/* Learning Hub — one stylesheet, light by default, [data-theme="dark"] for dark. */

:root {
  color-scheme: light;
  --bg: #f4f7fb;
  --surface: #ffffff;
  --surface-2: #eef3f9;
  --surface-3: #e3ebf5;
  --ink: #14243a;
  --muted: #5d7089;
  --line: #d8e2ee;
  --line-strong: #c2d1e2;
  --accent: #1667c4;
  --accent-soft: #e5f0fc;
  --accent-ink: #0f4c8a;
  --flash-back: #0f4c8a;
  --flash-back-ink: #ffffff;
  --good: #16865d;
  --good-bg: #dcfce7;
  --good-line: #16a34a;
  --good-ink: #14532d;
  --bad: #c53a4f;
  --bad-bg: #fee2e2;
  --bad-line: #dc2626;
  --bad-ink: #7f1d1d;
  --warn: #a56300;
  --shadow: 0 1px 2px #14243a0d, 0 6px 20px #14243a0f;
  --radius: 14px;
  --code-bg: #f1f5fa;
  --svg-node: #e7f1fb; --svg-node-line: #2b6b9d;
  --svg-node2: #e5f6f3; --svg-node2-line: #168579;
  --svg-node3: #f0ecff; --svg-node3-line: #7056d9;
  --svg-flow: #1875be; --svg-flow2: #168579;
}

[data-theme="dark"] {
  color-scheme: dark;
  --bg: #08121f;
  --surface: #0f1d2f;
  --surface-2: #13253b;
  --surface-3: #1a3049;
  --ink: #e6eef8;
  --muted: #94a8c0;
  --line: #22384f;
  --line-strong: #2f4c69;
  --accent: #5aa9ff;
  --accent-soft: #14304d;
  --accent-ink: #9ccbff;
  --flash-back: #12466f;
  --flash-back-ink: #f2f8ff;
  --good: #4bd08f;
  --good-bg: #103d2d;
  --good-line: #3fb57c;
  --good-ink: #c9f5dd;
  --bad: #ff8597;
  --bad-bg: #43202a;
  --bad-line: #d9687a;
  --bad-ink: #ffd6dc;
  --warn: #f2b45a;
  --shadow: 0 1px 2px #0006, 0 8px 24px #0005;
  --code-bg: #0a1828;
  --svg-node: #102b46; --svg-node-line: #4c84b2;
  --svg-node2: #153c4d; --svg-node2-line: #65d7e6;
  --svg-node3: #213149; --svg-node3-line: #8fa8ff;
  --svg-flow: #74c3ff; --svg-flow2: #76e5b0;
}

/* Track accents */
[data-accent="cyan"]   { --accent: #0e7f8c; --accent-soft: #e0f5f6; --accent-ink: #0a5d67; }
[data-accent="violet"] { --accent: #6a4fd1; --accent-soft: #efebfd; --accent-ink: #4a33a6; }
[data-accent="purple"] { --accent: #9b3fc4; --accent-soft: #f6eafb; --accent-ink: #722b92; }
[data-theme="dark"] [data-accent="cyan"]   { --accent: #4fd2dc; --accent-soft: #0f3540; --accent-ink: #a3eef3; }
[data-theme="dark"] [data-accent="violet"] { --accent: #a796ff; --accent-soft: #241f4a; --accent-ink: #d3caff; }
[data-theme="dark"] [data-accent="purple"] { --accent: #d18bf2; --accent-soft: #33193f; --accent-ink: #ecc8fb; }

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
[x-cloak] { display: none !important; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 15px/1.6 Inter, "Segoe UI", system-ui, -apple-system, Roboto, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3 { line-height: 1.2; margin: 0 0 .4em; letter-spacing: -.01em; }
h1 { font-size: clamp(28px, 4vw, 40px); }
h2 { font-size: 22px; }
h3 { font-size: 16px; }
p { margin: 0 0 .8em; }
button { font: inherit; color: inherit; }
.eyebrow { margin: 0 0 6px; font-size: 12px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; color: var(--accent); }
.lead { font-size: 17px; color: var(--muted); max-width: 760px; }
.muted { color: var(--muted); }
.tiny, small { font-size: 12px; color: var(--muted); }
.spacer { flex: 1; }

.btn {
  border: 1px solid var(--line-strong); background: var(--surface); color: var(--ink);
  border-radius: 10px; padding: 8px 14px; font-weight: 600; cursor: pointer; white-space: nowrap;
}
.btn:hover { background: var(--surface-2); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
[data-theme="dark"] .btn.primary { color: #06101d; }
.btn.primary:hover { filter: brightness(1.08); }
.icon-btn {
  width: 38px; height: 38px; border-radius: 10px; border: 1px solid var(--line); background: var(--surface);
  cursor: pointer; font-size: 17px; display: grid; place-items: center; flex: none;
}
.icon-btn:hover { background: var(--surface-2); }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 30; height: 60px; display: flex; align-items: center; gap: 14px;
  padding: 0 20px; background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: blur(10px); border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 9px; font-weight: 800; color: var(--ink); white-space: nowrap; }
.brand:hover { text-decoration: none; }
.brand-mark { color: var(--accent); font-size: 18px; }
.search { position: relative; flex: 1; max-width: 460px; margin-left: auto; }
.search input {
  width: 100%; height: 38px; padding: 0 12px; border-radius: 10px; border: 1px solid var(--line);
  background: var(--surface-2); color: var(--ink); font: inherit; outline: none;
}
.search input:focus { border-color: var(--accent); background: var(--surface); }
.search-results {
  position: absolute; top: 44px; left: 0; right: 0; background: var(--surface); border: 1px solid var(--line);
  border-radius: 12px; box-shadow: var(--shadow); padding: 6px; max-height: 70vh; overflow: auto;
}
.search-hit { display: block; width: 100%; text-align: left; border: 0; background: none; padding: 8px 10px; border-radius: 8px; cursor: pointer; }
.search-hit:hover, .search-hit:focus { background: var(--surface-2); outline: none; }
.hit-title { display: block; font-weight: 600; }
.hit-meta { font-size: 12px; color: var(--muted); }
.search-empty { padding: 10px; color: var(--muted); font-size: 14px; }
.menu-btn { display: none; }

/* ---------- pages ---------- */
.page { max-width: 1180px; margin: 0 auto; padding: 32px clamp(16px, 4vw, 40px) 80px; }
.intro { margin: 8px 0 28px; }
.crumbs { display: flex; flex-wrap: wrap; gap: 8px; font-size: 13px; color: var(--muted); margin-bottom: 18px; }
.crumbs a { color: var(--muted); }
.crumbs a:hover { color: var(--accent); }
.empty, .loading { padding: 60px 0; text-align: center; color: var(--muted); }

/* home */
.track-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 16px; }
.track-card {
  display: flex; flex-direction: column; padding: 22px; border-radius: var(--radius); background: var(--surface);
  border: 1px solid var(--line); box-shadow: var(--shadow); color: var(--ink); transition: transform .15s, border-color .15s;
}
.track-card:hover { text-decoration: none; transform: translateY(-2px); border-color: var(--accent); }
.track-icon { width: 42px; height: 42px; border-radius: 12px; display: grid; place-items: center; font-size: 20px; background: var(--accent-soft); color: var(--accent); margin-bottom: 14px; }
.track-card .muted { flex: 1; font-size: 14px; }
.track-foot { display: flex; align-items: center; gap: 10px; margin-top: 10px; }
.bar { flex: 1; height: 6px; border-radius: 6px; background: var(--surface-3); overflow: hidden; }
.bar span { display: block; height: 100%; background: var(--accent); border-radius: 6px; transition: width .4s; }

/* track */
.group { margin-top: 28px; }
.group-head { margin-bottom: 12px; }
.group-head h2 { margin-bottom: 2px; }
.topic-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 12px; }
.topic-card {
  position: relative; display: block; padding: 18px 18px 16px; border-radius: 12px; background: var(--surface);
  border: 1px solid var(--line); color: var(--ink); transition: border-color .15s;
}
.topic-card:hover { text-decoration: none; border-color: var(--accent); }
.topic-card h3 { margin: 4px 24px 6px 0; }
.topic-card .muted { font-size: 14px; margin: 0; }
.topic-card .score { display: block; margin-top: 8px; color: var(--good); font-weight: 600; }
.topic-card .status { position: absolute; top: 18px; right: 16px; }
.tag { font-size: 11px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--accent); }

.status { width: 10px; height: 10px; border-radius: 50%; flex: none; border: 2px solid var(--line-strong); background: transparent; }
.status.visited { border-color: var(--accent); }
.status.quizzed { border-color: var(--accent); background: var(--accent); }
.status.mastered { border-color: var(--good); background: var(--good); }

/* ---------- topic layout ---------- */
.topic-layout { display: grid; grid-template-columns: 270px minmax(0, 1fr); min-height: calc(100vh - 60px); }
.sidenav {
  position: sticky; top: 60px; height: calc(100vh - 60px); overflow: auto; padding: 20px 14px 40px;
  border-right: 1px solid var(--line); background: var(--surface);
}
.side-track { display: flex; gap: 8px; align-items: center; font-weight: 700; color: var(--ink); padding: 6px 10px 12px; }
.side-group { margin: 16px 10px 6px; font-size: 11px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
.side-link { display: flex; align-items: center; gap: 10px; padding: 7px 10px; border-radius: 8px; color: var(--ink); font-size: 14px; line-height: 1.35; }
.side-link:hover { background: var(--surface-2); text-decoration: none; }
.side-link.active { background: var(--accent-soft); color: var(--accent-ink); font-weight: 600; }
.scrim { display: none; }
.topic-page { max-width: 1040px; width: 100%; margin: 0; }

.hero { padding: 4px 0 18px; }
.hero h1 { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.badge { font-size: 13px; font-weight: 800; padding: 6px 9px; border-radius: 9px; background: var(--accent); color: #fff; letter-spacing: .02em; }
[data-theme="dark"] .badge { color: #06101d; }
.headline { font-size: 19px; font-weight: 600; margin-bottom: .4em; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.chip { font-size: 12px; padding: 5px 10px; border-radius: 999px; background: var(--surface-2); border: 1px solid var(--line); color: var(--ink); }
.chip.strong { background: var(--accent-soft); border-color: transparent; color: var(--accent-ink); font-weight: 600; }

.tabs { position: sticky; top: 60px; z-index: 10; display: flex; gap: 4px; margin: 10px 0 24px; padding: 8px 0; background: var(--bg); border-bottom: 1px solid var(--line); overflow-x: auto; }
.tabs button { border: 0; background: none; padding: 8px 14px; border-radius: 9px; cursor: pointer; font-weight: 600; color: var(--muted); white-space: nowrap; }
.tabs button:hover { color: var(--ink); background: var(--surface-2); }
.tabs button[aria-selected="true"] { color: var(--accent-ink); background: var(--accent-soft); }
.count { font-size: 11px; padding: 1px 7px; border-radius: 999px; background: var(--surface-3); color: var(--muted); margin-left: 4px; }

.block { margin-bottom: 34px; }
.block-head { margin-bottom: 14px; }
.block-head h2 { margin-bottom: 4px; }
.block-head .muted { max-width: 760px; margin: 0; }
.next-step { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; padding: 18px; border-radius: var(--radius); background: var(--surface); border: 1px dashed var(--line-strong); }
.next-step .muted { margin-right: auto; }

/* ---------- migrated content vocabulary ---------- */
.content > :last-child { margin-bottom: 0; }
.content .grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 12px; }
.content .grid:has(.span-4, .span6, .span12) { grid-template-columns: repeat(12, 1fr); }
.content .span-4 { grid-column: span 4; }
.content .span6 { grid-column: span 6; }
.content .span12 { grid-column: span 12; }
.content .grid + .grid { margin-top: 12px; }
.content .card, .content .concept {
  background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 16px 18px;
}
.content .card > :last-child, .content .concept > :last-child { margin-bottom: 0; }
.content .card h3, .content .concept h3 { margin-bottom: 6px; }
.content .card.tip { border-left: 3px solid var(--accent); }
.content .card.vendor { border-left: 3px solid var(--muted); }
.content .card.good, .content .card.decision:first-child { border-left: 3px solid var(--good); }
.content .card.bad, .content .card.decision + .decision { border-left: 3px solid var(--warn); }
.content .concepts { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 12px; }
.content .pill, .content .topic-pill {
  display: inline-block; padding: 5px 11px; margin: 3px 6px 3px 0; border-radius: 999px; font-size: 13px;
  background: var(--accent-soft); color: var(--accent-ink);
}
.content .topic-pill { font-size: 11px; font-weight: 700; padding: 3px 8px; margin-bottom: 8px; }
.content div.flow {
  display: flex; flex-wrap: wrap; align-items: center; gap: 8px; padding: 18px;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
}
.content div.flow .node { padding: 9px 13px; border-radius: 10px; background: var(--accent-soft); color: var(--accent-ink); font-weight: 600; font-size: 14px; }
.content .arrow { color: var(--muted); font-weight: 700; }
.content .callout { margin-top: 12px; padding: 12px 14px; border-left: 3px solid var(--accent); background: var(--surface-2); border-radius: 8px; }
.content .callout.warn { border-left-color: var(--warn); }
.content .kpi { font-size: 26px; font-weight: 800; }
.content .cite, .lead .cite { font-size: 11px; vertical-align: super; margin-left: 2px; }
.content .source, .content .tiny { font-size: 13px; color: var(--muted); margin-top: 8px; }
.content table { width: 100%; border-collapse: collapse; }
.content .card:has(> table) { overflow-x: auto; }
.content th { font-size: 13px; color: var(--muted); white-space: nowrap; }
.content td, .content th { padding: 9px 10px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
.content tr:last-child td { border-bottom: 0; }
.content pre { margin: 0 0 12px; overflow: auto; padding: 14px 16px; border-radius: 10px; background: var(--code-bg); border: 1px solid var(--line); font: 13px/1.5 Consolas, Monaco, monospace; white-space: pre-wrap; }
.content .steps { counter-reset: step; }
.content .step { display: grid; grid-template-columns: 34px 1fr; gap: 12px; padding: 12px 0; border-bottom: 1px solid var(--line); }
.content .step:last-child { border-bottom: 0; }
.content .step::before { counter-increment: step; content: counter(step); width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center; background: var(--accent); color: #fff; font-weight: 800; font-size: 13px; }
[data-theme="dark"] .content .step::before { color: #06101d; }
.content .step strong { display: block; }

/* SVG diagrams */
.content .diagram-wrap { overflow-x: auto; padding: 10px; }
.content svg.diagram { min-width: 720px; width: 100%; height: auto; display: block; }
.content svg .node  { fill: var(--svg-node);  stroke: var(--svg-node-line);  stroke-width: 1.5; }
.content svg .node2 { fill: var(--svg-node2); stroke: var(--svg-node2-line); stroke-width: 1.5; }
.content svg .node3 { fill: var(--svg-node3); stroke: var(--svg-node3-line); stroke-width: 1.5; }
.content svg .svgtext { fill: var(--ink); font-size: 16px; font-weight: 700; }
.content svg .svgsub { fill: var(--muted); font-size: 12px; }
.content svg .flow  { stroke: var(--svg-flow);  stroke-width: 3; fill: none; stroke-dasharray: 8 8; animation: dash 9s linear infinite; }
.content svg .flow2 { stroke: var(--svg-flow2); stroke-width: 3; fill: none; stroke-dasharray: 8 8; animation: dash 8s linear infinite reverse; }
@keyframes dash { to { stroke-dashoffset: -160; } }

/* ---------- flashcards ---------- */
.toolbar { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-bottom: 16px; }
.seg { display: inline-flex; flex-wrap: wrap; gap: 4px; padding: 4px; border-radius: 11px; background: var(--surface-2); }
.seg button { border: 0; background: none; padding: 6px 12px; border-radius: 8px; cursor: pointer; font-weight: 600; font-size: 13px; color: var(--muted); text-transform: capitalize; }
.seg button.on { background: var(--surface); color: var(--ink); box-shadow: var(--shadow); }
.flash-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px; }
.flash { perspective: 1000px; height: 190px; padding: 0; border: 0; background: none; cursor: pointer; text-align: left; }
.flash-inner { position: relative; display: block; width: 100%; height: 100%; transition: transform .5s; transform-style: preserve-3d; }
.flash.flipped .flash-inner { transform: rotateY(180deg); }
.face {
  position: absolute; inset: 0; display: flex; flex-direction: column; justify-content: space-between; gap: 8px;
  padding: 18px; border-radius: var(--radius); backface-visibility: hidden; -webkit-backface-visibility: hidden;
  background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow);
}
.face strong { font-size: 16px; line-height: 1.4; overflow: auto; }
.flash:hover .front { border-color: var(--accent); }
.flash:focus-visible { outline: none; }
.flash:focus-visible .face { outline: 2px solid var(--accent); outline-offset: 2px; }
.back { transform: rotateY(180deg); background: var(--flash-back); border-color: var(--flash-back); color: var(--flash-back-ink); }
.back .tag, .back small { color: color-mix(in srgb, var(--flash-back-ink) 78%, transparent); }

/* ---------- quiz ---------- */
.quiz { display: grid; gap: 14px; }
.question { padding: 18px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); }
.q { display: flex; gap: 10px; font-weight: 600; margin-bottom: 12px; }
.qnum { flex: none; width: 24px; height: 24px; border-radius: 50%; display: grid; place-items: center; font-size: 12px; background: var(--accent-soft); color: var(--accent-ink); }
.options { display: grid; gap: 8px; }
.option {
  display: flex; justify-content: space-between; align-items: center; gap: 12px; text-align: left; width: 100%;
  padding: 11px 14px; border-radius: 10px; border: 1px solid var(--line-strong); background: var(--surface-2);
  color: var(--ink); cursor: pointer; transition: background .15s, border-color .15s;
}
.option:not(:disabled):hover { border-color: var(--accent); background: var(--accent-soft); }
.option:disabled { cursor: default; }
.option.correct { background: var(--good-bg); border-color: var(--good-line); color: var(--good-ink); font-weight: 600; }
.option.wrong { background: var(--bad-bg); border-color: var(--bad-line); color: var(--bad-ink); font-weight: 600; }
.option.dim { opacity: .6; }
.mark { font-weight: 800; }
.scorebar {
  position: sticky; bottom: 16px; display: flex; align-items: center; justify-content: space-between; gap: 12px;
  margin-top: 18px; padding: 14px 18px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow);
}

/* ---------- sources & pager ---------- */
.source-list { display: grid; gap: 10px; padding-left: 22px; }
.source-list li { padding: 4px 0; }
.source-list small { display: block; }
.pager { display: flex; gap: 12px; margin-top: 44px; padding-top: 22px; border-top: 1px solid var(--line); }
.pager-link { display: flex; flex-direction: column; max-width: 48%; padding: 12px 16px; border-radius: 12px; border: 1px solid var(--line); background: var(--surface); color: var(--ink); font-weight: 600; }
.pager-link:hover { text-decoration: none; border-color: var(--accent); }
.pager-link.next { text-align: right; }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .topic-layout { grid-template-columns: minmax(0, 1fr); }
  .menu-btn { display: grid; }
  .sidenav {
    position: fixed; top: 60px; left: 0; bottom: 0; width: 280px; height: auto; z-index: 25;
    transform: translateX(-100%); transition: transform .2s; box-shadow: var(--shadow);
  }
  .nav-open .sidenav { transform: none; }
  .nav-open .scrim { display: block; position: fixed; inset: 60px 0 0; z-index: 20; background: #0005; }
  .content .grid:has(.span-4, .span6, .span12) { grid-template-columns: 1fr; }
  .content .span-4, .content .span6, .content .span12 { grid-column: auto; }
}
@media (max-width: 560px) {
  .topbar { padding: 0 12px; gap: 8px; }
  .brand span:last-child { display: none; }
  .pager { flex-direction: column; }
  .pager-link { max-width: none; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}