/* NexisyTech Learning — site styles. Brand tokens follow nexisytech.com. */

:root {
  --bg: #ffffff;
  --bg-soft: #f8fafc;
  --panel: #ffffff;
  --panel-2: #f1f5f9;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;
  --text: #0f172a;
  --text-dim: #475569;
  --muted: #64748b;
  --accent: #4f46e5;
  --accent-dark: #4338ca;
  --accent-2: #7c3aed;
  --accent-soft: rgba(79, 70, 229, 0.08);
  --tint: #eef2ff;
  --good: #059669;
  --bad: #dc2626;
  --warn: #d97706;
  --code-bg: #0f172a;
  --code-text: #e2e8f0;
  --shadow: 0 18px 40px -26px rgba(15, 23, 42, 0.35);
  --shadow-lg: 0 30px 60px -32px rgba(79, 70, 229, 0.45);
  --radius: 16px;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-display: 'Space Grotesk', 'Inter', 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, Consolas, monospace;

  /* diagram palette */
  --dg-line: #94a3b8;
  --dg-group: rgba(148, 163, 184, 0.06);
  --k-client-f: #f1f5f9; --k-client-s: #94a3b8;
  --k-service-f: #eef2ff; --k-service-s: #6366f1;
  --k-data-f: #ecfdf5; --k-data-s: #10b981;
  --k-infra-f: #fffbeb; --k-infra-s: #f59e0b;
  --k-queue-f: #f5f3ff; --k-queue-s: #8b5cf6;
  --k-danger-f: #fef2f2; --k-danger-s: #ef4444;
  --k-muted-f: #f8fafc; --k-muted-s: #cbd5e1;
  --k-accent-f: #4f46e5; --k-accent-s: #4338ca; --k-accent-t: #ffffff; --k-accent-sub: #e0e7ff;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0b1020; --bg-soft: #0f1629; --panel: #121a2e; --panel-2: #18223a;
    --border: #243049; --border-strong: #33415f;
    --text: #f1f5f9; --text-dim: #c3cee0; --muted: #94a3b8;
    --accent: #818cf8; --accent-dark: #6366f1; --accent-2: #a78bfa;
    --accent-soft: rgba(129, 140, 248, 0.12); --tint: #1b2142;
    --good: #34d399; --bad: #f87171; --warn: #fbbf24;
    --code-bg: #070b16; --shadow: 0 18px 40px -26px rgba(0, 0, 0, 0.8); --shadow-lg: 0 30px 60px -32px rgba(99, 102, 241, 0.5);
    --dg-line: #64748b; --dg-group: rgba(148, 163, 184, 0.05);
    --k-client-f: #1a2338; --k-client-s: #64748b;
    --k-service-f: #1c2150; --k-service-s: #818cf8;
    --k-data-f: #0f2c27; --k-data-s: #34d399;
    --k-infra-f: #2d2412; --k-infra-s: #fbbf24;
    --k-queue-f: #251c45; --k-queue-s: #a78bfa;
    --k-danger-f: #34171c; --k-danger-s: #f87171;
    --k-muted-f: #141b2d; --k-muted-s: #3b4863;
    --k-accent-f: #6366f1; --k-accent-s: #818cf8; --k-accent-t: #ffffff; --k-accent-sub: #e0e7ff;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0b1020; --bg-soft: #0f1629; --panel: #121a2e; --panel-2: #18223a;
  --border: #243049; --border-strong: #33415f;
  --text: #f1f5f9; --text-dim: #c3cee0; --muted: #94a3b8;
  --accent: #818cf8; --accent-dark: #6366f1; --accent-2: #a78bfa;
  --accent-soft: rgba(129, 140, 248, 0.12); --tint: #1b2142;
  --good: #34d399; --bad: #f87171; --warn: #fbbf24;
  --code-bg: #070b16; --shadow: 0 18px 40px -26px rgba(0, 0, 0, 0.8); --shadow-lg: 0 30px 60px -32px rgba(99, 102, 241, 0.5);
  --dg-line: #64748b; --dg-group: rgba(148, 163, 184, 0.05);
  --k-client-f: #1a2338; --k-client-s: #64748b;
  --k-service-f: #1c2150; --k-service-s: #818cf8;
  --k-data-f: #0f2c27; --k-data-s: #34d399;
  --k-infra-f: #2d2412; --k-infra-s: #fbbf24;
  --k-queue-f: #251c45; --k-queue-s: #a78bfa;
  --k-danger-f: #34171c; --k-danger-s: #f87171;
  --k-muted-f: #141b2d; --k-muted-s: #3b4863;
  --k-accent-f: #6366f1; --k-accent-s: #818cf8; --k-accent-t: #ffffff; --k-accent-sub: #e0e7ff;
  color-scheme: dark;
}

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.65 var(--font-body); overflow-x: hidden; }
h1, h2, h3 { font-family: var(--font-display); line-height: 1.15; letter-spacing: -0.02em; margin: 0 0 0.5em; }
h1 { font-size: clamp(2.1rem, 5vw, 3.6rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2.05rem); }
h3 { font-size: 1.15rem; }
p { margin: 0 0 1em; }
a { color: var(--accent); }
img, svg { max-width: 100%; }
code { font-family: var(--font-mono); font-size: 0.88em; background: var(--accent-soft); color: var(--text); padding: 0.1em 0.35em; border-radius: 6px; }
button, input, select { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 6px; }
.container { width: 100%; max-width: 1180px; margin: 0 auto; padding: 0 24px; }
.narrow { max-width: 860px; }
.muted { color: var(--muted); }
.small { font-size: 0.85rem; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--accent); color: #fff; padding: 8px 14px; border-radius: 8px; z-index: 100; }
.skip:focus { left: 8px; }
.eyebrow { display: inline-block; font-size: 0.78rem; font-weight: 700; letter-spacing: 0.12em; text-transform: uppercase; color: var(--accent); margin-bottom: 0.8rem; }
.lead { font-size: 1.15rem; color: var(--text-dim); max-width: 46rem; }
.grad { background: linear-gradient(100deg, var(--accent), var(--accent-2)); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* ---------- buttons ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 0.4rem; padding: 0.7rem 1.2rem; border-radius: 12px; font-weight: 600; text-decoration: none; border: 1px solid transparent; cursor: pointer; transition: transform .15s, background .15s, border-color .15s; white-space: nowrap; }
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: linear-gradient(120deg, #4f46e5, #7c3aed); color: #fff; box-shadow: var(--shadow-lg); }
.btn-ghost { background: var(--panel); color: var(--text); border-color: var(--border-strong); }
.btn-ghost:hover { border-color: var(--accent); }
.btn-small { padding: 0.4rem 0.8rem; font-size: 0.85rem; border-radius: 10px; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }
.icon-btn { width: 40px; height: 40px; display: grid; place-items: center; border-radius: 10px; border: 1px solid var(--border); background: var(--panel); cursor: pointer; }
.icon-btn svg { width: 20px; height: 20px; fill: none; stroke: var(--text); stroke-width: 2; stroke-linecap: round; }

/* ---------- header ---------- */
.site-header { position: sticky; top: 0; z-index: 50; background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(14px); border-bottom: 1px solid var(--border); }
.header-inner { display: flex; align-items: center; gap: 24px; min-height: 68px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--text); }
.brand .logo { width: 36px; height: 36px; flex: none; }
.brand strong { display: block; font-family: var(--font-display); font-size: 1.05rem; line-height: 1.1; }
.brand strong em { font-style: normal; color: var(--accent); }
.brand small { display: block; font-size: 0.7rem; color: var(--muted); letter-spacing: 0.04em; }
.main-nav { display: flex; gap: 4px; margin-left: auto; }
.main-nav a { padding: 0.5rem 0.8rem; border-radius: 10px; color: var(--text-dim); text-decoration: none; font-weight: 500; font-size: 0.95rem; }
.main-nav a:hover, .main-nav a[aria-current="page"] { color: var(--accent); background: var(--accent-soft); }
.header-actions { display: flex; gap: 8px; }
.menu-btn { display: none; }
.i-moon { display: none; }
:root[data-theme="dark"] .i-sun { display: none; }
:root[data-theme="dark"] .i-moon { display: block; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .i-sun { display: none; }
  :root:not([data-theme="light"]) .i-moon { display: block; }
}

/* ---------- hero ---------- */
.hero { padding: 72px 0 56px; background: radial-gradient(900px 420px at 85% -10%, var(--accent-soft), transparent 70%); }
.hero-grid { display: grid; grid-template-columns: 1.05fr 1fr; gap: 48px; align-items: center; }
.hero-art { background: var(--panel); border: 1px solid var(--border); border-radius: 22px; padding: 18px; box-shadow: var(--shadow); }
.hero-art svg { width: 100%; height: auto; display: block; }
.hero-search { display: flex; align-items: center; gap: 8px; background: var(--panel); border: 1px solid var(--border-strong); border-radius: 14px; padding: 6px 6px 6px 14px; max-width: 34rem; margin: 1.6rem 0 1rem; box-shadow: var(--shadow); }
.hero-search svg, .search-box svg { width: 20px; height: 20px; flex: none; fill: none; stroke: var(--muted); stroke-width: 2; stroke-linecap: round; }
.hero-search input { flex: 1; min-width: 0; border: 0; background: transparent; outline: none; padding: 0.5rem 0; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.stats { display: flex; gap: 32px; flex-wrap: wrap; margin: 2rem 0 0; }
.stats div { margin: 0; }
.stats dt { font-family: var(--font-display); font-size: 1.8rem; font-weight: 700; line-height: 1; }
.stats dd { margin: 0.25rem 0 0; color: var(--muted); font-size: 0.85rem; }

.page-hero { padding: 56px 0 36px; background: radial-gradient(800px 300px at 90% -20%, var(--accent-soft), transparent 70%); border-bottom: 1px solid var(--border); }
.page-hero.center { text-align: center; padding: 96px 0; }
.page-hero.center .lead { margin: 0 auto 1.5rem; }
.page-hero.center .hero-actions { justify-content: center; }

/* ---------- sections ---------- */
.section { padding: 72px 0; }
.section-alt { background: var(--bg-soft); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-head { display: flex; justify-content: space-between; align-items: flex-end; gap: 20px; margin-bottom: 28px; }
.section-head p { color: var(--text-dim); margin: 0; }
.h-sm { font-size: 1.4rem; margin-bottom: 20px; }

.path-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.path-card, .topic-card, .feature-card { display: flex; flex-direction: column; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px; text-decoration: none; color: var(--text); transition: transform .18s, border-color .18s, box-shadow .18s; }
.path-card:hover, .topic-card:hover, .feature-card:hover { transform: translateY(-3px); border-color: var(--accent); box-shadow: var(--shadow); }
.path-card p, .topic-card p, .feature-card p { color: var(--text-dim); font-size: 0.95rem; flex: 1; }
.path-num { display: inline-grid; place-items: center; width: 40px; height: 40px; border-radius: 12px; background: var(--tint); color: var(--accent); font-family: var(--font-display); font-weight: 700; margin-bottom: 14px; flex: none; }
.path-meta { font-size: 0.85rem; color: var(--muted); }
.path-progress { display: block; height: 5px; border-radius: 9px; background: var(--panel-2); margin-top: 12px; overflow: hidden; }
.path-progress span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, #4f46e5, #7c3aed); transition: width .3s; }

.card-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.card-top { display: flex; justify-content: space-between; align-items: center; gap: 8px; margin-bottom: 12px; }
.chip { display: inline-flex; align-items: center; font-size: 0.75rem; font-weight: 600; padding: 0.2rem 0.6rem; border-radius: 999px; background: var(--accent-soft); color: var(--accent); white-space: nowrap; }
.learned-badge { display: none; font-size: 0.75rem; font-weight: 700; color: var(--good); }
.topic-card.is-learned { border-color: color-mix(in srgb, var(--good) 45%, var(--border)); }
.topic-card.is-learned .learned-badge { display: inline; }
.card-meta { display: flex; gap: 12px; align-items: center; font-size: 0.82rem; color: var(--muted); }
.level { font-weight: 600; padding: 0.1rem 0.5rem; border-radius: 6px; font-size: 0.78rem; }
.level-beginner { background: color-mix(in srgb, var(--good) 14%, transparent); color: var(--good); }
.level-intermediate { background: color-mix(in srgb, var(--warn) 16%, transparent); color: var(--warn); }
.level-advanced { background: color-mix(in srgb, var(--bad) 14%, transparent); color: var(--bad); }

.sim-band { display: grid; grid-template-columns: 1.1fr 1fr; gap: 40px; align-items: center; padding: 44px; border-radius: 24px; background: linear-gradient(130deg, #312e81, #4f46e5 55%, #7c3aed); color: #fff; box-shadow: var(--shadow-lg); }
.sim-band .eyebrow { color: #c7d2fe; }
.sim-band p { color: #e0e7ff; }
.sim-band .btn-primary { background: #fff; color: #312e81; }
.sim-steps { list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; counter-reset: s; }
.sim-steps li { background: rgba(255, 255, 255, 0.1); border: 1px solid rgba(255, 255, 255, 0.2); border-radius: 14px; padding: 14px 16px 14px 56px; position: relative; counter-increment: s; }
.sim-steps li::before { content: counter(s); position: absolute; left: 16px; top: 14px; width: 28px; height: 28px; border-radius: 8px; background: #fff; color: #4f46e5; display: grid; place-items: center; font-weight: 700; }
.sim-steps strong { display: block; }
.sim-steps span { color: #e0e7ff; font-size: 0.9rem; }

.how-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 18px; }
.how { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px; }
.how span { display: inline-grid; place-items: center; width: 34px; height: 34px; border-radius: 10px; background: linear-gradient(120deg, #4f46e5, #7c3aed); color: #fff; font-weight: 700; margin-bottom: 12px; }
.how p { color: var(--text-dim); font-size: 0.95rem; margin: 0; }
.two-up { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.feature-card { padding: 30px; }
.feature-card .link { color: var(--accent); font-weight: 600; }

/* ---------- topics index ---------- */
.toolbar { display: flex; gap: 14px; flex-wrap: wrap; align-items: center; margin-top: 1.5rem; }
.search-box { display: flex; align-items: center; gap: 10px; flex: 1; min-width: 240px; max-width: 520px; background: var(--panel); border: 1px solid var(--border-strong); border-radius: 12px; padding: 0 14px; }
.search-box input { flex: 1; min-width: 0; border: 0; background: transparent; outline: none; padding: 0.75rem 0; }
.progress-pill { font-size: 0.9rem; font-weight: 600; color: var(--good); background: color-mix(in srgb, var(--good) 12%, transparent); padding: 0.5rem 0.9rem; border-radius: 999px; }
.filter-row { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 18px; }
.filter-chip { border: 1px solid var(--border-strong); background: var(--panel); border-radius: 999px; padding: 0.4rem 0.9rem; font-size: 0.88rem; cursor: pointer; }
.filter-chip[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: #fff; }
.topics-wrap { padding: 40px 24px 72px; }
.cat-section { margin-bottom: 48px; scroll-margin-top: 90px; }
.cat-head { display: flex; gap: 14px; align-items: flex-start; margin-bottom: 18px; }
.cat-head h2 { margin-bottom: 0.2rem; }
.cat-head p { color: var(--text-dim); margin: 0; }
.empty { text-align: center; color: var(--muted); padding: 40px; border: 1px dashed var(--border-strong); border-radius: var(--radius); }

/* ---------- topic page ---------- */
.topic-hero h1 { font-size: clamp(1.9rem, 4.4vw, 3rem); max-width: 52rem; }
.crumbs { display: flex; gap: 8px; font-size: 0.88rem; margin-bottom: 1rem; color: var(--muted); flex-wrap: wrap; }
.crumbs a { color: var(--text-dim); text-decoration: none; }
.crumbs a:hover { color: var(--accent); }
.topic-meta { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; color: var(--muted); font-size: 0.9rem; }
.learn-btn[aria-pressed="true"] { background: var(--good); border-color: var(--good); color: #fff; }
.topic-layout { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 48px; padding-top: 40px; padding-bottom: 56px; }
.toc { position: sticky; top: 90px; align-self: start; display: flex; flex-direction: column; gap: 2px; border-left: 2px solid var(--border); padding-left: 14px; }
.toc h2 { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); font-family: var(--font-body); margin-bottom: 8px; }
.toc a { color: var(--text-dim); text-decoration: none; font-size: 0.9rem; padding: 4px 0; }
.toc a:hover, .toc a.active { color: var(--accent); }
.prose { min-width: 0; }
.prose > section { margin-bottom: 44px; scroll-margin-top: 90px; }
.prose > section > p, .prose li { color: var(--text-dim); }
.prose h2 { font-size: 1.55rem; }
.prose h3 { margin-top: 1.4rem; }
.prose ul { padding-left: 1.2rem; }
.prose li { margin-bottom: 0.4rem; }
.prose strong { color: var(--text); }

.figure { margin: 0; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.figure-scroll { overflow-x: auto; padding: 20px; -webkit-overflow-scrolling: touch; }
.figure figcaption { border-top: 1px solid var(--border); padding: 12px 20px; font-size: 0.9rem; color: var(--muted); background: var(--bg-soft); }
svg.diagram { display: block; width: 100%; height: auto; min-width: var(--dg-min, 600px); font-family: var(--font-body); }
.hero-art svg.diagram { min-width: 0; }

/* diagram parts */
.dg-node { --f: var(--k-service-f); --s: var(--k-service-s); --t: var(--text); --ts: var(--muted); }
.dg-node.k-client { --f: var(--k-client-f); --s: var(--k-client-s); }
.dg-node.k-data { --f: var(--k-data-f); --s: var(--k-data-s); }
.dg-node.k-infra { --f: var(--k-infra-f); --s: var(--k-infra-s); }
.dg-node.k-queue { --f: var(--k-queue-f); --s: var(--k-queue-s); }
.dg-node.k-danger { --f: var(--k-danger-f); --s: var(--k-danger-s); }
.dg-node.k-muted { --f: var(--k-muted-f); --s: var(--k-muted-s); --t: var(--muted); }
.dg-node.k-accent { --f: var(--k-accent-f); --s: var(--k-accent-s); --t: var(--k-accent-t); --ts: var(--k-accent-sub); }
.dg-box { fill: var(--f); stroke: var(--s); stroke-width: 1.5; }
.k-muted .dg-box { stroke-dasharray: 5 4; }
.dg-rim { fill: none; stroke: var(--s); stroke-width: 1.5; }
.dg-label { fill: var(--t); font-size: 13px; font-weight: 600; text-anchor: middle; dominant-baseline: middle; }
.dg-sub { fill: var(--ts); font-size: 11px; text-anchor: middle; dominant-baseline: middle; }
.dg-edge { fill: none; stroke: var(--dg-line); stroke-width: 1.6; }
.dg-edge.dashed { stroke-dasharray: 6 5; }
.dg-head { fill: var(--dg-line); }
.dg-elabel-bg { fill: var(--panel); stroke: var(--border); }
.dg-elabel { fill: var(--text-dim); font-size: 11px; font-weight: 500; text-anchor: middle; }
.dg-group { fill: var(--dg-group); stroke: var(--border-strong); stroke-dasharray: 4 4; }
.dg-group-label { fill: var(--muted); font-size: 12px; font-weight: 600; }
.dg-note { fill: var(--muted); font-size: 12px; }

.steps { counter-reset: st; list-style: none; padding: 0 !important; }
.steps li { counter-increment: st; position: relative; padding: 0 0 14px 46px; }
.steps li::before { content: counter(st); position: absolute; left: 0; top: 0; width: 30px; height: 30px; border-radius: 9px; background: var(--tint); color: var(--accent); font-weight: 700; display: grid; place-items: center; font-size: 0.9rem; }
.concepts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; margin: 0; }
.concepts div { background: var(--panel); border: 1px solid var(--border); border-radius: 14px; padding: 16px 18px; }
.concepts dt { font-weight: 700; margin-bottom: 0.3rem; }
.concepts dd { margin: 0; color: var(--text-dim); font-size: 0.95rem; }
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-bottom: 16px; }
.box { border: 1px solid var(--border); border-radius: 14px; padding: 18px 20px; background: var(--panel); border-top: 3px solid var(--accent); }
.box h3 { margin-top: 0 !important; font-size: 1rem; }
.box ul { margin: 0; }
.box-good { border-top-color: var(--good); }
.box-bad { border-top-color: var(--bad); }
.box-warn { border-top-color: var(--warn); }

.qa { display: grid; gap: 10px; }
.qa details { border: 1px solid var(--border); border-radius: 14px; background: var(--panel); }
.qa summary { cursor: pointer; list-style: none; padding: 16px 18px; font-weight: 600; display: flex; gap: 12px; align-items: baseline; }
.qa summary::-webkit-details-marker { display: none; }
.qa summary::after { content: '+'; margin-left: auto; color: var(--accent); font-size: 1.3rem; line-height: 1; }
.qa details[open] summary::after { content: '−'; }
.q-num { flex: none; font-size: 0.75rem; font-weight: 700; color: var(--accent); background: var(--accent-soft); border-radius: 6px; padding: 0.1rem 0.45rem; }
.answer { padding: 0 18px 18px 18px; color: var(--text-dim); border-top: 1px dashed var(--border); padding-top: 14px; margin: 0 18px; padding-left: 0; padding-right: 0; }

.code { border-radius: 14px; overflow: hidden; background: var(--code-bg); border: 1px solid var(--border); }
.code-head { display: flex; justify-content: space-between; align-items: center; padding: 10px 16px; color: #94a3b8; font-size: 0.85rem; border-bottom: 1px solid rgba(148, 163, 184, 0.2); }
.copy-btn { background: transparent; border: 1px solid rgba(148, 163, 184, 0.4); color: #cbd5e1; border-radius: 8px; padding: 0.15rem 0.6rem; cursor: pointer; font-size: 0.8rem; }
.code pre { margin: 0; padding: 16px; overflow-x: auto; }
.code code { background: none; color: var(--code-text); padding: 0; font-size: 0.85rem; line-height: 1.6; }

.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: 14px; }
table { width: 100%; border-collapse: collapse; font-size: 0.92rem; }
th, td { text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--border); vertical-align: top; }
thead th { background: var(--bg-soft); font-weight: 700; }
tbody th { font-weight: 600; color: var(--text); }
td { color: var(--text-dim); }
tr:last-child th, tr:last-child td { border-bottom: 0; }

.widget { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }
.widget-controls { display: flex; gap: 20px; flex-wrap: wrap; }
.widget-controls label, .field { display: flex; flex-direction: column; gap: 6px; font-size: 0.85rem; color: var(--muted); font-weight: 600; }
select { background: var(--panel); border: 1px solid var(--border-strong); border-radius: 10px; padding: 0.55rem 0.7rem; }
input[type="range"] { accent-color: var(--accent); width: 220px; max-width: 100%; }
.widget-result { margin: 16px 0 10px; color: var(--text-dim); }
.widget-result strong { font-family: var(--font-display); font-size: 1.8rem; color: var(--accent); margin-right: 6px; }
.bigo-blocks { display: flex; flex-wrap: wrap; gap: 3px; min-height: 14px; margin-bottom: 10px; }
.bigo-blocks i { width: 10px; height: 10px; border-radius: 3px; background: linear-gradient(120deg, #4f46e5, #7c3aed); }
.bigo-blocks span { font-size: 0.8rem; color: var(--muted); margin-left: 6px; }

.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; padding-top: 36px; padding-bottom: 56px; }
.pager-link { display: flex; flex-direction: column; gap: 4px; border: 1px solid var(--border); border-radius: 14px; padding: 16px 18px; text-decoration: none; color: var(--text); background: var(--panel); }
.pager-link:hover { border-color: var(--accent); }
.pager-link.next { text-align: right; }
.pager-link small { color: var(--muted); }
.pager-link span { font-weight: 600; }

/* ---------- simulation ---------- */
.sim-layout { display: grid; grid-template-columns: minmax(0, 1.55fr) minmax(280px, 1fr); gap: 20px; align-items: start; padding-top: 32px; padding-bottom: 32px; }
.panel { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px; min-width: 0; }
.sim-top { display: flex; flex-wrap: wrap; gap: 16px; align-items: flex-end; justify-content: space-between; }
.sim-top .field { flex: 1; min-width: 240px; }
.sim-controls { display: flex; flex-wrap: wrap; gap: 8px; }
.sim-progress { display: flex; align-items: center; gap: 12px; margin: 18px 0 16px; font-size: 0.85rem; color: var(--muted); font-weight: 600; }
.sim-progress .bar { flex: 1; height: 6px; border-radius: 9px; background: var(--panel-2); overflow: hidden; }
.sim-progress .bar span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, #4f46e5, #7c3aed); transition: width .25s; }
.flow { list-style: none; margin: 0 0 12px; padding: 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; counter-reset: f; }
.flow li { counter-increment: f; }
.flow button { width: 100%; height: 100%; min-height: 92px; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 4px; text-align: center; padding: 12px 8px; border-radius: 12px; border: 1px solid var(--border); background: var(--bg-soft); cursor: pointer; position: relative; transition: .2s; }
.flow button::before { content: counter(f); position: absolute; top: 6px; left: 8px; font-size: 0.7rem; color: var(--muted); font-weight: 700; }
.flow .ico { font-size: 1.4rem; }
.flow strong { font-size: 0.85rem; line-height: 1.2; }
.flow small { font-size: 0.72rem; color: var(--muted); }
.flow .done button { border-color: color-mix(in srgb, var(--good) 45%, var(--border)); background: color-mix(in srgb, var(--good) 7%, var(--panel)); }
.flow .active button { border: 2px solid var(--accent); background: var(--tint); box-shadow: 0 0 0 4px var(--accent-soft); }
.sim-detail { position: sticky; top: 90px; }
.sim-detail h2 { font-size: 1.45rem; margin-top: 12px; }
.sim-detail > p { color: var(--text-dim); }
.callout { border-left: 3px solid var(--accent); background: var(--accent-soft); border-radius: 0 12px 12px 0; padding: 12px 14px; margin-top: 14px; }
.callout p { margin: 0.3rem 0 0; color: var(--text-dim); font-size: 0.93rem; }
.callout-tip { border-left-color: var(--warn); background: color-mix(in srgb, var(--warn) 9%, transparent); }

/* ---------- interview & cheat sheet ---------- */
.narrow.prose { padding-top: 40px; padding-bottom: 56px; }
.framework { list-style: none; padding: 0 !important; counter-reset: fw; display: grid; gap: 12px; }
.framework li { counter-increment: fw; background: var(--panel); border: 1px solid var(--border); border-radius: 14px; padding: 16px 18px 6px 62px; position: relative; }
.framework li::before { content: counter(fw); position: absolute; left: 18px; top: 16px; width: 30px; height: 30px; border-radius: 9px; background: linear-gradient(120deg, #4f46e5, #7c3aed); color: #fff; font-weight: 700; display: grid; place-items: center; }
.fw-head { display: flex; justify-content: space-between; gap: 12px; align-items: center; }
.fw-head h3 { margin: 0 !important; }
.practice { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.practice-item { border: 1px solid var(--border); border-radius: 14px; padding: 16px 18px; background: var(--panel); }
.practice-item h3 { margin: 0 0 0.4rem !important; font-size: 1rem; }
.practice-item p { margin: 0; font-size: 0.9rem; color: var(--text-dim); }
.cheat-grid { columns: 3 300px; column-gap: 18px; padding-top: 36px; padding-bottom: 56px; }
.cheat { break-inside: avoid; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px; margin-bottom: 18px; border-top: 3px solid var(--accent); }
.cheat h2 { font-size: 1.15rem; }
.cheat dl { margin: 0; display: grid; gap: 10px; }
.cheat dt { font-weight: 700; font-size: 0.95rem; }
.cheat dt a { color: var(--accent); text-decoration: none; }
.cheat dt a:hover { text-decoration: underline; }
.cheat dd { margin: 0; font-size: 0.88rem; color: var(--text-dim); }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--border); background: var(--bg-soft); padding: 48px 0 24px; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 32px; }
.footer-grid h3 { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); font-family: var(--font-body); }
.footer-grid div > a { display: block; color: var(--text-dim); text-decoration: none; font-size: 0.92rem; padding: 3px 0; }
.footer-grid div > a:hover { color: var(--accent); }
.footer-brand p { color: var(--text-dim); font-size: 0.92rem; margin-top: 14px; max-width: 26rem; }
.footer-base { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; margin-top: 36px; padding-top: 20px; border-top: 1px solid var(--border); color: var(--muted); font-size: 0.85rem; }

/* ---------- responsive ---------- */
@media (max-width: 1000px) {
  .hero-grid { grid-template-columns: minmax(0, 1fr); }
  .path-grid, .card-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .how-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .topic-layout { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .toc { display: none; }
  .sim-layout { grid-template-columns: minmax(0, 1fr); }
  .sim-detail { position: static; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 760px) {
  .menu-btn { display: grid; }
  .main-nav { display: none; position: absolute; top: 68px; left: 0; right: 0; flex-direction: column; background: var(--bg); border-bottom: 1px solid var(--border); padding: 10px 16px 16px; }
  .main-nav.open { display: flex; }
  .header-actions { margin-left: auto; }
  .brand small { display: none; }
  .sim-band { grid-template-columns: 1fr; padding: 28px 22px; }
  .two-up, .split, .concepts, .practice { grid-template-columns: 1fr; }
  .section-head { flex-direction: column; align-items: flex-start; }
  .flow { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 560px) {
  .container { padding: 0 16px; }
  .topics-wrap { padding: 32px 16px 56px; }
  .hero { padding: 44px 0 40px; }
  .section { padding: 52px 0; }
  .path-grid, .card-grid, .how-grid, .footer-grid { grid-template-columns: 1fr; }
  .hero-search { flex-wrap: wrap; }
  .hero-search .btn { width: 100%; }
  .stats { gap: 20px; }
  .pager { grid-template-columns: 1fr; }
  .pager-link.next { text-align: left; }
  .figure-scroll { padding: 14px; }
}

/* ---------- print ---------- */
@media print {
  .site-header, .site-footer, .toc, .pager, .learn-btn, #print-btn, .skip { display: none !important; }
  body { background: #fff; color: #000; }
  .page-hero { padding: 0 0 12px; background: none; }
  .cheat-grid { columns: 2; padding: 12px 0; }
  .cheat, .box, .concepts div, .figure { box-shadow: none; }
  .qa details { break-inside: avoid; }
  a { color: inherit; text-decoration: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; scroll-behavior: auto !important; }
}

/* ---------- architecture page (hosts architecture/app.html) ---------- */
.arch-frame-wrap { background: #050b1a; }
.arch-frame { display: block; width: 100%; height: calc(100vh - 69px); min-height: 560px; border: 0; background: #050b1a; }