:root {
  --bg: #f5f4ef;
  --bg-elevated: #fbfaf6;
  --surface: #ffffff;
  --surface-2: #efeee8;
  --surface-3: #e8e6df;
  --ink: #101426;
  --ink-soft: #515668;
  --ink-faint: #797d8c;
  --line: rgba(16, 20, 38, 0.12);
  --line-strong: rgba(16, 20, 38, 0.2);
  --accent: #715bff;
  --accent-2: #1daf96;
  --accent-3: #edaa32;
  --accent-soft: #ebe7ff;
  --accent-2-soft: #def7f1;
  --accent-3-soft: #fff0d0;
  --danger: #cf4c5c;
  --success: #168468;
  --shadow-sm: 0 1px 2px rgba(16,20,38,.04), 0 8px 20px rgba(16,20,38,.05);
  --shadow-md: 0 1px 2px rgba(16,20,38,.05), 0 18px 44px rgba(16,20,38,.10);
  --shadow-lg: 0 2px 4px rgba(16,20,38,.04), 0 28px 80px rgba(16,20,38,.15);
  --radius-sm: 10px;
  --radius-md: 18px;
  --radius-lg: 28px;
  --radius-xl: 38px;
  --shell: 1200px;
  --header-height: 72px;
}

html[data-theme="dark"] {
  --bg: #0d1020;
  --bg-elevated: #111526;
  --surface: #171b2e;
  --surface-2: #1f2439;
  --surface-3: #282e45;
  --ink: #f7f5ee;
  --ink-soft: #b6b9c7;
  --ink-faint: #8f93a5;
  --line: rgba(255,255,255,.10);
  --line-strong: rgba(255,255,255,.18);
  --accent: #9a88ff;
  --accent-2: #46d4bb;
  --accent-3: #f5bf5e;
  --accent-soft: rgba(113,91,255,.18);
  --accent-2-soft: rgba(29,175,150,.16);
  --accent-3-soft: rgba(237,170,50,.15);
  --danger: #ff7b8c;
  --success: #56d5b2;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.15), 0 8px 22px rgba(0,0,0,.18);
  --shadow-md: 0 1px 2px rgba(0,0,0,.18), 0 18px 44px rgba(0,0,0,.28);
  --shadow-lg: 0 2px 4px rgba(0,0,0,.2), 0 28px 80px rgba(0,0,0,.38);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  color: var(--ink);
  background:
    radial-gradient(circle at 15% 0%, rgba(113,91,255,.08), transparent 27rem),
    radial-gradient(circle at 90% 6%, rgba(29,175,150,.07), transparent 25rem),
    var(--bg);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
button, input, select, textarea { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; }
button { color: inherit; }
::selection { background: rgba(113,91,255,.25); }

.skip-link {
  position: fixed;
  z-index: 1000;
  top: 10px;
  left: 10px;
  transform: translateY(-140%);
  padding: 10px 14px;
  border-radius: 9px;
  color: white;
  background: var(--ink);
  transition: transform .2s ease;
}
.skip-link:focus { transform: translateY(0); }
.shell { width: min(calc(100% - 40px), var(--shell)); margin-inline: auto; }
.narrow-shell { width: min(calc(100% - 40px), 860px); margin-inline: auto; }

.site-header {
  position: sticky;
  z-index: 100;
  top: 0;
  height: var(--header-height);
  border-bottom: 1px solid transparent;
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(18px) saturate(1.2);
  transition: border-color .2s ease, box-shadow .2s ease, background .2s ease;
}
.site-header.is-scrolled { border-color: var(--line); box-shadow: 0 8px 28px rgba(16,20,38,.05); }
.header-inner { height: 100%; display: flex; align-items: center; justify-content: space-between; gap: 28px; }
.brand { display: inline-flex; align-items: center; gap: 11px; flex: none; }
.brand-mark { width: 38px; height: 38px; border-radius: 12px; background: var(--ink); position: relative; box-shadow: var(--shadow-sm); overflow: hidden; }
.brand-mark i { position: absolute; width: 9px; height: 9px; border-radius: 50%; }
.brand-mark i:nth-child(1) { left: 8px; top: 8px; background: var(--accent); }
.brand-mark i:nth-child(2) { right: 8px; top: 8px; background: var(--accent-2); }
.brand-mark i:nth-child(3) { left: 50%; bottom: 7px; transform: translateX(-50%); background: var(--accent-3); }
.brand-mark::before,
.brand-mark::after { content: ""; position: absolute; height: 1.5px; transform-origin: left center; background: rgba(255,255,255,.72); }
.brand-mark::before { width: 15px; left: 12px; top: 17px; transform: rotate(58deg); }
.brand-mark::after { width: 15px; right: 12px; top: 17px; transform: rotate(122deg); transform-origin: right center; }
.brand-copy { display: grid; line-height: 1.05; gap: 5px; }
.brand-copy strong { font-size: 15px; letter-spacing: -.02em; }
.brand-copy small { font-size: 10px; color: var(--ink-faint); letter-spacing: .08em; text-transform: uppercase; }
.desktop-nav { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.desktop-nav a { padding: 9px 12px; border-radius: 10px; color: var(--ink-soft); font-size: 14px; font-weight: 650; transition: .18s ease; }
.desktop-nav a:hover, .desktop-nav a.is-active { color: var(--ink); background: var(--surface); box-shadow: 0 1px 2px rgba(16,20,38,.04); }
.header-actions { display: flex; align-items: center; gap: 6px; }
.icon-button { width: 40px; height: 40px; padding: 0; display: grid; place-items: center; border: 1px solid var(--line); border-radius: 12px; color: var(--ink-soft); background: color-mix(in srgb, var(--surface) 75%, transparent); cursor: pointer; transition: .18s ease; }
.icon-button:hover { color: var(--ink); border-color: var(--line-strong); transform: translateY(-1px); }
.icon-button svg { width: 19px; height: 19px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; }
.theme-moon { display: none; }
html[data-theme="dark"] .theme-sun { display: none; }
html[data-theme="dark"] .theme-moon { display: block; }
.mobile-menu-button { display: none; width: 40px; height: 40px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface); padding: 10px 9px; cursor: pointer; }
.mobile-menu-button span { display: block; height: 1.5px; background: var(--ink); margin: 4px 0; transition: .2s ease; }
.mobile-nav { display: none; position: fixed; z-index: 99; inset: var(--header-height) 0 auto 0; padding: 12px 20px 20px; border-bottom: 1px solid var(--line); background: var(--bg-elevated); box-shadow: var(--shadow-md); }
.mobile-nav.is-open { display: grid; }
.mobile-nav a { padding: 12px 4px; border-bottom: 1px solid var(--line); font-weight: 700; }
.mobile-nav a:last-child { border: 0; }

main { min-height: 70vh; }
.page { animation: page-in .34s cubic-bezier(.2,.8,.2,1); }
@keyframes page-in { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }

.hero { padding: 76px 0 74px; position: relative; overflow: hidden; }
.hero::before { content: ""; position: absolute; width: 470px; height: 470px; border: 1px solid var(--line); border-radius: 50%; right: -180px; top: -210px; box-shadow: 0 0 0 70px rgba(113,91,255,.025), 0 0 0 140px rgba(29,175,150,.018); pointer-events: none; }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(420px, .95fr); align-items: center; gap: 76px; }
.eyebrow { display: inline-flex; align-items: center; gap: 8px; color: var(--accent); font-weight: 800; font-size: 12px; letter-spacing: .08em; text-transform: uppercase; }
.eyebrow::before { content: ""; width: 18px; height: 2px; border-radius: 4px; background: currentColor; }
.hero h1 { margin: 18px 0 22px; max-width: 720px; font-size: clamp(42px, 5.3vw, 76px); line-height: 1.02; letter-spacing: -.055em; font-weight: 850; }
.hero h1 .gradient-word { color: transparent; background: linear-gradient(120deg, var(--accent), #805dd8 45%, var(--accent-2)); -webkit-background-clip: text; background-clip: text; }
.hero-lead { max-width: 690px; margin: 0; color: var(--ink-soft); font-size: 19px; line-height: 1.7; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 11px; margin-top: 30px; }
.button { display: inline-flex; justify-content: center; align-items: center; gap: 9px; min-height: 44px; padding: 11px 17px; border: 1px solid transparent; border-radius: 12px; font-size: 14px; font-weight: 760; cursor: pointer; transition: .2s ease; }
.button svg { width: 17px; height: 17px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.button.primary { color: white; background: var(--ink); box-shadow: 0 8px 24px rgba(16,20,38,.15); }
html[data-theme="dark"] .button.primary { color: #111426; background: #f7f5ee; }
.button.primary:hover { transform: translateY(-2px); box-shadow: 0 14px 34px rgba(16,20,38,.22); }
.button.secondary { border-color: var(--line-strong); background: var(--surface); }
.button.secondary:hover { border-color: var(--accent); color: var(--accent); transform: translateY(-2px); }
.button.ghost { padding-inline: 4px; color: var(--accent); background: transparent; }
.button.ghost:hover { gap: 13px; }
.button.small { min-height: 36px; padding: 7px 12px; border-radius: 10px; font-size: 12px; }
.hero-proof { display: flex; align-items: center; flex-wrap: wrap; gap: 18px; margin-top: 30px; color: var(--ink-faint); font-size: 12px; }
.hero-proof span { display: inline-flex; align-items: center; gap: 7px; }
.hero-proof i { width: 7px; height: 7px; border-radius: 50%; background: var(--accent-2); box-shadow: 0 0 0 5px var(--accent-2-soft); }

.layer-map { position: relative; min-height: 510px; display: grid; place-items: center; }
.layer-map::before { content: ""; position: absolute; width: 380px; height: 380px; border-radius: 50%; background: radial-gradient(circle at 40% 35%, rgba(113,91,255,.20), rgba(29,175,150,.07) 45%, transparent 68%); filter: blur(6px); }
.layer-map-card { position: absolute; width: 270px; min-height: 80px; display: flex; align-items: center; gap: 14px; padding: 16px 18px; border: 1px solid rgba(255,255,255,.72); border-radius: 18px; background: color-mix(in srgb, var(--surface) 88%, transparent); box-shadow: var(--shadow-md); backdrop-filter: blur(16px); transition: transform .3s ease; }
html[data-theme="dark"] .layer-map-card { border-color: rgba(255,255,255,.10); }
.layer-map-card:hover { z-index: 3; transform: scale(1.035) rotate(0deg) !important; }
.layer-map-card:nth-child(1) { top: 6px; left: 16px; transform: rotate(-3deg); }
.layer-map-card:nth-child(2) { top: 100px; right: 2px; transform: rotate(3.5deg); }
.layer-map-card:nth-child(3) { top: 205px; left: 36px; transform: rotate(-1.2deg); }
.layer-map-card:nth-child(4) { top: 310px; right: 10px; transform: rotate(2deg); }
.layer-map-card:nth-child(5) { top: 411px; left: 18px; transform: rotate(-2deg); }
.layer-number { width: 42px; height: 42px; display: grid; place-items: center; flex: none; border-radius: 13px; color: var(--ink); background: var(--accent-soft); font-weight: 850; }
.layer-map-card:nth-child(2) .layer-number { background: var(--accent-2-soft); }
.layer-map-card:nth-child(3) .layer-number { background: var(--accent-3-soft); }
.layer-map-card:nth-child(4) .layer-number { background: #e4efff; }
html[data-theme="dark"] .layer-map-card:nth-child(4) .layer-number { background: rgba(72,135,255,.17); }
.layer-map-card:nth-child(5) .layer-number { color: white; background: var(--ink); }
.layer-map-card strong { display: block; font-size: 15px; }
.layer-map-card p { margin: 2px 0 0; color: var(--ink-faint); font-size: 12px; line-height: 1.45; }
.layer-arrow { position: absolute; z-index: 0; width: 2px; height: 350px; top: 72px; left: 50%; background: linear-gradient(transparent, var(--line-strong), transparent); }

.section { padding: 84px 0; }
.section.compact { padding: 58px 0; }
.section.tinted { background: color-mix(in srgb, var(--surface) 48%, transparent); border-block: 1px solid var(--line); }
.section.dark-panel { color: white; background: #101426; }
html[data-theme="dark"] .section.dark-panel { background: #080b16; }
.section-head { display: flex; align-items: end; justify-content: space-between; gap: 28px; margin-bottom: 34px; }
.section-head > div { max-width: 720px; }
.section-title { margin: 8px 0 8px; font-size: clamp(29px, 3.8vw, 46px); line-height: 1.12; letter-spacing: -.035em; }
.section-description { margin: 0; color: var(--ink-soft); font-size: 16px; }
.dark-panel .section-description { color: rgba(255,255,255,.66); }

.path-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.path-card { position: relative; min-height: 290px; display: flex; flex-direction: column; padding: 25px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow-sm); overflow: hidden; transition: .25s ease; }
.path-card:hover { transform: translateY(-5px); border-color: color-mix(in srgb, var(--card-accent, var(--accent)) 45%, var(--line)); box-shadow: var(--shadow-md); }
.path-card::after { content: ""; position: absolute; right: -46px; top: -50px; width: 150px; height: 150px; border-radius: 50%; background: color-mix(in srgb, var(--card-accent, var(--accent)) 11%, transparent); }
.path-icon { width: 46px; height: 46px; display: grid; place-items: center; border-radius: 14px; background: color-mix(in srgb, var(--card-accent, var(--accent)) 13%, transparent); color: var(--card-accent, var(--accent)); }
.path-icon svg { width: 23px; height: 23px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.path-card h3 { margin: 25px 0 8px; font-size: 22px; letter-spacing: -.025em; }
.path-card p { margin: 0 0 20px; color: var(--ink-soft); }
.path-steps { display: grid; gap: 7px; margin: auto 0 22px; padding: 0; list-style: none; color: var(--ink-faint); font-size: 13px; }
.path-steps li { display: flex; align-items: center; gap: 8px; }
.path-steps li::before { content: ""; width: 5px; height: 5px; border-radius: 50%; background: var(--card-accent, var(--accent)); }

.metric-strip { display: grid; grid-template-columns: repeat(4, 1fr); border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow-sm); overflow: hidden; }
.metric { padding: 25px 26px; border-right: 1px solid var(--line); }
.metric:last-child { border-right: 0; }
.metric strong { display: block; margin-bottom: 5px; font-size: 28px; line-height: 1; letter-spacing: -.04em; }
.metric span { color: var(--ink-faint); font-size: 12px; }

.product-ribbon { display: grid; grid-template-columns: repeat(5, 1fr); gap: 12px; }
.mini-product { display: flex; align-items: center; gap: 12px; min-width: 0; padding: 14px; border: 1px solid var(--line); border-radius: 15px; background: var(--surface); transition: .2s ease; }
.mini-product:hover { border-color: var(--product-color, var(--accent)); transform: translateY(-2px); box-shadow: var(--shadow-sm); }
.product-logo { width: 42px; height: 42px; display: grid; place-items: center; flex: none; border-radius: 13px; color: white; background: var(--product-color, var(--ink)); font-size: 12px; font-weight: 850; letter-spacing: -.02em; }
.mini-product strong { display: block; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; font-size: 13px; }
.mini-product span { display: block; color: var(--ink-faint); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; font-size: 11px; }

.concept-grid { display: grid; grid-template-columns: 1.05fr .95fr; gap: 20px; align-items: stretch; }
.concept-board { padding: 30px; border-radius: var(--radius-lg); color: white; background: #101426; overflow: hidden; position: relative; }
.concept-board::after { content: ""; position: absolute; right: -60px; bottom: -90px; width: 260px; height: 260px; border-radius: 50%; background: radial-gradient(circle, rgba(113,91,255,.42), transparent 68%); }
.concept-board h3 { margin: 0 0 8px; font-size: 28px; letter-spacing: -.035em; }
.concept-board > p { max-width: 600px; margin: 0; color: rgba(255,255,255,.65); }
.concept-flow { position: relative; z-index: 1; display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; margin-top: 36px; }
.concept-node { min-height: 130px; display: flex; flex-direction: column; justify-content: space-between; padding: 14px; border: 1px solid rgba(255,255,255,.13); border-radius: 15px; background: rgba(255,255,255,.055); }
.concept-node small { color: rgba(255,255,255,.42); font-size: 10px; letter-spacing: .1em; }
.concept-node strong { font-size: 15px; }
.concept-node span { color: rgba(255,255,255,.56); font-size: 11px; }
.concept-side { display: grid; gap: 15px; }
.insight-card { padding: 22px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.insight-card .icon-dot { width: 34px; height: 34px; display: grid; place-items: center; margin-bottom: 15px; border-radius: 11px; background: var(--accent-soft); color: var(--accent); font-weight: 850; }
.insight-card h4 { margin: 0 0 5px; font-size: 16px; }
.insight-card p { margin: 0; color: var(--ink-soft); font-size: 13px; }

.update-list { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.update-card { display: grid; grid-template-columns: auto 1fr auto; align-items: start; gap: 16px; padding: 20px; border: 1px solid rgba(255,255,255,.10); border-radius: 17px; background: rgba(255,255,255,.055); }
.update-date { display: grid; place-items: center; width: 50px; height: 50px; border-radius: 14px; color: #101426; background: var(--accent-2); font-size: 11px; line-height: 1.05; font-weight: 800; text-align: center; }
.update-card:nth-child(2n) .update-date { background: var(--accent-3); }
.update-card h4 { margin: 1px 0 5px; font-size: 15px; }
.update-card p { margin: 0; color: rgba(255,255,255,.59); font-size: 12px; }
.update-badge { padding: 5px 8px; border: 1px solid rgba(255,255,255,.13); border-radius: 999px; color: rgba(255,255,255,.66); font-size: 10px; }

.page-hero { padding: 64px 0 48px; border-bottom: 1px solid var(--line); }
.page-hero-grid { display: grid; grid-template-columns: 1fr auto; align-items: end; gap: 30px; }
.page-hero h1 { max-width: 800px; margin: 12px 0 12px; font-size: clamp(38px, 5vw, 64px); line-height: 1.03; letter-spacing: -.05em; }
.page-hero p { max-width: 760px; margin: 0; color: var(--ink-soft); font-size: 17px; }
.page-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 22px; }
.meta-chip, .tag { display: inline-flex; align-items: center; gap: 6px; padding: 6px 9px; border: 1px solid var(--line); border-radius: 999px; color: var(--ink-soft); background: var(--surface); font-size: 11px; font-weight: 650; }
.meta-chip i { width: 6px; height: 6px; border-radius: 50%; background: var(--accent-2); }

.progress-orb { width: 118px; height: 118px; position: relative; display: grid; place-items: center; border-radius: 50%; background: conic-gradient(var(--accent) var(--progress, 0%), var(--surface-3) 0); box-shadow: var(--shadow-sm); }
.progress-orb::before { content: ""; position: absolute; inset: 9px; border-radius: 50%; background: var(--bg); }
.progress-orb span { position: relative; z-index: 1; text-align: center; font-size: 11px; color: var(--ink-faint); line-height: 1.2; }
.progress-orb strong { display: block; color: var(--ink); font-size: 24px; }

.learn-layout { display: grid; grid-template-columns: 280px minmax(0, 1fr); gap: 34px; padding: 44px 0 92px; align-items: start; }
.lesson-sidebar { position: sticky; top: calc(var(--header-height) + 20px); }
.sidebar-card { padding: 18px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); box-shadow: var(--shadow-sm); }
.sidebar-card h2 { margin: 0 0 13px; font-size: 14px; }
.lesson-nav { display: grid; gap: 5px; }
.lesson-nav button { width: 100%; display: grid; grid-template-columns: 28px minmax(0, 1fr) 16px; align-items: center; gap: 9px; padding: 9px 8px; border: 0; border-radius: 10px; color: var(--ink-soft); background: transparent; text-align: left; cursor: pointer; transition: .18s ease; }
.lesson-nav button:hover, .lesson-nav button.is-active { color: var(--ink); background: var(--surface-2); }
.lesson-nav .lesson-index { width: 26px; height: 26px; display: grid; place-items: center; border-radius: 8px; background: var(--surface-2); color: var(--ink-faint); font-size: 10px; font-weight: 800; }
.lesson-nav button.is-active .lesson-index { color: white; background: var(--accent); }
.lesson-nav .lesson-title-mini { overflow: hidden; white-space: nowrap; text-overflow: ellipsis; font-size: 12px; font-weight: 700; }
.lesson-check { width: 15px; height: 15px; border: 1px solid var(--line-strong); border-radius: 50%; }
.lesson-check.done { display: grid; place-items: center; color: white; border-color: var(--success); background: var(--success); font-size: 9px; }
.sidebar-progress { margin-top: 15px; padding-top: 15px; border-top: 1px solid var(--line); }
.progress-line { height: 6px; border-radius: 99px; background: var(--surface-3); overflow: hidden; }
.progress-line i { display: block; height: 100%; width: var(--progress); border-radius: inherit; background: linear-gradient(90deg, var(--accent), var(--accent-2)); transition: width .35s ease; }
.sidebar-progress p { display: flex; justify-content: space-between; margin: 8px 0 0; color: var(--ink-faint); font-size: 11px; }

.lesson-article { min-width: 0; }
.lesson-header { padding: 32px 34px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow-sm); }
.lesson-kicker { display: flex; align-items: center; justify-content: space-between; gap: 12px; color: var(--ink-faint); font-size: 12px; font-weight: 700; }
.lesson-header h1 { margin: 16px 0 13px; font-size: clamp(32px, 4vw, 50px); line-height: 1.07; letter-spacing: -.045em; }
.lesson-header > p { max-width: 760px; margin: 0; color: var(--ink-soft); font-size: 17px; }
.lesson-objectives { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-top: 25px; }
.objective { padding: 13px; border-radius: 13px; background: var(--surface-2); }
.objective small { display: block; margin-bottom: 4px; color: var(--ink-faint); font-size: 9px; letter-spacing: .09em; text-transform: uppercase; }
.objective strong { font-size: 12px; line-height: 1.4; }
.lesson-body { margin-top: 18px; padding: 34px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); }
.lesson-body h2 { margin: 38px 0 12px; font-size: 25px; line-height: 1.22; letter-spacing: -.025em; }
.lesson-body h2:first-child { margin-top: 0; }
.lesson-body h3 { margin: 28px 0 8px; font-size: 18px; }
.lesson-body p { margin: 0 0 17px; color: var(--ink-soft); }
.lesson-body strong { color: var(--ink); }
.lesson-body ul, .lesson-body ol { color: var(--ink-soft); padding-left: 22px; }
.lesson-body li { margin: 7px 0; }
.lesson-body code { padding: 2px 6px; border-radius: 6px; background: var(--surface-2); color: var(--accent); font-size: .9em; }
.lesson-callout { margin: 24px 0; padding: 20px 21px; border-left: 4px solid var(--accent); border-radius: 0 15px 15px 0; background: var(--accent-soft); }
.lesson-callout.warning { border-left-color: var(--accent-3); background: var(--accent-3-soft); }
.lesson-callout.success { border-left-color: var(--accent-2); background: var(--accent-2-soft); }
.lesson-callout .callout-label { display: block; margin-bottom: 5px; color: var(--ink); font-size: 11px; font-weight: 850; letter-spacing: .06em; text-transform: uppercase; }
.lesson-callout p { margin: 0; color: var(--ink-soft); }
.lesson-diagram { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; margin: 24px 0; }
.diagram-item { min-height: 125px; display: flex; flex-direction: column; justify-content: space-between; padding: 14px; border: 1px solid var(--line); border-radius: 14px; background: var(--bg-elevated); }
.diagram-item b { width: 30px; height: 30px; display: grid; place-items: center; border-radius: 9px; color: white; background: var(--accent); font-size: 11px; }
.diagram-item:nth-child(2) b { background: var(--accent-2); }
.diagram-item:nth-child(3) b { color: var(--ink); background: var(--accent-3); }
.diagram-item:nth-child(4) b { background: #4e8eea; }
.diagram-item:nth-child(5) b { background: var(--ink); }
.diagram-item strong { font-size: 13px; }
.diagram-item span { color: var(--ink-faint); font-size: 10px; }
.lesson-compare { width: 100%; margin: 22px 0; border-collapse: collapse; font-size: 13px; }
.lesson-compare th, .lesson-compare td { padding: 12px 13px; border: 1px solid var(--line); text-align: left; vertical-align: top; }
.lesson-compare th { background: var(--surface-2); font-size: 11px; }
.lesson-compare td { color: var(--ink-soft); }
.lesson-footer { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 18px; padding: 18px 20px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.lesson-footer p { margin: 0; color: var(--ink-faint); font-size: 12px; }
.lesson-pagination { display: flex; gap: 8px; }

.product-toolbar { display: grid; grid-template-columns: minmax(260px, 1fr) auto; gap: 14px; margin: 32px 0 24px; }
.search-field { position: relative; }
.search-field svg { position: absolute; left: 15px; top: 50%; transform: translateY(-50%); width: 18px; height: 18px; fill: none; stroke: var(--ink-faint); stroke-width: 1.8; }
.search-field input { width: 100%; height: 48px; padding: 0 16px 0 44px; border: 1px solid var(--line); border-radius: 14px; color: var(--ink); background: var(--surface); outline: none; transition: .18s ease; }
.search-field input:focus { border-color: var(--accent); box-shadow: 0 0 0 4px var(--accent-soft); }
.filter-pills { display: flex; align-items: center; flex-wrap: wrap; gap: 7px; }
.filter-pill { height: 40px; padding: 0 13px; border: 1px solid var(--line); border-radius: 999px; color: var(--ink-soft); background: var(--surface); font-size: 12px; font-weight: 700; cursor: pointer; }
.filter-pill:hover, .filter-pill.is-active { color: white; border-color: var(--ink); background: var(--ink); }
html[data-theme="dark"] .filter-pill:hover, html[data-theme="dark"] .filter-pill.is-active { color: #101426; background: #f7f5ee; }
.product-count { margin: 0 0 14px; color: var(--ink-faint); font-size: 12px; }
.product-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; padding-bottom: 86px; }
.product-card { position: relative; min-height: 340px; display: flex; flex-direction: column; padding: 22px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow-sm); overflow: hidden; transition: .23s ease; }
.product-card:hover { transform: translateY(-4px); border-color: color-mix(in srgb, var(--product-color) 50%, var(--line)); box-shadow: var(--shadow-md); }
.product-card::after { content: ""; position: absolute; right: -50px; top: -60px; width: 170px; height: 170px; border-radius: 50%; background: color-mix(in srgb, var(--product-color) 10%, transparent); }
.product-card-top { display: flex; align-items: start; justify-content: space-between; gap: 12px; position: relative; z-index: 1; }
.product-card .product-logo { width: 50px; height: 50px; border-radius: 15px; font-size: 13px; }
.layer-label { padding: 5px 8px; border: 1px solid var(--line); border-radius: 999px; color: var(--ink-faint); background: color-mix(in srgb, var(--surface) 80%, transparent); font-size: 10px; }
.product-card h3 { position: relative; z-index: 1; margin: 20px 0 2px; font-size: 22px; line-height: 1.1; letter-spacing: -.03em; }
.product-company { position: relative; z-index: 1; color: var(--ink-faint); font-size: 11px; }
.product-tagline { position: relative; z-index: 1; margin: 16px 0; color: var(--ink-soft); font-size: 13px; }
.tag-row { position: relative; z-index: 1; display: flex; flex-wrap: wrap; gap: 6px; }
.tag { padding: 5px 8px; background: var(--surface-2); font-size: 10px; }
.product-card-bottom { position: relative; z-index: 1; display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: auto; padding-top: 20px; }
.cost-label { color: var(--ink-faint); font-size: 11px; }
.cost-dots { display: inline-flex; gap: 3px; margin-right: 5px; }
.cost-dots i { width: 5px; height: 5px; border-radius: 50%; background: var(--line-strong); }
.cost-dots i.on { background: var(--accent-3); }
.card-actions { display: flex; gap: 7px; }
.round-button { width: 35px; height: 35px; display: grid; place-items: center; border: 1px solid var(--line); border-radius: 11px; background: transparent; cursor: pointer; }
.round-button:hover { border-color: var(--accent); color: var(--accent); }
.round-button.is-selected { color: white; border-color: var(--accent); background: var(--accent); }
.round-button svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; }

.product-detail { padding-bottom: 90px; }
.product-detail-head { padding: 62px 0 42px; border-bottom: 1px solid var(--line); }
.product-detail-title { display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 22px; }
.product-detail-title .product-logo { width: 72px; height: 72px; border-radius: 21px; font-size: 17px; }
.product-detail-title h1 { margin: 0 0 5px; font-size: clamp(38px, 5vw, 62px); line-height: 1; letter-spacing: -.05em; }
.product-detail-title p { margin: 0; color: var(--ink-soft); }
.detail-grid { display: grid; grid-template-columns: minmax(0, 1fr) 310px; gap: 22px; padding-top: 26px; align-items: start; }
.detail-main { display: grid; gap: 16px; }
.detail-panel { padding: 26px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); }
.detail-panel h2 { margin: 0 0 15px; font-size: 20px; }
.detail-panel p { color: var(--ink-soft); }
.two-column-text { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.definition-card { padding: 18px; border-radius: var(--radius-md); background: var(--surface-2); }
.definition-card small { display: block; margin-bottom: 7px; color: var(--accent); font-size: 10px; font-weight: 850; letter-spacing: .08em; text-transform: uppercase; }
.definition-card p { margin: 0; font-size: 13px; }
.pro-con-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.pro-con { padding: 18px; border: 1px solid var(--line); border-radius: 15px; }
.pro-con.pro { background: var(--accent-2-soft); }
.pro-con.con { background: var(--accent-3-soft); }
.pro-con h3 { margin: 0 0 8px; font-size: 14px; }
.pro-con ul { margin: 0; padding-left: 18px; color: var(--ink-soft); font-size: 12px; }
.capability-list { display: grid; gap: 12px; }
.capability-row { display: grid; grid-template-columns: 100px 1fr 42px; align-items: center; gap: 12px; }
.capability-row span { color: var(--ink-soft); font-size: 12px; }
.capability-track { height: 7px; border-radius: 99px; background: var(--surface-3); overflow: hidden; }
.capability-track i { display: block; height: 100%; width: var(--value); border-radius: inherit; background: linear-gradient(90deg, var(--product-color), color-mix(in srgb, var(--product-color) 45%, var(--accent-2))); }
.capability-value { color: var(--ink-faint) !important; text-align: right; font-size: 10px !important; }
.detail-side { position: sticky; top: calc(var(--header-height) + 20px); display: grid; gap: 14px; }
.fact-card { padding: 20px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.fact-card h3 { margin: 0 0 14px; font-size: 14px; }
.fact-list { display: grid; gap: 11px; margin: 0; }
.fact-list div { display: grid; grid-template-columns: 84px 1fr; gap: 10px; padding-bottom: 9px; border-bottom: 1px solid var(--line); }
.fact-list div:last-child { border: 0; padding-bottom: 0; }
.fact-list dt { color: var(--ink-faint); font-size: 11px; }
.fact-list dd { margin: 0; font-size: 11px; font-weight: 700; text-align: right; }
.source-list { display: grid; gap: 7px; }
.source-link { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 10px 11px; border: 1px solid var(--line); border-radius: 10px; color: var(--ink-soft); font-size: 11px; transition: .18s ease; }
.source-link:hover { border-color: var(--accent); color: var(--accent); }
.source-link svg { width: 14px; height: 14px; fill: none; stroke: currentColor; stroke-width: 2; }

.compare-toolbar { display: grid; grid-template-columns: 1fr auto; gap: 18px; align-items: end; margin: 34px 0 22px; }
.compare-picker { display: flex; flex-wrap: wrap; gap: 8px; }
.compare-select { min-width: 210px; height: 46px; padding: 0 38px 0 13px; border: 1px solid var(--line); border-radius: 13px; color: var(--ink); background: var(--surface); outline: none; }
.compare-select:focus { border-color: var(--accent); }
.compare-selected { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 16px; }
.selected-chip { display: inline-flex; align-items: center; gap: 9px; padding: 7px 9px 7px 7px; border: 1px solid var(--line); border-radius: 999px; background: var(--surface); font-size: 11px; font-weight: 700; }
.selected-chip .product-logo { width: 27px; height: 27px; border-radius: 9px; font-size: 8px; }
.selected-chip button { border: 0; padding: 0; color: var(--ink-faint); background: none; cursor: pointer; font-size: 16px; }
.compare-wrap { overflow-x: auto; margin-bottom: 86px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); box-shadow: var(--shadow-sm); }
.compare-table { width: 100%; min-width: 760px; border-collapse: collapse; table-layout: fixed; }
.compare-table th, .compare-table td { padding: 15px 16px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); vertical-align: top; text-align: left; }
.compare-table tr:last-child td { border-bottom: 0; }
.compare-table th:last-child, .compare-table td:last-child { border-right: 0; }
.compare-table thead th { position: sticky; top: 0; z-index: 2; background: var(--surface); }
.compare-label { width: 180px; color: var(--ink-faint); background: var(--surface-2) !important; font-size: 11px; font-weight: 800; }
.compare-product-head { display: flex; align-items: center; gap: 12px; }
.compare-product-head .product-logo { width: 40px; height: 40px; border-radius: 12px; font-size: 10px; }
.compare-product-head strong { display: block; font-size: 14px; }
.compare-product-head span { display: block; color: var(--ink-faint); font-size: 10px; }
.compare-table td { color: var(--ink-soft); font-size: 12px; }
.level-pips { display: flex; gap: 4px; }
.level-pips i { width: 23px; height: 7px; border-radius: 99px; background: var(--surface-3); }
.level-pips i.on { background: var(--accent-2); }
.status-text { display: block; margin-top: 6px; color: var(--ink-faint); font-size: 10px; }
.empty-state { padding: 70px 24px; text-align: center; }
.empty-state-icon { width: 66px; height: 66px; display: grid; place-items: center; margin: 0 auto 18px; border-radius: 20px; color: var(--accent); background: var(--accent-soft); }
.empty-state-icon svg { width: 30px; height: 30px; fill: none; stroke: currentColor; stroke-width: 1.6; }
.empty-state h2 { margin: 0 0 8px; font-size: 22px; }
.empty-state p { max-width: 500px; margin: 0 auto 18px; color: var(--ink-soft); }

.pricing-intro-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 17px; margin: 34px 0 50px; }
.pricing-mode-card { position: relative; padding: 26px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); overflow: hidden; }
.pricing-mode-card::after { content: ""; position: absolute; width: 140px; height: 140px; right: -45px; top: -45px; border-radius: 50%; background: var(--accent-soft); }
.pricing-mode-card.api::after { background: var(--accent-2-soft); }
.pricing-mode-card h2 { position: relative; z-index: 1; margin: 0 0 8px; font-size: 25px; }
.pricing-mode-card > p { position: relative; z-index: 1; margin: 0 0 22px; color: var(--ink-soft); }
.mode-list { position: relative; z-index: 1; display: grid; gap: 9px; }
.mode-list div { display: grid; grid-template-columns: 85px 1fr; gap: 12px; padding: 10px 0; border-top: 1px solid var(--line); }
.mode-list dt { color: var(--ink-faint); font-size: 11px; }
.mode-list dd { margin: 0; font-size: 12px; font-weight: 650; }
.calculator-card { display: grid; grid-template-columns: .9fr 1.1fr; min-height: 480px; margin-bottom: 22px; border: 1px solid var(--line); border-radius: var(--radius-xl); background: var(--surface); box-shadow: var(--shadow-md); overflow: hidden; }
.calculator-inputs { padding: 32px; border-right: 1px solid var(--line); }
.calculator-inputs h2, .calculator-result h2 { margin: 0 0 6px; font-size: 24px; letter-spacing: -.03em; }
.calculator-inputs > p { margin: 0 0 25px; color: var(--ink-soft); font-size: 13px; }
.form-grid { display: grid; gap: 16px; }
.form-field { display: grid; gap: 7px; }
.form-field label { color: var(--ink-soft); font-size: 11px; font-weight: 700; }
.form-field input, .form-field select { width: 100%; height: 45px; padding: 0 12px; border: 1px solid var(--line); border-radius: 11px; color: var(--ink); background: var(--bg-elevated); outline: none; }
.form-field input:focus, .form-field select:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 11px; }
.range-row { display: grid; grid-template-columns: 1fr 48px; align-items: center; gap: 12px; }
.range-row input[type="range"] { height: auto; padding: 0; accent-color: var(--accent); }
.range-value { height: 34px; display: grid; place-items: center; border-radius: 9px; background: var(--surface-2); font-size: 11px; font-weight: 800; }
.calculator-result { position: relative; padding: 34px; color: white; background: #101426; overflow: hidden; }
.calculator-result::before { content: ""; position: absolute; width: 320px; height: 320px; right: -80px; top: -120px; border-radius: 50%; background: radial-gradient(circle, rgba(113,91,255,.56), transparent 68%); }
.calculator-result::after { content: ""; position: absolute; width: 250px; height: 250px; left: -100px; bottom: -150px; border-radius: 50%; background: radial-gradient(circle, rgba(29,175,150,.36), transparent 70%); }
.result-content { position: relative; z-index: 1; }
.calculator-result > .result-content > p { margin: 0; color: rgba(255,255,255,.58); font-size: 12px; }
.result-total { margin: 42px 0 8px; font-size: clamp(44px, 6vw, 72px); line-height: 1; letter-spacing: -.055em; font-weight: 850; }
.result-total small { margin-right: 5px; color: rgba(255,255,255,.58); font-size: .34em; letter-spacing: 0; }
.result-sub { color: rgba(255,255,255,.58); font-size: 12px; }
.cost-breakdown { display: grid; grid-template-columns: repeat(3, 1fr); gap: 9px; margin-top: 32px; }
.cost-box { padding: 13px; border: 1px solid rgba(255,255,255,.12); border-radius: 13px; background: rgba(255,255,255,.055); }
.cost-box small { display: block; margin-bottom: 4px; color: rgba(255,255,255,.48); font-size: 9px; }
.cost-box strong { font-size: 15px; }
.calc-note { margin-top: 26px; padding: 13px 14px; border-radius: 12px; color: rgba(255,255,255,.64); background: rgba(255,255,255,.07); font-size: 10px; }
.cost-factors { display: grid; grid-template-columns: repeat(4, 1fr); gap: 13px; margin: 30px 0 86px; }
.factor-card { padding: 20px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.factor-card b { display: grid; place-items: center; width: 32px; height: 32px; margin-bottom: 14px; border-radius: 10px; color: var(--accent); background: var(--accent-soft); }
.factor-card h3 { margin: 0 0 6px; font-size: 14px; }
.factor-card p { margin: 0; color: var(--ink-soft); font-size: 11px; }

.glossary-layout { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 28px; padding: 35px 0 86px; align-items: start; }
.glossary-filter { position: sticky; top: calc(var(--header-height) + 20px); }
.glossary-filter h2 { margin: 0 0 12px; font-size: 13px; }
.glossary-filter-list { display: grid; gap: 5px; }
.glossary-filter-list button { display: flex; justify-content: space-between; width: 100%; padding: 9px 11px; border: 0; border-radius: 9px; color: var(--ink-soft); background: transparent; text-align: left; cursor: pointer; font-size: 11px; }
.glossary-filter-list button:hover, .glossary-filter-list button.is-active { color: var(--ink); background: var(--surface-2); }
.glossary-filter-list span { color: var(--ink-faint); }
.glossary-main .search-field { margin-bottom: 16px; }
.glossary-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.term-card { padding: 20px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); transition: .2s ease; }
.term-card:hover { transform: translateY(-2px); border-color: var(--accent); box-shadow: var(--shadow-sm); }
.term-head { display: flex; align-items: start; justify-content: space-between; gap: 10px; }
.term-head h3 { margin: 0; font-size: 17px; }
.term-en { display: block; margin-top: 1px; color: var(--ink-faint); font-size: 10px; }
.term-category { padding: 4px 7px; border-radius: 999px; color: var(--accent); background: var(--accent-soft); font-size: 9px; font-weight: 750; }
.term-card p { margin: 13px 0 0; color: var(--ink-soft); font-size: 12px; }
.term-example { margin-top: 12px; padding-top: 10px; border-top: 1px solid var(--line); color: var(--ink-faint); font-size: 10px; }

.quiz-wrap { padding: 45px 0 90px; }
.quiz-card { max-width: 820px; margin: 0 auto; padding: 34px; border: 1px solid var(--line); border-radius: var(--radius-xl); background: var(--surface); box-shadow: var(--shadow-md); }
.quiz-progress { display: flex; justify-content: space-between; margin-bottom: 14px; color: var(--ink-faint); font-size: 11px; }
.quiz-progress-line { height: 7px; margin-bottom: 30px; border-radius: 99px; background: var(--surface-3); overflow: hidden; }
.quiz-progress-line i { display: block; height: 100%; width: var(--progress); border-radius: inherit; background: linear-gradient(90deg, var(--accent), var(--accent-2)); transition: width .3s ease; }
.quiz-question { margin: 0 0 22px; font-size: clamp(23px, 3vw, 31px); line-height: 1.25; letter-spacing: -.025em; }
.quiz-options { display: grid; gap: 10px; }
.quiz-option { display: grid; grid-template-columns: 34px 1fr; align-items: center; gap: 12px; padding: 14px; border: 1px solid var(--line); border-radius: 14px; color: var(--ink-soft); background: var(--bg-elevated); text-align: left; cursor: pointer; transition: .18s ease; }
.quiz-option:hover { border-color: var(--accent); transform: translateX(3px); }
.quiz-option.is-selected { color: var(--ink); border-color: var(--accent); background: var(--accent-soft); }
.quiz-option.is-correct { color: var(--ink); border-color: var(--success); background: var(--accent-2-soft); }
.quiz-option.is-wrong { border-color: var(--danger); background: color-mix(in srgb, var(--danger) 10%, var(--surface)); }
.option-letter { width: 32px; height: 32px; display: grid; place-items: center; border-radius: 10px; background: var(--surface-2); font-size: 11px; font-weight: 850; }
.quiz-feedback { margin-top: 18px; padding: 15px; border-radius: 13px; background: var(--surface-2); color: var(--ink-soft); font-size: 12px; }
.quiz-actions { display: flex; justify-content: space-between; gap: 10px; margin-top: 24px; }
.quiz-result { text-align: center; }
.score-ring { width: 148px; height: 148px; display: grid; place-items: center; margin: 0 auto 26px; border-radius: 50%; background: conic-gradient(var(--accent-2) var(--score), var(--surface-3) 0); }
.score-ring::before { content: ""; grid-area: 1/1; width: 118px; height: 118px; border-radius: 50%; background: var(--surface); }
.score-ring strong { grid-area: 1/1; position: relative; z-index: 1; font-size: 35px; line-height: 1; }
.score-ring small { display: block; font-size: 10px; color: var(--ink-faint); }
.quiz-result h2 { margin: 0 0 8px; font-size: 30px; }
.quiz-result p { color: var(--ink-soft); }
.result-actions { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-top: 24px; }

.info-page { padding: 46px 0 90px; }
.info-layout { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 32px; align-items: start; }
.info-toc { position: sticky; top: calc(var(--header-height) + 20px); padding: 16px; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.info-toc h3 { margin: 0 0 10px; font-size: 12px; }
.info-toc a { display: block; padding: 7px 0; color: var(--ink-soft); font-size: 11px; }
.info-toc a:hover { color: var(--accent); }
.prose { padding: 30px 34px; border: 1px solid var(--line); border-radius: var(--radius-lg); background: var(--surface); }
.prose h2 { margin: 40px 0 12px; font-size: 25px; letter-spacing: -.025em; }
.prose h2:first-child { margin-top: 0; }
.prose h3 { margin: 26px 0 8px; font-size: 17px; }
.prose p, .prose li { color: var(--ink-soft); }
.prose li { margin: 6px 0; }
.method-scale { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin: 18px 0; }
.scale-card { padding: 16px; border-radius: 13px; background: var(--surface-2); }
.scale-card b { display: block; margin-bottom: 5px; font-size: 18px; }
.scale-card span { color: var(--ink-soft); font-size: 10px; }
.source-index { display: grid; gap: 10px; }
.source-index-item { display: grid; grid-template-columns: 48px minmax(0, 1fr) auto; align-items: center; gap: 14px; padding: 14px; border: 1px solid var(--line); border-radius: 13px; }
.source-index-item .product-logo { width: 42px; height: 42px; border-radius: 12px; font-size: 9px; }
.source-index-item strong { display: block; font-size: 13px; }
.source-index-item span { display: block; color: var(--ink-faint); font-size: 10px; }
.changelog { display: grid; gap: 0; }
.change-item { display: grid; grid-template-columns: 105px 16px 1fr; gap: 16px; }
.change-date { padding-top: 4px; color: var(--ink-faint); font-size: 11px; text-align: right; }
.change-line { position: relative; }
.change-line::before { content: ""; position: absolute; left: 7px; top: 7px; bottom: -8px; width: 1px; background: var(--line-strong); }
.change-item:last-child .change-line::before { display: none; }
.change-line::after { content: ""; position: absolute; left: 3px; top: 5px; width: 9px; height: 9px; border: 2px solid var(--surface); border-radius: 50%; background: var(--accent); box-shadow: 0 0 0 1px var(--accent); }
.change-content { padding: 0 0 28px; }
.change-content h3 { margin: 0 0 5px; font-size: 14px; }
.change-content p { margin: 0; color: var(--ink-soft); font-size: 11px; }

.search-dialog { width: min(680px, calc(100% - 28px)); max-height: min(78vh, 720px); padding: 0; border: 1px solid var(--line); border-radius: 24px; color: var(--ink); background: var(--surface); box-shadow: var(--shadow-lg); overflow: hidden; }
.search-dialog::backdrop { background: rgba(8,11,22,.56); backdrop-filter: blur(5px); }
.search-dialog-head { display: flex; align-items: center; justify-content: space-between; padding: 22px 23px 15px; }
.search-dialog-head h2 { margin: 3px 0 0; font-size: 23px; letter-spacing: -.03em; }
.search-input-wrap { position: relative; display: block; margin: 0 22px 16px; }
.search-input-wrap > svg { position: absolute; left: 14px; top: 50%; transform: translateY(-50%); width: 19px; height: 19px; fill: none; stroke: var(--ink-faint); stroke-width: 1.8; }
.search-input-wrap input { width: 100%; height: 51px; padding: 0 62px 0 44px; border: 1px solid var(--line); border-radius: 14px; color: var(--ink); background: var(--bg-elevated); outline: none; }
.search-input-wrap input:focus { border-color: var(--accent); box-shadow: 0 0 0 4px var(--accent-soft); }
kbd { position: absolute; right: 11px; top: 50%; transform: translateY(-50%); padding: 3px 6px; border: 1px solid var(--line); border-radius: 6px; color: var(--ink-faint); background: var(--surface); font-size: 9px; font-family: inherit; }
.search-results { max-height: 490px; padding: 0 22px 22px; overflow-y: auto; }
.search-result-group h3 { margin: 15px 0 7px; color: var(--ink-faint); font-size: 10px; letter-spacing: .08em; text-transform: uppercase; }
.search-result { display: grid; grid-template-columns: 35px minmax(0,1fr) auto; align-items: center; gap: 11px; padding: 10px; border-radius: 11px; cursor: pointer; }
.search-result:hover { background: var(--surface-2); }
.search-result-icon { width: 34px; height: 34px; display: grid; place-items: center; border-radius: 10px; color: var(--accent); background: var(--accent-soft); font-size: 10px; font-weight: 850; }
.search-result strong { display: block; font-size: 12px; }
.search-result span { display: block; color: var(--ink-faint); font-size: 10px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.search-result em { color: var(--ink-faint); font-size: 10px; font-style: normal; }

.toast-region { position: fixed; z-index: 500; right: 18px; bottom: 18px; display: grid; gap: 8px; pointer-events: none; }
.toast { max-width: 330px; padding: 12px 15px; border: 1px solid var(--line); border-radius: 12px; color: var(--ink); background: var(--surface); box-shadow: var(--shadow-md); font-size: 11px; animation: toast-in .25s ease, toast-out .25s ease 2.75s forwards; }
@keyframes toast-in { from { opacity: 0; transform: translateY(12px); } }
@keyframes toast-out { to { opacity: 0; transform: translateY(10px); } }

.site-footer { padding: 58px 0 20px; border-top: 1px solid var(--line); background: var(--bg-elevated); }
.footer-grid { display: grid; grid-template-columns: 1.6fr repeat(3, .7fr); gap: 46px; }
.footer-brand { margin-bottom: 16px; }
.footer-grid > div:first-child p { max-width: 440px; margin: 0; color: var(--ink-soft); font-size: 12px; }
.footer-grid h3 { margin: 0 0 12px; font-size: 12px; }
.footer-grid > div:not(:first-child) a { display: block; margin: 7px 0; color: var(--ink-soft); font-size: 11px; }
.footer-grid a:hover { color: var(--accent); }
.footer-bottom { display: flex; justify-content: space-between; gap: 20px; margin-top: 42px; padding-top: 16px; border-top: 1px solid var(--line); color: var(--ink-faint); font-size: 10px; }

@media (max-width: 1050px) {
  .desktop-nav { display: none; }
  .mobile-menu-button { display: block; }
  .hero-grid { grid-template-columns: 1fr 420px; gap: 34px; }
  .product-ribbon { grid-template-columns: repeat(3, 1fr); }
  .product-grid { grid-template-columns: repeat(2, 1fr); }
  .concept-flow { grid-template-columns: repeat(3, 1fr); }
  .cost-factors { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 860px) {
  .hero { padding-top: 55px; }
  .hero-grid { grid-template-columns: 1fr; }
  .layer-map { min-height: 500px; max-width: 500px; width: 100%; margin: 10px auto 0; }
  .path-grid { grid-template-columns: 1fr; }
  .path-card { min-height: 250px; }
  .metric-strip { grid-template-columns: 1fr 1fr; }
  .metric:nth-child(2) { border-right: 0; }
  .metric:nth-child(-n+2) { border-bottom: 1px solid var(--line); }
  .concept-grid { grid-template-columns: 1fr; }
  .update-list { grid-template-columns: 1fr; }
  .page-hero-grid { grid-template-columns: 1fr; }
  .progress-orb { display: none; }
  .learn-layout { grid-template-columns: 1fr; }
  .lesson-sidebar { position: static; }
  .lesson-nav { grid-template-columns: repeat(4, 1fr); }
  .lesson-nav button { grid-template-columns: 28px 1fr; }
  .lesson-check { display: none; }
  .product-toolbar { grid-template-columns: 1fr; }
  .detail-grid { grid-template-columns: 1fr; }
  .detail-side { position: static; grid-template-columns: 1fr 1fr; }
  .calculator-card { grid-template-columns: 1fr; }
  .calculator-inputs { border-right: 0; border-bottom: 1px solid var(--line); }
  .glossary-layout, .info-layout { grid-template-columns: 1fr; }
  .glossary-filter, .info-toc { position: static; }
  .glossary-filter-list { display: flex; flex-wrap: wrap; }
  .glossary-filter-list button { width: auto; gap: 8px; }
  .footer-grid { grid-template-columns: 1.4fr 1fr 1fr; }
  .footer-grid > div:nth-child(4) { display: none; }
}

@media (max-width: 640px) {
  :root { --header-height: 64px; }
  .shell, .narrow-shell { width: min(calc(100% - 28px), var(--shell)); }
  .site-header { height: var(--header-height); }
  .brand-copy small { display: none; }
  .header-actions .icon-button:first-child { display: none; }
  .hero { padding: 43px 0 46px; }
  .hero h1 { font-size: 44px; }
  .hero-lead { font-size: 16px; }
  .hero-actions .button { flex: 1 1 auto; }
  .hero-proof { gap: 11px; }
  .layer-map { min-height: 445px; }
  .layer-map-card { width: 232px; min-height: 70px; padding: 12px; }
  .layer-map-card:nth-child(1) { left: 0; }
  .layer-map-card:nth-child(2) { right: 0; top: 85px; }
  .layer-map-card:nth-child(3) { left: 10px; top: 175px; }
  .layer-map-card:nth-child(4) { right: 0; top: 270px; }
  .layer-map-card:nth-child(5) { left: 0; top: 365px; }
  .layer-number { width: 36px; height: 36px; }
  .section { padding: 60px 0; }
  .section-head { display: block; }
  .section-head .button { margin-top: 16px; }
  .metric-strip { border-radius: 18px; }
  .metric { padding: 20px; }
  .product-ribbon { grid-template-columns: 1fr 1fr; }
  .concept-board { padding: 23px; }
  .concept-flow { grid-template-columns: 1fr 1fr; }
  .concept-node { min-height: 112px; }
  .page-hero { padding: 45px 0 34px; }
  .page-hero h1 { font-size: 42px; }
  .lesson-nav { grid-template-columns: 1fr 1fr; }
  .lesson-header, .lesson-body { padding: 23px; }
  .lesson-objectives { grid-template-columns: 1fr; }
  .lesson-diagram { grid-template-columns: 1fr 1fr; }
  .lesson-footer { align-items: flex-start; flex-direction: column; }
  .product-grid { grid-template-columns: 1fr; }
  .product-card { min-height: 310px; }
  .product-detail-title { grid-template-columns: auto 1fr; }
  .product-detail-title > .button { grid-column: 1 / -1; }
  .two-column-text, .pro-con-grid, .detail-side { grid-template-columns: 1fr; }
  .compare-toolbar { grid-template-columns: 1fr; }
  .compare-select { width: 100%; }
  .pricing-intro-grid { grid-template-columns: 1fr; }
  .calculator-inputs, .calculator-result { padding: 23px; }
  .field-row { grid-template-columns: 1fr; }
  .cost-breakdown { grid-template-columns: 1fr; }
  .cost-factors { grid-template-columns: 1fr; }
  .glossary-grid { grid-template-columns: 1fr; }
  .quiz-card { padding: 23px; border-radius: 24px; }
  .info-page { padding-top: 28px; }
  .prose { padding: 23px; }
  .method-scale { grid-template-columns: 1fr 1fr; }
  .source-index-item { grid-template-columns: 42px minmax(0,1fr); }
  .source-index-item .button { grid-column: 1 / -1; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 30px; }
  .footer-grid > div:first-child { grid-column: 1 / -1; }
  .footer-bottom { flex-direction: column; }
  .toast-region { left: 14px; right: 14px; }
  .toast { max-width: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; transition-duration: .01ms !important; }
}