/* WindowsCommander — design system & layout. No inline styles are used (strict CSP). */
@font-face { font-family: 'Inter'; src: url('../fonts/inter.woff2') format('woff2'); font-weight: 100 900; font-display: swap; }
@font-face { font-family: 'JetBrains Mono'; src: url('../fonts/jetbrains-mono-latin-400-normal.woff2') format('woff2'); font-weight: 400; font-display: swap; }
@font-face { font-family: 'JetBrains Mono'; src: url('../fonts/jetbrains-mono-latin-600-normal.woff2') format('woff2'); font-weight: 600; font-display: swap; }

:root, [data-theme="ultraviolet"] {
  --bg: #090a14; --bg2: #0d0f1d; --surface: #12152a; --surface2: #181c35; --surface3: #1f2442;
  --line: #262b4a; --line2: #333a60;
  --text: #eef0ff; --muted: #a2a7cc; --dim: #6f7499;
  --accent: #b07aff; --accent2: #7b8cff; --accent-ink: #120a24;
  --ok: #3ddcaa; --warn: #ffc65c; --bad: #ff6b8e; --info: #6fc3ff;
  --glow: rgba(176, 122, 255, .28);
  --grad: linear-gradient(135deg, var(--accent), var(--accent2));
  --shadow: 0 18px 50px rgba(0, 0, 0, .45);
  --code-bg: #0a0c19;
  color-scheme: dark;
}
[data-theme="voltage"] { --accent: #3ee6d0; --accent2: #4aa3ff; --accent-ink: #04201c; --glow: rgba(62, 230, 208, .25); }
[data-theme="citrus"] { --accent: #b9f45f; --accent2: #39d6bf; --accent-ink: #132004; --glow: rgba(185, 244, 95, .22); }
[data-theme="daylight"] {
  --bg: #f5f6fb; --bg2: #eceef7; --surface: #ffffff; --surface2: #f4f5fb; --surface3: #e9ebf6;
  --line: #dfe2f0; --line2: #cbd0e6; --text: #151833; --muted: #4f5578; --dim: #7a7fa0;
  --accent: #6a3ff0; --accent2: #2f6bff; --accent-ink: #ffffff; --glow: rgba(106, 63, 240, .16);
  --ok: #0f9d74; --warn: #b57800; --bad: #d7335c; --info: #1b78c4;
  --shadow: 0 14px 40px rgba(30, 35, 80, .12); --code-bg: #0f1224;
  color-scheme: light;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 15px/1.6 'Inter', system-ui, -apple-system, 'Segoe UI', sans-serif; min-height: 100vh; -webkit-font-smoothing: antialiased; }
body::before { content: ''; position: fixed; inset: 0; pointer-events: none; z-index: -1;
  background: radial-gradient(900px 500px at 85% -10%, var(--glow), transparent 60%), radial-gradient(700px 420px at -10% 20%, color-mix(in srgb, var(--accent2) 14%, transparent), transparent 60%); }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img, svg { display: block; max-width: 100%; }
h1, h2, h3, h4 { line-height: 1.2; margin: 0 0 .5em; letter-spacing: -.015em; }
h1 { font-size: clamp(28px, 4.2vw, 46px); font-weight: 800; }
h2 { font-size: clamp(21px, 2.6vw, 28px); font-weight: 750; }
h3 { font-size: 17px; font-weight: 700; }
p { margin: 0 0 1em; }
code, kbd, pre, .mono { font-family: 'JetBrains Mono', ui-monospace, Consolas, monospace; }
:not(pre) > code { background: var(--surface3); border: 1px solid var(--line); padding: .08em .4em; border-radius: 6px; font-size: .88em; }
kbd { background: var(--surface3); border: 1px solid var(--line2); border-bottom-width: 2px; border-radius: 6px; padding: 1px 6px; font-size: 12px; color: var(--muted); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 6px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: 12px; top: -60px; z-index: 100; background: var(--accent); color: var(--accent-ink); padding: 8px 14px; border-radius: 8px; font-weight: 700; }
.skip:focus { top: 12px; }
.ico { width: 20px; height: 20px; flex: none; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.ico.sm { width: 16px; height: 16px; }
.ico.lg { width: 26px; height: 26px; }

/* ---------- header */
.hdr { position: sticky; top: 0; z-index: 40; background: color-mix(in srgb, var(--bg) 82%, transparent); backdrop-filter: blur(14px); border-bottom: 1px solid var(--line); }
.hdr-in { max-width: 1240px; margin: 0 auto; display: flex; align-items: center; gap: 18px; padding: 10px 22px; }
.brand { display: flex; align-items: center; flex: none; border-radius: 10px; }
.brand img { height: 40px; width: auto; border-radius: 9px; }
[data-theme="daylight"] .brand img { box-shadow: 0 2px 10px rgba(0,0,0,.12); }
.nav { display: flex; gap: 2px; margin-left: 8px; }
.nav a { color: var(--muted); font-weight: 600; font-size: 14px; padding: 8px 13px; border-radius: 10px; display: flex; gap: 7px; align-items: center; }
.nav a:hover { color: var(--text); background: var(--surface2); text-decoration: none; }
.nav a[aria-current="page"] { color: var(--text); background: var(--surface2); box-shadow: inset 0 -2px 0 var(--accent); }
.hdr-actions { margin-left: auto; display: flex; align-items: center; gap: 8px; }
.search-btn { display: flex; align-items: center; gap: 10px; background: var(--surface); border: 1px solid var(--line); color: var(--dim); border-radius: 11px; padding: 7px 10px 7px 12px; min-width: 210px; cursor: pointer; font: inherit; font-size: 13.5px; }
.search-btn:hover { border-color: var(--line2); color: var(--muted); }
.search-btn kbd { margin-left: auto; }
.icon-btn { width: 38px; height: 38px; display: grid; place-items: center; border-radius: 11px; background: var(--surface); border: 1px solid var(--line); color: var(--muted); cursor: pointer; }
.icon-btn:hover { color: var(--text); border-color: var(--line2); }
.xp-chip { display: flex; align-items: center; gap: 8px; padding: 5px 12px 5px 6px; border-radius: 999px; background: var(--surface); border: 1px solid var(--line); color: var(--text); font-size: 13px; font-weight: 650; }
.xp-chip:hover { text-decoration: none; border-color: var(--line2); }
.xp-chip .rank-dot { width: 26px; height: 26px; border-radius: 50%; background: var(--grad); display: grid; place-items: center; color: var(--accent-ink); }
.theme-pop { position: absolute; right: 22px; top: 60px; background: var(--surface); border: 1px solid var(--line2); border-radius: 14px; padding: 10px; box-shadow: var(--shadow); display: grid; gap: 4px; min-width: 210px; }
.theme-pop[hidden] { display: none; }
.theme-pop button { display: flex; align-items: center; gap: 10px; background: none; border: 0; color: var(--text); padding: 8px 10px; border-radius: 9px; cursor: pointer; font: inherit; font-size: 14px; text-align: left; }
.theme-pop button:hover, .theme-pop button[aria-checked="true"] { background: var(--surface2); }
.swatch { width: 22px; height: 22px; border-radius: 7px; border: 1px solid var(--line2); }
.sw-ultraviolet { background: linear-gradient(135deg, #b07aff, #7b8cff); }
.sw-voltage { background: linear-gradient(135deg, #3ee6d0, #4aa3ff); }
.sw-citrus { background: linear-gradient(135deg, #b9f45f, #39d6bf); }
.sw-daylight { background: linear-gradient(135deg, #ffffff, #6a3ff0); }

/* ---------- mobile tab bar */
.tabbar { display: none; }
@media (max-width: 860px) {
  .nav, .search-btn span, .search-btn kbd, .xp-chip span { display: none; }
  .search-btn { min-width: 0; padding: 0; width: 38px; height: 38px; justify-content: center; }
  .xp-chip { padding: 4px; }
  .hdr-in { padding: 9px 14px; gap: 10px; }
  .brand img { height: 34px; }
  .tabbar { display: flex; position: fixed; bottom: 0; left: 0; right: 0; z-index: 45; background: color-mix(in srgb, var(--bg) 92%, transparent); backdrop-filter: blur(14px); border-top: 1px solid var(--line); padding: 6px 6px calc(6px + env(safe-area-inset-bottom)); }
  .tabbar a { flex: 1; display: grid; justify-items: center; gap: 2px; color: var(--dim); font-size: 11px; font-weight: 600; padding: 4px 0; border-radius: 10px; }
  .tabbar a[aria-current="page"] { color: var(--accent); }
  .tabbar a:hover { text-decoration: none; }
  main { padding-bottom: 84px; }
  .theme-pop { right: 10px; }
}

/* ---------- layout */
main { display: block; min-height: 70vh; }
.wrap { max-width: 1240px; margin: 0 auto; padding: 34px 22px 60px; }
.wrap.narrow { max-width: 880px; }
@media (max-width: 600px) { .wrap { padding: 22px 14px 40px; } }
.page-head { margin-bottom: 26px; }
.eyebrow { font: 600 11.5px/1 'JetBrains Mono', monospace; letter-spacing: .14em; text-transform: uppercase; color: var(--accent); margin-bottom: 12px; display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.lead { color: var(--muted); font-size: 17px; max-width: 720px; }
.muted { color: var(--muted); }
.dim { color: var(--dim); }
.crumbs { display: flex; gap: 8px; flex-wrap: wrap; font-size: 13px; color: var(--dim); margin-bottom: 16px; }
.crumbs a { color: var(--muted); }
.grid { display: grid; gap: 16px; }
.g2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.g3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.g4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 1000px) { .g4 { grid-template-columns: repeat(2, minmax(0, 1fr)); } .g3 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 640px) { .g2, .g3, .g4 { grid-template-columns: minmax(0, 1fr); } }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.spacer { flex: 1; }
.section { margin-top: 46px; }
.section-head { display: flex; align-items: end; justify-content: space-between; gap: 16px; margin-bottom: 16px; flex-wrap: wrap; }
.section-head p { margin: 0; color: var(--muted); }

/* ---------- cards & surfaces */
.card { background: var(--surface); border: 1px solid var(--line); border-radius: 18px; padding: 20px; position: relative; }
.card.pad-lg { padding: 28px; }
.card.link { display: block; color: inherit; transition: transform .15s, border-color .15s, background .15s; }
.card.link:hover { text-decoration: none; transform: translateY(-2px); border-color: var(--line2); background: var(--surface2); }
.card h3 { margin-bottom: 6px; }
.card p { color: var(--muted); font-size: 14px; }
.card .foot { display: flex; align-items: center; gap: 10px; margin-top: 14px; font-size: 13px; color: var(--dim); }
.tile-ico { width: 44px; height: 44px; border-radius: 13px; display: grid; place-items: center; background: color-mix(in srgb, var(--accent) 14%, var(--surface2)); color: var(--accent); border: 1px solid color-mix(in srgb, var(--accent) 30%, var(--line)); margin-bottom: 14px; }
.pill { display: inline-flex; align-items: center; gap: 6px; font: 600 11px/1 'JetBrains Mono', monospace; letter-spacing: .06em; text-transform: uppercase; padding: 6px 9px; border-radius: 999px; background: var(--surface3); color: var(--muted); border: 1px solid var(--line); white-space: nowrap; }
.pill.accent { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 40%, var(--line)); background: color-mix(in srgb, var(--accent) 10%, var(--surface)); }
.pill.ok { color: var(--ok); border-color: color-mix(in srgb, var(--ok) 40%, var(--line)); }
.pill.warn { color: var(--warn); border-color: color-mix(in srgb, var(--warn) 40%, var(--line)); }
.pill.bad { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 45%, var(--line)); }
.callout { border: 1px solid var(--line); border-left: 3px solid var(--accent); background: var(--surface2); border-radius: 12px; padding: 14px 16px; font-size: 14px; color: var(--muted); margin: 18px 0; }
.callout b, .callout strong { color: var(--text); }
.callout .ico { display: inline-block; vertical-align: -3px; margin-right: 4px; }
.analysis > :first-child { margin-top: 0; }
.article, .article .body { min-width: 0; overflow-wrap: anywhere; }
.callout.warn { border-left-color: var(--warn); }
.callout.bad { border-left-color: var(--bad); }
.callout.ok { border-left-color: var(--ok); }

/* ---------- buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; font: 650 14px/1 'Inter', sans-serif; padding: 12px 18px; border-radius: 12px; border: 1px solid var(--line2); background: var(--surface2); color: var(--text); cursor: pointer; transition: transform .12s, background .12s, border-color .12s; white-space: nowrap; }
.btn:hover { text-decoration: none; border-color: var(--accent); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--grad); color: var(--accent-ink); border-color: transparent; box-shadow: 0 8px 26px var(--glow); }
.btn.primary:hover { filter: brightness(1.07); }
.btn.ghost { background: transparent; }
.btn.sm { padding: 8px 12px; font-size: 13px; border-radius: 10px; }
.btn.danger { color: var(--bad); }
.btn[disabled] { opacity: .5; cursor: not-allowed; }
.seg { display: inline-flex; background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 4px; gap: 2px; flex-wrap: wrap; }
.seg button { background: none; border: 0; color: var(--muted); font: 600 13.5px 'Inter', sans-serif; padding: 8px 13px; border-radius: 9px; cursor: pointer; }
.seg button[aria-pressed="true"], .seg button[aria-selected="true"] { background: var(--surface3); color: var(--text); box-shadow: inset 0 0 0 1px var(--line2); }

/* ---------- progress bars & rings */
.bar { height: 8px; border-radius: 99px; background: var(--surface3); overflow: hidden; }
.bar > i { display: block; height: 100%; width: 0; background: var(--grad); border-radius: 99px; transition: width .5s ease; }
.bar.thin { height: 5px; }
.ring { --p: 0; width: 54px; height: 54px; border-radius: 50%; display: grid; place-items: center; background: conic-gradient(var(--accent) calc(var(--p) * 1%), var(--surface3) 0); flex: none; }
.ring::after { content: attr(data-label); width: 42px; height: 42px; border-radius: 50%; background: var(--surface); display: grid; place-items: center; font: 650 12px 'JetBrains Mono', monospace; color: var(--text); }

/* ---------- home */
.hero { display: grid; grid-template-columns: 1.15fr .85fr; gap: 34px; align-items: center; padding: 36px 0 10px; }
@media (max-width: 960px) { .hero { grid-template-columns: minmax(0, 1fr); } }
.hero h1 .grad { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero .lead { font-size: 18px; margin: 18px 0 26px; }
.hero-tag { font: 600 13px 'JetBrains Mono', monospace; letter-spacing: .2em; color: var(--accent); text-transform: uppercase; margin-bottom: 16px; }
.term { background: var(--code-bg); border: 1px solid var(--line2); border-radius: 18px; overflow: hidden; box-shadow: var(--shadow), 0 0 0 1px color-mix(in srgb, var(--accent) 10%, transparent); color: #dfe3ff; }
.term-bar { display: flex; align-items: center; gap: 7px; padding: 11px 14px; border-bottom: 1px solid #22284a; background: #0f1226; }
.term-bar i { width: 11px; height: 11px; border-radius: 50%; background: #3a4170; }
.term-bar i:first-child { background: #ff6b8e; } .term-bar i:nth-child(2) { background: #ffc65c; } .term-bar i:nth-child(3) { background: #3ddcaa; }
.term-bar span { margin-left: 8px; font: 600 11px 'JetBrains Mono', monospace; color: #8a90bb; letter-spacing: .1em; }
.term-body { padding: 18px; font: 13px/1.75 'JetBrains Mono', monospace; white-space: pre-wrap; word-break: break-word; }
.t-p { color: #8b93ff; } .t-c { color: #b07aff; } .t-ok { color: #3ddcaa; } .t-w { color: #ffc65c; } .t-d { color: #7c83ad; }
.stats { display: grid; grid-template-columns: repeat(5, 1fr); gap: 12px; margin: 34px 0 0; }
@media (max-width: 800px) { .stats { grid-template-columns: repeat(2, 1fr); } }
.stat { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 16px 18px; }
.stat b { display: block; font-size: 26px; font-weight: 800; letter-spacing: -.02em; }
.stat span { color: var(--dim); font-size: 12.5px; }
.steps4 { counter-reset: s; }
.steps4 .card::before { counter-increment: s; content: '0' counter(s); position: absolute; right: 18px; top: 16px; font: 700 13px 'JetBrains Mono', monospace; color: var(--dim); }
.tier-row { display: grid; grid-template-columns: 220px 1fr; gap: 18px; padding: 18px 0; border-top: 1px solid var(--line); }
.tier-row:first-child { border-top: 0; }
@media (max-width: 760px) { .tier-row { grid-template-columns: minmax(0, 1fr); } }
.tier-label b { display: block; font-size: 17px; }
.tier-label small { color: var(--dim); font-size: 13px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip { display: inline-flex; align-items: center; gap: 8px; padding: 8px 12px; border-radius: 11px; background: var(--surface2); border: 1px solid var(--line); color: var(--text); font-size: 13.5px; font-weight: 550; }
.chip:hover { border-color: var(--accent); text-decoration: none; }
.chip.done { border-color: color-mix(in srgb, var(--ok) 50%, var(--line)); }
.chip.done .ico { color: var(--ok); }
.cta-band { margin-top: 50px; border-radius: 22px; padding: 34px; background: linear-gradient(135deg, color-mix(in srgb, var(--accent) 18%, var(--surface)), color-mix(in srgb, var(--accent2) 16%, var(--surface))); border: 1px solid var(--line2); display: flex; gap: 20px; align-items: center; justify-content: space-between; flex-wrap: wrap; }
.cta-band h2 { margin: 0 0 6px; }
.cta-band p { margin: 0; color: var(--muted); }

/* ---------- learn */
.tier-block { margin-bottom: 38px; }
.tier-block > header { display: flex; align-items: center; gap: 14px; margin-bottom: 14px; flex-wrap: wrap; }
.tier-num { width: 40px; height: 40px; border-radius: 12px; display: grid; place-items: center; font: 800 15px 'JetBrains Mono', monospace; background: var(--grad); color: var(--accent-ink); }
.mod-card { display: flex; flex-direction: column; height: 100%; }
.mod-card .top { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; }
.mod-card p { flex: 1; }
.mod-card .bar { margin-top: 12px; }
.mod-head { display: grid; grid-template-columns: 1fr 300px; gap: 26px; align-items: start; }
@media (max-width: 900px) { .mod-head { grid-template-columns: minmax(0, 1fr); } }
.outcomes { list-style: none; padding: 0; margin: 0; display: grid; gap: 9px; }
.outcomes li { display: flex; gap: 10px; color: var(--muted); font-size: 14px; }
.outcomes .ico { color: var(--ok); margin-top: 2px; }
.lesson-list { display: grid; gap: 10px; }
.lesson-item { display: flex; align-items: center; gap: 14px; padding: 14px 16px; background: var(--surface); border: 1px solid var(--line); border-radius: 14px; color: var(--text); }
.lesson-item:hover { text-decoration: none; border-color: var(--line2); background: var(--surface2); }
.lesson-item .n { width: 32px; height: 32px; border-radius: 10px; display: grid; place-items: center; background: var(--surface3); font: 650 13px 'JetBrains Mono', monospace; color: var(--muted); flex: none; }
.lesson-item.done .n { background: color-mix(in srgb, var(--ok) 18%, var(--surface3)); color: var(--ok); }
.lesson-item b { display: block; font-size: 15px; }
.lesson-item small { color: var(--dim); }
.lesson-item .meta { margin-left: auto; color: var(--dim); font-size: 12.5px; white-space: nowrap; }

/* ---------- lesson reader */
.reader { display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 34px; align-items: start; }
@media (max-width: 980px) { .reader { grid-template-columns: minmax(0, 1fr); } .toc { position: static !important; } }
.toc { position: sticky; top: 84px; background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 14px; }
.toc h4 { font-size: 13px; color: var(--muted); margin: 4px 6px 10px; }
.toc a { display: flex; gap: 10px; align-items: center; padding: 8px 9px; border-radius: 9px; color: var(--muted); font-size: 13.5px; }
.toc a:hover { background: var(--surface2); text-decoration: none; color: var(--text); }
.toc a[aria-current="page"] { background: var(--surface3); color: var(--text); font-weight: 650; }
.toc .dot { width: 18px; height: 18px; border-radius: 50%; border: 2px solid var(--line2); flex: none; display: grid; place-items: center; }
.toc a.done .dot { border-color: var(--ok); background: var(--ok); color: var(--accent-ink); }
.article { max-width: 760px; }
.article h1 { font-size: clamp(26px, 3.4vw, 36px); }
.article .body p { font-size: 16.5px; line-height: 1.75; color: color-mix(in srgb, var(--text) 88%, var(--muted)); }
.keypoints { display: grid; gap: 8px; margin: 22px 0; padding: 18px 20px; border-radius: 16px; background: var(--surface); border: 1px solid var(--line); }
.keypoints h3 { font-size: 13px; color: var(--accent); font-family: 'JetBrains Mono', monospace; letter-spacing: .1em; text-transform: uppercase; margin-bottom: 6px; }
.keypoints div { display: flex; gap: 10px; font-size: 14.5px; }
.keypoints .ico { color: var(--accent); margin-top: 3px; }
.codeblock { margin: 20px 0; border-radius: 14px; overflow: hidden; border: 1px solid var(--line2); background: var(--code-bg); }
.codeblock header { display: flex; align-items: center; gap: 10px; padding: 9px 12px 9px 14px; background: #0f1226; border-bottom: 1px solid #22284a; color: #a9afd6; font-size: 12.5px; }
.codeblock header .pill { background: #1a1f3d; border-color: #2c3360; color: #c9b4ff; }
.codeblock header button { margin-left: auto; background: #1a1f3d; border: 1px solid #2c3360; color: #dfe3ff; border-radius: 8px; padding: 5px 10px; font: 600 12px 'Inter', sans-serif; cursor: pointer; display: flex; gap: 6px; align-items: center; }
.codeblock header button:hover { border-color: var(--accent); }
.codeblock pre { margin: 0; padding: 16px; overflow-x: auto; font-size: 13.2px; line-height: 1.7; color: #e3e6ff; }
.tok-c { color: #6f7aa8; font-style: italic; } .tok-k { color: #c49bff; } .tok-s { color: #8fe3b8; } .tok-v { color: #7fc8ff; } .tok-p { color: #ffc98a; } .tok-n { color: #ff9fb6; }
.check { margin: 28px 0; padding: 22px; border-radius: 18px; border: 1px solid var(--line2); background: linear-gradient(180deg, var(--surface2), var(--surface)); }
.check h3 { display: flex; gap: 10px; align-items: center; }
.opts { display: grid; gap: 10px; margin-top: 14px; }
.opt { text-align: left; display: flex; gap: 12px; align-items: flex-start; padding: 13px 14px; border-radius: 12px; border: 1px solid var(--line2); background: var(--surface); color: var(--text); font: 500 14.5px/1.45 'Inter', sans-serif; cursor: pointer; width: 100%; }
.opt:hover:not([disabled]) { border-color: var(--accent); }
.opt .k { width: 26px; height: 26px; border-radius: 8px; flex: none; display: grid; place-items: center; background: var(--surface3); font: 650 12px 'JetBrains Mono', monospace; color: var(--muted); }
.opt.sel { border-color: var(--accent); background: color-mix(in srgb, var(--accent) 9%, var(--surface)); }
.opt.right { border-color: var(--ok); background: color-mix(in srgb, var(--ok) 11%, var(--surface)); }
.opt.right .k { background: var(--ok); color: #04150f; }
.opt.wrong { border-color: var(--bad); background: color-mix(in srgb, var(--bad) 10%, var(--surface)); }
.opt.wrong .k { background: var(--bad); color: #fff; }
.opt[disabled] { cursor: default; }
.fb { margin-top: 14px; padding: 12px 14px; border-radius: 12px; font-size: 14px; background: var(--surface2); border: 1px solid var(--line); }
.fb.ok { border-color: color-mix(in srgb, var(--ok) 50%, var(--line)); }
.fb.bad { border-color: color-mix(in srgb, var(--bad) 50%, var(--line)); }
.lesson-nav { display: flex; gap: 12px; justify-content: space-between; margin-top: 30px; padding-top: 22px; border-top: 1px solid var(--line); flex-wrap: wrap; }

/* ---------- command lab */
.lab { display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr); gap: 22px; align-items: start; }
@media (max-width: 1000px) { .lab { grid-template-columns: minmax(0, 1fr); } }
.editor { width: 100%; min-height: 190px; resize: vertical; background: transparent; border: 0; color: #e8ebff; font: 14px/1.7 'JetBrains Mono', monospace; padding: 16px 18px; outline: none; tab-size: 2; }
.editor::placeholder { color: #5e6590; }
.term-actions { display: flex; gap: 8px; padding: 12px 14px; border-top: 1px solid #22284a; background: #0d1022; flex-wrap: wrap; align-items: center; }
.term-actions .hint { color: #7c83ad; font-size: 12px; margin-left: auto; }
.term .seg { background: #11152b; border-color: #262c52; }
.term .seg button { color: #9aa1cc; }
.term .seg button[aria-pressed="true"] { background: #1f2550; color: #fff; box-shadow: inset 0 0 0 1px #343c74; }
.analysis { display: grid; gap: 14px; }
.risk { display: flex; gap: 14px; align-items: center; padding: 16px 18px; border-radius: 16px; border: 1px solid var(--line2); background: var(--surface); }
.risk .big { width: 46px; height: 46px; border-radius: 14px; display: grid; place-items: center; flex: none; }
.risk.read .big { background: color-mix(in srgb, var(--ok) 18%, var(--surface2)); color: var(--ok); }
.risk.change .big { background: color-mix(in srgb, var(--warn) 18%, var(--surface2)); color: var(--warn); }
.risk.danger .big { background: color-mix(in srgb, var(--bad) 18%, var(--surface2)); color: var(--bad); }
.risk.unknown .big { background: var(--surface3); color: var(--muted); }
.risk b { font-size: 16px; display: block; }
.risk small { color: var(--muted); }
.seg-list { display: grid; gap: 10px; }
.seg-item { padding: 14px 16px; border-radius: 14px; background: var(--surface); border: 1px solid var(--line); }
.seg-item header { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-bottom: 6px; }
.seg-item code.cmd { font-size: 14px; font-weight: 600; color: var(--text); background: none; border: 0; padding: 0; }
.seg-item p { margin: 0; color: var(--muted); font-size: 14px; }
.params { margin-top: 10px; display: grid; gap: 6px; }
.params div { display: grid; grid-template-columns: 150px 1fr; gap: 10px; font-size: 13px; color: var(--muted); }
.params code { justify-self: start; }
@media (max-width: 560px) { .params div { grid-template-columns: minmax(0, 1fr); gap: 2px; } }
.warnlist { display: grid; gap: 8px; }
.warnlist div { display: flex; gap: 10px; padding: 11px 13px; border-radius: 12px; font-size: 14px; border: 1px solid var(--line); background: var(--surface); }
.warnlist .w-bad { border-color: color-mix(in srgb, var(--bad) 45%, var(--line)); }
.warnlist .w-bad .ico { color: var(--bad); }
.warnlist .w-warn .ico { color: var(--warn); }
.warnlist .w-ok .ico { color: var(--ok); }
.warnlist .w-info .ico { color: var(--info); }
.sample { background: var(--code-bg); border: 1px dashed #343c74; border-radius: 14px; padding: 14px 16px; font: 12.5px/1.6 'JetBrains Mono', monospace; color: #c7cbef; white-space: pre; overflow-x: auto; }
.snips { display: flex; flex-wrap: wrap; gap: 8px; }
.snips button { background: var(--surface2); border: 1px solid var(--line); color: var(--text); border-radius: 10px; padding: 7px 11px; font: 550 13px 'Inter', sans-serif; cursor: pointer; }
.snips button:hover { border-color: var(--accent); }
.snips button.risky { border-color: color-mix(in srgb, var(--bad) 40%, var(--line)); }
.empty { text-align: center; padding: 34px 20px; color: var(--muted); border: 1px dashed var(--line2); border-radius: 16px; }
.empty .ico { margin: 0 auto 10px; color: var(--dim); width: 30px; height: 30px; }

/* ---------- reference tables */
.toolbar { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; margin-bottom: 16px; }
.input { background: var(--surface); border: 1px solid var(--line2); border-radius: 12px; color: var(--text); padding: 11px 14px; font: 14.5px 'Inter', sans-serif; width: 100%; }
.input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--glow); }
.toolbar .input { max-width: 340px; }
select.input { width: auto; }
textarea.input { min-height: 130px; resize: vertical; }
.cmd-card header { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; margin-bottom: 8px; }
.cmd-card header code { font-size: 14.5px; font-weight: 650; background: none; border: 0; padding: 0; color: var(--text); }
.cmd-card .syn { font: 12.5px 'JetBrains Mono', monospace; color: var(--dim); background: var(--surface2); border: 1px solid var(--line); padding: 8px 10px; border-radius: 9px; overflow-x: auto; white-space: nowrap; margin: 8px 0; }
.cmd-card .ex { font: 12.5px 'JetBrains Mono', monospace; color: var(--text); }
.cmd-card .row { margin-top: 10px; }
.gloss { display: grid; gap: 0; border: 1px solid var(--line); border-radius: 16px; overflow: hidden; }
.gloss div { display: grid; grid-template-columns: 220px 1fr; gap: 18px; padding: 13px 18px; border-top: 1px solid var(--line); background: var(--surface); }
.gloss div:first-child { border-top: 0; }
.gloss dt { font-weight: 700; }
.gloss dd { margin: 0; color: var(--muted); font-size: 14.5px; }
@media (max-width: 640px) { .gloss div { grid-template-columns: 1fr; gap: 4px; } }
.letters { display: flex; flex-wrap: wrap; gap: 4px; }
.letters a { width: 30px; height: 30px; display: grid; place-items: center; border-radius: 8px; color: var(--muted); font-weight: 650; font-size: 13px; background: var(--surface); border: 1px solid var(--line); }
.letters a:hover { color: var(--accent); text-decoration: none; }
.res-card .src { font: 600 11px 'JetBrains Mono', monospace; letter-spacing: .08em; color: var(--dim); text-transform: uppercase; }
.res-card a.go { display: inline-flex; gap: 6px; align-items: center; font-weight: 650; font-size: 14px; margin-top: 4px; }

/* ---------- exams */
.exam-shell { display: grid; grid-template-columns: minmax(0, 1fr) 260px; gap: 22px; align-items: start; }
@media (max-width: 960px) { .exam-shell { grid-template-columns: minmax(0, 1fr); } }
.qcard { padding: 26px; }
.qcard h2 { font-size: 21px; line-height: 1.4; font-weight: 650; }
.qnav { display: grid; grid-template-columns: repeat(8, 1fr); gap: 6px; }
.qnav button { aspect-ratio: 1; border-radius: 8px; border: 1px solid var(--line2); background: var(--surface); color: var(--muted); font: 600 11.5px 'JetBrains Mono', monospace; cursor: pointer; padding: 0; }
.qnav button.ans { background: var(--surface3); color: var(--text); }
.qnav button.flag { box-shadow: inset 0 -3px 0 var(--warn); }
.qnav button.cur { border-color: var(--accent); color: var(--accent); }
.qnav button.r { background: color-mix(in srgb, var(--ok) 22%, var(--surface)); color: var(--ok); }
.qnav button.x { background: color-mix(in srgb, var(--bad) 20%, var(--surface)); color: var(--bad); }
.timer { font: 700 26px 'JetBrains Mono', monospace; letter-spacing: .02em; }
.timer.low { color: var(--bad); }
.score-hero { display: flex; gap: 24px; align-items: center; flex-wrap: wrap; }
.score-big { font-size: 64px; font-weight: 850; letter-spacing: -.04em; line-height: 1; }
.breakdown { display: grid; gap: 10px; }
.breakdown div { display: grid; grid-template-columns: 1fr 120px 52px; gap: 12px; align-items: center; font-size: 14px; }
@media (max-width: 560px) { .breakdown div { grid-template-columns: 1fr 70px 44px; } }
.review-item { border-left: 3px solid var(--bad); }
.review-item.okq { border-left-color: var(--ok); }

/* ---------- guided labs */
.steps { counter-reset: st; display: grid; gap: 12px; }
.step { display: grid; grid-template-columns: 44px minmax(0, 1fr); gap: 14px; padding: 16px; background: var(--surface); border: 1px solid var(--line); border-radius: 16px; }
.step.done { border-color: color-mix(in srgb, var(--ok) 45%, var(--line)); }
.step-check { width: 36px; height: 36px; border-radius: 11px; border: 2px solid var(--line2); background: var(--surface2); cursor: pointer; display: grid; place-items: center; color: transparent; font: 700 13px 'JetBrains Mono', monospace; }
.step-check:hover { border-color: var(--accent); }
.step.done .step-check { background: var(--ok); border-color: var(--ok); color: #04150f; }
.step h3 { margin: 6px 0 4px; font-size: 16px; }
.step p { color: var(--muted); font-size: 14px; margin: 0; }
.step .codeblock { margin: 12px 0 0; }

/* ---------- progress */
.rank-card { display: grid; grid-template-columns: auto 1fr; gap: 22px; align-items: center; }
.rank-badge { width: 92px; height: 92px; border-radius: 26px; background: var(--grad); display: grid; place-items: center; color: var(--accent-ink); box-shadow: 0 10px 34px var(--glow); }
.rank-badge .ico { width: 42px; height: 42px; stroke-width: 1.6; }
.badges { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 12px; }
.badge { text-align: center; padding: 18px 12px; border-radius: 16px; background: var(--surface); border: 1px solid var(--line); }
.badge .tile-ico { margin: 0 auto 10px; }
.badge b { display: block; font-size: 13.5px; }
.badge small { color: var(--dim); font-size: 12px; }
.badge.locked { opacity: .45; filter: grayscale(1); }
.heat { display: grid; grid-template-columns: repeat(14, 1fr); gap: 5px; max-width: 420px; }
.heat i { aspect-ratio: 1; border-radius: 4px; background: var(--surface3); }
.heat i.on { background: var(--accent); box-shadow: 0 0 10px var(--glow); }
.mod-progress { display: grid; gap: 12px; }
.mod-progress a { display: grid; grid-template-columns: 1fr 160px 56px; gap: 14px; align-items: center; color: var(--text); font-size: 14px; }
.mod-progress a:hover { text-decoration: none; color: var(--accent); }
@media (max-width: 560px) { .mod-progress a { grid-template-columns: 1fr 80px 46px; } }
.table { width: 100%; border-collapse: collapse; font-size: 14px; }
.table th, .table td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); }
.table th { color: var(--dim); font-weight: 600; font-size: 12px; text-transform: uppercase; letter-spacing: .06em; }

/* ---------- prose pages */
.prose h2 { margin-top: 28px; }
.prose p, .prose li { color: var(--muted); }
.prose ul { padding-left: 20px; }
details.faq { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 0 18px; margin-bottom: 10px; }
details.faq summary { cursor: pointer; font-weight: 650; padding: 16px 0; list-style: none; display: flex; justify-content: space-between; gap: 10px; }
details.faq summary::-webkit-details-marker { display: none; }
details.faq summary::after { content: '+'; color: var(--accent); font-size: 20px; line-height: 1; }
details.faq[open] summary::after { content: '–'; }
details.faq p { color: var(--muted); padding-bottom: 16px; margin: 0; }
.field { display: grid; gap: 6px; margin-bottom: 14px; }
.field label { font-size: 13px; font-weight: 600; color: var(--muted); }
.brand-sheet img { width: 100%; height: auto; border-radius: 12px; }
.palette { display: flex; gap: 10px; flex-wrap: wrap; }
.palette div { width: 92px; }
.palette i { display: block; height: 56px; border-radius: 12px; border: 1px solid var(--line2); margin-bottom: 6px; }
.pal-1 { background: #b07aff; } .pal-2 { background: #7b8cff; } .pal-3 { background: #090a14; } .pal-4 { background: #3ee6d0; } .pal-5 { background: #b9f45f; }

/* ---------- search dialog & modal */
dialog { border: 1px solid var(--line2); background: var(--surface); color: var(--text); border-radius: 20px; padding: 0; box-shadow: var(--shadow); width: min(680px, calc(100vw - 24px)); }
dialog::backdrop { background: rgba(5, 6, 15, .62); backdrop-filter: blur(4px); }
.search-head { display: flex; gap: 10px; align-items: center; padding: 14px 16px; border-bottom: 1px solid var(--line); }
.search-head input { flex: 1; background: none; border: 0; color: var(--text); font: 17px 'Inter', sans-serif; outline: none; }
.search-results { max-height: min(60vh, 520px); overflow-y: auto; padding: 8px; }
.search-results .grp { font: 600 11px 'JetBrains Mono', monospace; letter-spacing: .12em; text-transform: uppercase; color: var(--dim); padding: 12px 10px 6px; }
.search-results a { display: flex; gap: 12px; align-items: center; padding: 10px; border-radius: 11px; color: var(--text); }
.search-results a small { display: block; color: var(--dim); font-size: 12.5px; }
.search-results a:hover, .search-results a.active { background: var(--surface2); text-decoration: none; }
.search-results a .ico { color: var(--accent); }
.search-foot { display: flex; gap: 14px; padding: 10px 16px; border-top: 1px solid var(--line); color: var(--dim); font-size: 12px; flex-wrap: wrap; }
.modal-body { padding: 24px; }
.modal-body h2 { font-size: 20px; }
.modal-actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 18px; }

/* ---------- toast, footer */
.toast { position: fixed; left: 50%; bottom: 26px; transform: translate(-50%, 20px); opacity: 0; pointer-events: none; z-index: 90; background: var(--surface3); border: 1px solid var(--line2); color: var(--text); padding: 11px 16px; border-radius: 12px; font-size: 14px; font-weight: 600; box-shadow: var(--shadow); transition: .25s; display: flex; gap: 10px; align-items: center; }
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.toast .ico { color: var(--accent); }
@media (max-width: 860px) { .toast { bottom: 92px; } }
.ftr { border-top: 1px solid var(--line); background: var(--bg2); margin-top: 30px; }
.ftr-in { max-width: 1240px; margin: 0 auto; padding: 38px 22px 28px; display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 26px; }
@media (max-width: 820px) { .ftr-in { grid-template-columns: 1fr 1fr; } }
.ftr h4 { font-size: 12px; text-transform: uppercase; letter-spacing: .12em; color: var(--dim); }
.ftr a { display: block; color: var(--muted); font-size: 14px; padding: 3px 0; }
.ftr img { height: 40px; width: auto; border-radius: 9px; margin-bottom: 12px; }
.ftr p { color: var(--dim); font-size: 13px; }
.legal-line { max-width: 1240px; margin: 0 auto; padding: 16px 22px 26px; border-top: 1px solid var(--line); color: var(--dim); font-size: 12.5px; display: flex; gap: 14px; justify-content: space-between; flex-wrap: wrap; }
@media (max-width: 860px) { .ftr { padding-bottom: 70px; } }

@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition: none !important; animation: none !important; scroll-behavior: auto !important; } }
@media print { .hdr, .tabbar, .ftr, .lesson-nav, .toc, .check { display: none !important; } body { background: #fff; color: #000; } .codeblock pre { color: #000; } }