr; gap: 10px; align-items: start; cursor: pointer; }
.ex-list li input { margin: 5px 0 0; accent-color: var(--accent); }
.ex-list li.checked { color: var(--ink-3); }
.gloss-inline { display: grid; gap: 8px; }
.gloss-inline div { font-size: .92rem; }
.gloss-inline b { font-weight: 600; }

.notes-box { width: 100%; min-height: 160px; padding: 12px 14px; font: inherit; font-size: .95rem; line-height: 1.55; color: var(--ink); background: var(--bg-2); border: 1px solid var(--rule-2); border-radius: var(--radius); resize: vertical; }
.notes-box:focus { border-color: var(--accent); outline: none; }
.notes-hint { font-size: .78rem; color: var(--ink-3); font-family: var(--font-mono); margin-top: 6px; }

.lesson-actions { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-top: 3rem; padding-top: 1.6rem; border-top: 1px solid var(--rule); max-width: var(--measure); }
.lesson-actions .spacer { flex: 1; }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 2rem; max-width: var(--measure); }
.pager a { display: block; padding: 14px 16px; border: 1px solid var(--rule); border-radius: var(--radius); color: var(--ink); }
.pager a:hover { border-color: var(--accent-line); text-decoration: none; }
.pager a.next { text-align: right; }
.pager .lbl { display: block; font-family: var(--font-mono); font-size: .7rem; letter-spacing: .06em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 4px; }
.pager .t { font-weight: 500; font-size: .95rem; }

.toc { position: sticky; top: 74px; align-self: start; max-height: calc(100vh - 100px); overflow-y: auto; font-size: .82rem; scrollbar-width: thin; }
.toc-title { font-family: var(--font-mono); font-size: .68rem; letter-spacing: .08em; text-transform: uppercase; color: var(--ink-3); margin: 0 0 10px; }
.toc ol { list-style: none; margin: 0; padding: 0; border-left: 1px solid var(--rule); }
.toc li a { display: block; padding: 4px 0 4px 12px; color: var(--ink-2); margin-left: -1px; border-left: 1px solid transparent; line-height: 1.35; }
.toc li.h3 a { padding-left: 24px; font-size: .78rem; }
.toc li a:hover { color: var(--ink); text-decoration: none; }
.toc li a.active { color: var(--accent); border-left-color: var(--accent); }
.toc-tools { margin-top: 22px; padding-top: 14px; border-top: 1px solid var(--rule); display: grid; gap: 6px; }
.toc-tools button, .toc-tools a { display: flex; align-items: center; gap: 8px; text-align: left; color: var(--ink-2); padding: 3px 0; font-size: .8rem; }
.toc-tools button:hover, .toc-tools a:hover { color: var(--accent); text-decoration: none; }
.toc-tools kbd { margin-left: auto; }
.toc-time { font-family: var(--font-mono); font-size: .7rem; color: var(--ink-3); margin-top: 8px; }

/* ---------- Roadmap ---------- */
.road { position: relative; margin: 30px 0 0; padding-left: 40px; }
.road::before { content: ""; position: absolute; left: 11px; top: 8px; bottom: 8px; width: 1px; background: var(--rule-2); }
.road-mod { position: relative; padding: 0 0 34px; }
.road-mod::before { content: ""; position: absolute; left: -35px; top: 6px; width: 13px; height: 13px; border-radius: 50%; border: 1.5px solid var(--rule-2); background: var(--bg); }
.road-mod.complete::before { background: var(--accent); border-color: var(--accent); }
.road-mod.current::before { border-color: var(--accent); background: var(--accent-soft); }
.road-mod h3 { font-family: var(--font-display); font-weight: 400; font-size: 1.5rem; margin: 0 0 4px; }
.road-mod h3 a { color: var(--ink); }
.road-mod .blurb { color: var(--ink-2); font-size: .92rem; margin: 0 0 10px; max-width: 60ch; }
.road-lessons { display: flex; flex-wrap: wrap; gap: 6px; }
.road-lessons a { font-size: .78rem; padding: 3px 9px; border: 1px solid var(--rule); border-radius: 999px; color: var(--ink-2); }
.road-lessons a:hover { border-color: var(--accent-line); color: var(--accent); text-decoration: none; }
.road-lessons a.done { background: var(--accent-soft); border-color: var(--accent-line); color: var(--accent); }

/* ---------- Glossary ---------- */
.filter-bar { display: flex; gap: 10px; align-items: center; margin: 20px 0; }
.filter-bar input { flex: 1; max-width: 420px; padding: 9px 12px; font: inherit; font-size: .95rem; color: var(--ink); background: var(--bg-2); border: 1px solid var(--rule-2); border-radius: var(--radius); }
.filter-bar input:focus { outline: none; border-color: var(--accent); }
.gloss-letter { font-family: var(--font-display); font-size: 2rem; color: var(--ink-3); margin: 30px 0 8px; }
.gloss { display: grid; grid-template-columns: 200px 1fr; gap: 8px 24px; padding: 12px 0; border-bottom: 1px solid var(--rule); }
.gloss b { font-weight: 600; }
.gloss p { margin: 0; color: var(--ink-2); font-size: .94rem; }
.gloss a { font-size: .76rem; font-family: var(--font-mono); }
@media (max-width: 700px) { .gloss { grid-template-columns: 1fr; gap: 4px; } }

/* ---------- Flashcards ---------- */
.fc-stage { max-width: 640px; margin: 30px auto 0; }
.fc-card { min-height: 280px; display: flex; flex-direction: column; justify-content: center; padding: 40px 36px; border: 1px solid var(--rule-2); border-radius: var(--radius); background: var(--bg-2); text-align: center; cursor: pointer; }
.fc-card .term { font-family: var(--font-display); font-size: 2.2rem; line-height: 1.1; }
.fc-card .def { font-size: 1.05rem; color: var(--ink); text-align: left; text-wrap: pretty; }
.fc-card .src { margin-top: 18px; font-size: .76rem; font-family: var(--font-mono); color: var(--ink-3); }
.fc-card .hint { margin-top: 18px; font-size: .78rem; color: var(--ink-3); font-family: var(--font-mono); }
.fc-rate { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin-top: 14px; }
.fc-rate button { padding: 10px 6px; border: 1px solid var(--rule-2); border-radius: var(--radius); font-size: .88rem; }
.fc-rate button small { display: block; font-family: var(--font-mono); font-size: .68rem; color: var(--ink-3); margin-top: 2px; }
.fc-rate button:hover { border-color: var(--accent); color: var(--accent); }
.fc-meta { display: flex; justify-content: space-between; font-family: var(--font-mono); font-size: .74rem; color: var(--ink-3); margin-top: 12px; }
.fc-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 20px; }

/* ---------- Notes page ---------- */
.note-entry { padding: 16px 0; border-bottom: 1px solid var(--rule); }
.note-entry h3 { margin: 0 0 6px; font-size: 1rem; font-weight: 500; }
.note-entry pre { white-space: pre-wrap; font: inherit; font-size: .94rem; color: var(--ink-2); margin: 0; }

/* ---------- Library ---------- */
.lib-cat { margin-top: 36px; }
.lib-cat h2 { font-family: var(--font-display); font-weight: 400; font-size: 1.7rem; margin: 0 0 4px; }
.lib-cat > p { color: var(--ink-2); margin: 0 0 14px; font-size: .92rem; }
.lib-item { display: grid; grid-template-columns: 1fr auto; gap: 4px 16px; padding: 12px 0; border-bottom: 1px solid var(--rule); }
.lib-item a { font-weight: 500; }
.lib-item .by { color: var(--ink-2); font-size: .84rem; }
.lib-item .why { grid-column: 1 / -1; color: var(--ink-2); font-size: .9rem; }
.lib-item .tag { font-family: var(--font-mono); font-size: .68rem; color: var(--ink-3); white-space: nowrap; padding-top: 4px; }

/* ---------- Settings ---------- */
.settings-row { display: grid; grid-template-columns: 220px 1fr; gap: 16px; padding: 18px 0; border-bottom: 1px solid var(--rule); align-items: start; }
.settings-row h3 { margin: 0; font-size: 1rem; font-weight: 500; }
.settings-row p { margin: 4px 0 0; color: var(--ink-2); font-size: .88rem; }
.seg { display: inline-flex; border: 1px solid var(--rule-2); border-radius: var(--radius); overflow: hidden; }
.seg button { padding: 7px 14px; font-size: .86rem; color: var(--ink-2); border-right: 1px solid var(--rule-2); }
.seg button:last-child { border-right: 0; }
.seg button.on { background: var(--accent-soft); color: var(--accent); }
@media (max-width: 700px) { .settings-row { grid-template-columns: 1fr; } }

/* ---------- Palette / modal / toast ---------- */
.palette { position: fixed; inset: 0; z-index: 100; background: rgba(10,12,11,.45); display: flex; align-items: flex-start; justify-content: center; padding: 10vh 16px; }
.palette-box { width: 100%; max-width: 640px; background: var(--bg); border: 1px solid var(--rule-2); border-radius: 4px; box-shadow: 0 20px 60px rgba(0,0,0,.25); overflow: hidden; }
.palette-input { display: flex; align-items: center; gap: 10px; padding: 12px 14px; border-bottom: 1px solid var(--rule); color: var(--ink-2); }
.palette-input input { flex: 1; border: 0; background: none; font: inherit; font-size: 1.05rem; color: var(--ink); outline: none; }
.palette-results { max-height: 60vh; overflow-y: auto; }
.pr { display: grid; grid-template-columns: 1fr; gap: 2px; padding: 10px 16px; border-bottom: 1px solid var(--rule); cursor: pointer; }
.pr:last-child { border-bottom: 0; }
.pr.active, .pr:hover { background: var(--accent-soft); }
.pr .t { font-weight: 500; font-size: .95rem; }
.pr .m { font-family: var(--font-mono); font-size: .7rem; color: var(--ink-3); }
.pr .s { font-size: .82rem; color: var(--ink-2); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.pr mark { background: var(--sel); color: inherit; padding: 0 1px; }
.palette-empty { padding: 26px; text-align: center; color: var(--ink-3); font-style: italic; }
.modal { position: fixed; inset: 0; z-index: 100; background: rgba(10,12,11,.45); display: flex; align-items: center; justify-content: center; padding: 16px; }
.modal-box { width: 100%; max-width: 520px; background: var(--bg); border: 1px solid var(--rule-2); border-radius: 4px; padding: 24px 26px; box-shadow: 0 20px 60px rgba(0,0,0,.25); }
.modal-box h2 { font-family: var(--font-display); font-weight: 400; font-size: 1.6rem; margin: 0 0 12px; }
.modal-close { margin-top: 16px; }
.shortcuts { display: grid; grid-template-columns: auto 1fr; gap: 8px 18px; font-size: .9rem; align-items: center; }
.toast { position: fixed; left: 50%; bottom: 28px; transform: translateX(-50%); z-index: 110; background: var(--ink); color: var(--bg); padding: 10px 16px; border-radius: var(--radius); font-size: .88rem; box-shadow: 0 8px 30px rgba(0,0,0,.2); }

/* ---------- Highlight.js token colours (both themes via tokens) ---------- */
.hljs { color: var(--ink); }
.hljs-comment, .hljs-quote { color: var(--ink-3); font-style: italic; }
.hljs-keyword, .hljs-selector-tag, .hljs-literal { color: var(--accent); font-weight: 500; }
.hljs-string, .hljs-regexp, .hljs-addition { color: var(--warn); }
.hljs-number, .hljs-symbol, .hljs-bullet { color: var(--ink-2); }
.hljs-title, .hljs-title.function_, .hljs-title.class_ { color: var(--ink); font-weight: 500; }
.hljs-built_in, .hljs-type, .hljs-attr, .hljs-params { color: var(--ink); }
.hljs-meta { color: var(--ink-2); }

/* ---------- Responsive ---------- */
@media (max-width: 1180px) {
  .lesson-layout { grid-template-columns: minmax(0, 1fr); max-width: calc(var(--measure) + 4rem); }
  .toc { display: none; }
}
@media (max-width: 860px) {
  .app { grid-template-columns: 1fr; }
  .rail { position: fixed; left: 0; top: 0; bottom: 0; width: min(320px, 88vw); z-index: 90; transform: translateX(-100%); transition: transform .2s ease; box-shadow: none; }
  .rail.open { transform: translateX(0); box-shadow: 0 0 60px rgba(0,0,0,.3); }
  .rail .rail-close { display: inline-flex; }
  .rail-scrim { display: none; position: fixed; inset: 0; z-index: 80; background: rgba(10,12,11,.4); }
  .rail-scrim.open { display: block; }
  .topbar .menu-btn { display: inline-flex; }
  .topbar { padding: 0 16px; }
  .view { padding: 0 16px 60px; }
  .streak { display: none; }
  .pager { grid-template-columns: 1fr; }
  .lesson-row { grid-template-columns: 22px 1fr; }
  .lesson-row .idx, .lesson-row .min { display: none; }
}

/* ---------- Print ---------- */
@media print {
  .rail, .topbar, .progress-line, .toc, .lesson-actions, .pager, .video-play, .copy-btn, .notes-box, .quiz-opts, .palette, .modal, .toast { display: none !important; }
  .app { display: block; }
  .view { padding: 0; }
  body { background: #fff; color: #000; font-size: 11pt; }
  .prose pre { border: 1px solid #999; }
  a { color: #000; text-decoration: underline; }
}