/* ============================================================
   shared.css — Figma MCP & Pencil.dev 知識庫
   shadcn/ui (new-york · neutral) 設計語言 · OKLCH 雙模式
   單一真相源：DESIGN.md。本檔只定義 token 與元件，禁 hardcode。
   ============================================================ */

/* ---------- §1 Tokens — :root (light) ---------- */
:root {
  /* base palette (OKLCH, chroma 0 = neutral) */
  --background: oklch(1 0 0);
  --foreground: oklch(0.145 0 0);
  --card: oklch(1 0 0);
  --card-foreground: oklch(0.145 0 0);
  --popover: oklch(1 0 0);
  --popover-foreground: oklch(0.145 0 0);
  --primary: oklch(0.205 0 0);
  --primary-foreground: oklch(0.985 0 0);
  --secondary: oklch(0.97 0 0);
  --secondary-foreground: oklch(0.205 0 0);
  --muted: oklch(0.97 0 0);
  --muted-foreground: oklch(0.556 0 0);
  --accent: oklch(0.97 0 0);
  --accent-foreground: oklch(0.205 0 0);
  --destructive: oklch(0.577 0.245 27.3);
  --border: oklch(0.922 0 0);
  --input: oklch(0.922 0 0);
  --ring: oklch(0.439 0 0);
  /* semantic colour roles */
  --success: oklch(0.527 0.118 152);
  --warning: oklch(0.553 0.135 66);
  --info: oklch(0.546 0.215 263);
  /* sidebar scope */
  --sidebar: oklch(0.985 0 0);
  --sidebar-foreground: oklch(0.145 0 0);
  --sidebar-primary: oklch(0.205 0 0);
  --sidebar-primary-foreground: oklch(0.985 0 0);
  --sidebar-accent: oklch(0.97 0 0);
  --sidebar-accent-foreground: oklch(0.205 0 0);
  --sidebar-border: oklch(0.922 0 0);
  --sidebar-ring: oklch(0.439 0 0);

  /* derived */
  --destructive-foreground: oklch(0.985 0 0);
  --success-bg: color-mix(in oklab, var(--success) 12%, transparent);
  --success-border: color-mix(in oklab, var(--success) 36%, transparent);
  --warning-bg: color-mix(in oklab, var(--warning) 12%, transparent);
  --warning-border: color-mix(in oklab, var(--warning) 36%, transparent);
  --info-bg: color-mix(in oklab, var(--info) 12%, transparent);
  --info-border: color-mix(in oklab, var(--info) 36%, transparent);
  --destructive-bg: color-mix(in oklab, var(--destructive) 10%, transparent);
  --destructive-border: color-mix(in oklab, var(--destructive) 34%, transparent);
  /* semantic badge text — darkened vs base for AA on 12% tint (.dark aliases base) */
  --info-text: oklch(0.527 0.215 263);
  --warning-text: oklch(0.525 0.135 66);
  --success-text: oklch(0.505 0.118 152);
  --destructive-text: oklch(0.515 0.245 27.3);
  --code-bg: var(--muted);
  --code-foreground: var(--foreground);
  --overlay: color-mix(in oklab, var(--foreground) 45%, transparent);
  --zebra: color-mix(in oklab, var(--muted) 50%, transparent);

  /* radius */
  --radius: 0.625rem;
  --radius-sm: calc(var(--radius) - 4px);
  --radius-md: calc(var(--radius) - 2px);
  --radius-lg: var(--radius);
  --radius-xl: calc(var(--radius) + 4px);
  --radius-full: 9999px;

  /* layout */
  --sidebar-width: 260px;
  --topbar-height: 61px;

  /* spacing (4px scale) */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;

  /* shadow */
  --shadow-xs: 0 1px 2px 0 color-mix(in oklab, var(--foreground) 5%, transparent);
  --shadow-sm: 0 1px 3px 0 color-mix(in oklab, var(--foreground) 8%, transparent), 0 1px 2px -1px color-mix(in oklab, var(--foreground) 8%, transparent);
  --shadow-md: 0 4px 6px -1px color-mix(in oklab, var(--foreground) 8%, transparent), 0 2px 4px -2px color-mix(in oklab, var(--foreground) 8%, transparent);
  --shadow-lg: 0 10px 15px -3px color-mix(in oklab, var(--foreground) 10%, transparent), 0 4px 6px -4px color-mix(in oklab, var(--foreground) 8%, transparent);

  /* fonts */
  --font-sans: 'Inter', 'Noto Sans TC', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', ui-monospace, monospace;

  /* §4 motion */
  --duration-fast: 150ms;
  --duration-normal: 250ms;
  --duration-slow: 400ms;
  --duration-theme: 300ms;
  --duration-enter: 500ms;
  --ease-default: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-out: cubic-bezier(0, 0, 0.2, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);

  color-scheme: light;
}

/* ---------- §1 Tokens — .dark ---------- */
.dark {
  --background: oklch(0.145 0 0);
  --foreground: oklch(0.985 0 0);
  --card: oklch(0.205 0 0);
  --card-foreground: oklch(0.985 0 0);
  --popover: oklch(0.205 0 0);
  --popover-foreground: oklch(0.985 0 0);
  --primary: oklch(0.922 0 0);
  --primary-foreground: oklch(0.205 0 0);
  --secondary: oklch(0.269 0 0);
  --secondary-foreground: oklch(0.985 0 0);
  --muted: oklch(0.269 0 0);
  --muted-foreground: oklch(0.708 0 0);
  --accent: oklch(0.269 0 0);
  --accent-foreground: oklch(0.985 0 0);
  --destructive: oklch(0.704 0.191 22.2);
  --border: oklch(1 0 0 / 0.10);
  --input: oklch(1 0 0 / 0.15);
  --ring: oklch(0.708 0 0);
  --success: oklch(0.792 0.209 152);
  --warning: oklch(0.852 0.166 86);
  --info: oklch(0.712 0.143 254);
  --sidebar: oklch(0.205 0 0);
  --sidebar-foreground: oklch(0.985 0 0);
  --sidebar-primary: oklch(0.922 0 0);
  --sidebar-primary-foreground: oklch(0.205 0 0);
  --sidebar-accent: oklch(0.269 0 0);
  --sidebar-accent-foreground: oklch(0.985 0 0);
  --sidebar-border: oklch(1 0 0 / 0.10);
  --sidebar-ring: oklch(0.708 0 0);
  --destructive-foreground: oklch(0.205 0 0);
  --info-text: var(--info);
  --warning-text: var(--warning);
  --success-text: var(--success);
  --destructive-text: var(--destructive);

  color-scheme: dark;
}

/* ---------- Reset & base ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--topbar-height) + var(--space-5));
}

body {
  font-family: var(--font-sans);
  background: var(--background);
  color: var(--foreground);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* global theme transition */
*, *::before, *::after {
  transition: background-color var(--duration-theme) var(--ease-default),
              color var(--duration-theme) var(--ease-default),
              border-color var(--duration-theme) var(--ease-default),
              box-shadow var(--duration-theme) var(--ease-default);
}

/* scrollbar */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: color-mix(in oklab, var(--foreground) 18%, transparent);
  border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover {
  background: color-mix(in oklab, var(--foreground) 30%, transparent);
}

/* custom element wrappers are layout-transparent */
kb-sidebar, kb-topbar { display: contents; }

/* ---------- Utilities ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}
.skip-link:focus {
  position: fixed;
  top: var(--space-3);
  left: var(--space-3);
  z-index: 10000;
  width: auto;
  height: auto;
  margin: 0;
  padding: var(--space-3) var(--space-6);
  overflow: visible;
  clip: auto;
  background: var(--primary);
  color: var(--primary-foreground);
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius-md);
  text-decoration: none;
}

/* shared focus-visible ring */
:where(a, button, input, [tabindex]):focus-visible {
  outline: 2px solid var(--ring);
  outline-offset: 2px;
}

/* ---------- §2 Button ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  height: 36px;
  padding: 0 var(--space-4);
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 600;
  line-height: 1;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--foreground);
  cursor: pointer;
  white-space: nowrap;
  transition: background-color var(--duration-fast) var(--ease-default),
              border-color var(--duration-fast) var(--ease-default),
              color var(--duration-fast) var(--ease-default),
              transform var(--duration-fast) var(--ease-default);
}
.btn:active { transform: scale(0.98); }
.btn:disabled { opacity: 0.5; pointer-events: none; }

.btn-sm { height: 32px; padding: 0 var(--space-3); font-size: 13px; }
.btn-lg { height: 40px; padding: 0 var(--space-6); }
.btn-icon { width: 36px; height: 36px; padding: 0; }

.btn-default { background: var(--primary); color: var(--primary-foreground); border-color: var(--primary); }
.btn-default:hover { background: color-mix(in oklab, var(--primary) 90%, transparent); }

.btn-secondary { background: var(--secondary); color: var(--secondary-foreground); border-color: var(--secondary); }
.btn-secondary:hover { background: color-mix(in oklab, var(--secondary) 80%, transparent); }

.btn-outline { background: var(--background); color: var(--foreground); border-color: var(--border); }
.btn-outline:hover { background: var(--accent); color: var(--accent-foreground); }

.btn-ghost { background: transparent; color: var(--foreground); }
.btn-ghost:hover { background: var(--accent); color: var(--accent-foreground); }

.btn-destructive { background: var(--destructive); color: var(--destructive-foreground); border-color: var(--destructive); }
.btn-destructive:hover { background: color-mix(in oklab, var(--destructive) 90%, transparent); }

.btn-link { background: transparent; color: var(--primary); height: auto; padding: 0; }
.btn-link:hover { text-decoration: underline; text-underline-offset: 4px; }

/* ---------- Layout: sidebar / main / topbar ---------- */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  height: 100dvh;
  background: var(--sidebar);
  border-right: 1px solid var(--sidebar-border);
  overflow-y: auto;
  z-index: 40;
  padding: var(--space-5) 0;
  transform: translateX(-100%);
  transition: transform var(--duration-normal) var(--ease-default);
}
.sidebar.open { transform: translateX(0); }

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-5) var(--space-6);
  border-bottom: 1px solid var(--sidebar-border);
  margin-bottom: var(--space-3);
}
.sidebar-logo__mark {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-md);
  background: var(--primary);
  color: var(--primary-foreground);
  display: flex;
  align-items: center;
  justify-content: center;
}
.sidebar-logo__title { font-size: 15px; font-weight: 700; color: var(--sidebar-foreground); }
.sidebar-logo__sub { font-size: 11px; color: var(--muted-foreground); }

.sidebar-group-label {
  padding: var(--space-4) var(--space-5) var(--space-1);
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted-foreground);
}

.sidebar-toc a,
.sidebar-pages a {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-5);
  color: var(--muted-foreground);
  text-decoration: none;
  font-size: 13px;
  line-height: 1.5;
  border-left: 2px solid transparent;
  transition: background-color var(--duration-fast) var(--ease-default),
              color var(--duration-fast) var(--ease-default),
              border-color var(--duration-fast) var(--ease-default);
}
.sidebar-toc a:hover,
.sidebar-pages a:hover {
  background: var(--sidebar-accent);
  color: var(--sidebar-foreground);
}
.sidebar-toc a:focus-visible,
.sidebar-pages a:focus-visible { outline-offset: -2px; }

.sidebar-toc a.active {
  background: var(--sidebar-accent);
  color: var(--sidebar-accent-foreground);
  border-left-color: var(--sidebar-primary);
  font-weight: 500;
}
.sidebar-pages a.active {
  background: var(--sidebar-accent);
  color: var(--sidebar-accent-foreground);
  border-left-color: var(--sidebar-primary);
  font-weight: 600;
}
.sidebar-pages { border-top: 1px solid var(--sidebar-border); margin-top: var(--space-3); padding-top: var(--space-2); }
.sidebar-pages a .nav-emoji { font-size: 14px; line-height: 1; }

.main-content { margin-left: 0; min-height: 100vh; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding: var(--space-3) var(--space-8);
  background: color-mix(in oklab, var(--background) 85%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

/* ---------- §2 Search input ---------- */
.search-box { position: relative; flex: 1; max-width: 480px; }
.search-box .search-icon {
  position: absolute;
  left: var(--space-3);
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted-foreground);
  pointer-events: none;
}
.search-box input {
  width: 100%;
  height: 36px;
  padding: 0 var(--space-3) 0 40px;
  background: var(--background);
  border: 1px solid var(--input);
  border-radius: var(--radius-md);
  color: var(--foreground);
  font-size: 14px;
  font-family: var(--font-sans);
  outline: none;
}
.search-box input::placeholder { color: var(--muted-foreground); }
.search-box input:focus-visible {
  border-color: var(--ring);
  outline: 2px solid var(--ring);
  outline-offset: -1px;
}

.theme-toggle { border-radius: var(--radius-full); font-size: 18px; line-height: 1; flex-shrink: 0; }
.hamburger { flex-shrink: 0; display: inline-flex; }

/* ---------- Content area ---------- */
.content-area { max-width: 900px; margin: 0 auto; padding: var(--space-8) var(--space-8) 120px; }

/* ---------- §2 Section (card container) ---------- */
.section {
  margin-bottom: var(--space-8);
  background: var(--card);
  color: var(--card-foreground);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}
.section.hidden-section { display: none; }

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-5) var(--space-6);
  cursor: pointer;
  user-select: none;
  border-bottom: 1px solid transparent;
  transition: background-color var(--duration-fast) var(--ease-default);
}
.section-header:hover { background: var(--accent); }
.section-header:focus-visible { outline-offset: -2px; }
.section.open .section-header { border-bottom-color: var(--border); }

.section-header h2 {
  font-size: 20px;
  font-weight: 700;
  line-height: 1.3;
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  background: var(--muted);
  color: var(--foreground);
  font-size: 13px;
  font-weight: 600;
  flex-shrink: 0;
}

.section-toggle {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: var(--muted);
  color: var(--foreground);
  transition: transform var(--duration-normal) var(--ease-default);
}
.section.open .section-toggle { transform: rotate(180deg); }

.section-body { padding: var(--space-6); display: none; }
.section.open .section-body { display: block; }

/* typography inside sections */
.section-body p { margin-bottom: var(--space-4); color: var(--muted-foreground); }
.section-body ul, .section-body ol { margin-bottom: var(--space-4); padding-left: var(--space-6); color: var(--muted-foreground); }
.section-body li { margin-bottom: var(--space-2); }
.section-body strong { color: var(--foreground); font-weight: 600; }
.section-body h3 {
  font-size: 16px;
  font-weight: 600;
  line-height: 1.45;
  margin: var(--space-6) 0 var(--space-3);
  color: var(--foreground);
}
.section-body h3:first-child { margin-top: 0; }
.section-body h3 .num { margin-right: var(--space-1); }

/* ---------- §2 Typography helpers ---------- */
.t-display { font-size: clamp(1.875rem, 1.4rem + 2.4vw, 2.25rem); line-height: 1.15; letter-spacing: -0.02em; font-weight: 800; color: var(--foreground); }
.t-h2 { font-size: 20px; line-height: 1.3; font-weight: 700; }
.t-h3 { font-size: 16px; line-height: 1.45; font-weight: 600; }
.t-h4 { font-size: 14px; font-weight: 600; }
.t-lead { font-size: 18px; line-height: 1.6; }
.t-body { font-size: 16px; line-height: 1.7; }
.t-sm { font-size: 14px; }
.t-xs { font-size: 13px; }
.t-2xs { font-size: 11px; font-weight: 700; text-transform: uppercase; }
.text-muted { color: var(--muted-foreground); }

/* ---------- §2 Badge ---------- */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px var(--space-2);
  border-radius: var(--radius-sm);
  font-size: 11px;
  font-weight: 600;
  line-height: 1.5;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border: 1px solid transparent;
  white-space: nowrap;
}
.badge-secondary { background: var(--secondary); color: var(--secondary-foreground); }
.badge-default { background: var(--primary); color: var(--primary-foreground); }
.badge-outline { background: transparent; color: var(--foreground); border-color: var(--border); }
.badge-success { background: var(--success-bg); color: var(--success-text); border-color: var(--success-border); }
.badge-destructive { background: var(--destructive-bg); color: var(--destructive-text); border-color: var(--destructive-border); }
.badge-info { background: var(--info-bg); color: var(--info-text); border-color: var(--info-border); }
.badge-warning { background: var(--warning-bg); color: var(--warning-text); border-color: var(--warning-border); }
.badge-new { /* legacy → solid primary, no gradient */
  display: inline-flex;
  align-items: center;
  padding: 2px var(--space-2);
  border-radius: var(--radius-sm);
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  background: var(--primary);
  color: var(--primary-foreground);
  margin-right: var(--space-2);
  vertical-align: middle;
  line-height: 1.6;
}

/* ---------- §2 Alert ---------- */
.alert {
  position: relative;
  display: flex;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-5);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  margin-bottom: var(--space-4);
}
.alert-icon { flex-shrink: 0; line-height: 1.4; }
.alert-content { flex: 1; min-width: 0; }
.alert-title { font-weight: 600; margin-bottom: var(--space-1); color: var(--foreground); }
.alert-body, .alert p { color: var(--foreground); margin: 0; }
.alert ul, .alert ol { color: var(--foreground); margin-bottom: 0; }
.alert a { color: inherit; }

.alert-info { background: var(--info-bg); border-color: var(--info-border); }
.alert-info .alert-icon { color: var(--info); }
.alert-warning { background: var(--warning-bg); border-color: var(--warning-border); }
.alert-warning .alert-icon { color: var(--warning); }
.alert-success { background: var(--success-bg); border-color: var(--success-border); }
.alert-success .alert-icon { color: var(--success); }
.alert-destructive { background: var(--destructive-bg); border-color: var(--destructive-border); }
.alert-destructive .alert-icon { color: var(--destructive); }

/* dual cards (do/don't) */
.dual-cards { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-4); margin-bottom: var(--space-4); }
.dual-cards .alert { margin-bottom: 0; }
.dual-cards .alert ul { list-style: none; padding: 0; }
.dual-cards .alert li { display: flex; align-items: flex-start; padding: var(--space-1) 0; }

/* check / cross chips */
.icon-check, .icon-cross {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: var(--radius-full);
  font-size: 12px;
  font-weight: 700;
  margin-right: var(--space-2);
  flex-shrink: 0;
  vertical-align: middle;
}
.icon-check { background: var(--success-bg); color: var(--success); }
.icon-cross { background: var(--destructive-bg); color: var(--destructive); }

/* ---------- §2 Table ---------- */
.table-wrap {
  overflow-x: auto;
  margin-bottom: var(--space-4);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
}
table { width: 100%; border-collapse: collapse; font-size: 14px; }
thead { background: var(--muted); }
th {
  text-align: left;
  padding: var(--space-3) var(--space-4);
  font-weight: 700;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--foreground);
  white-space: nowrap;
  border-bottom: 1px solid var(--border);
}
td {
  padding: var(--space-3) var(--space-4);
  color: var(--foreground);
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
tbody tr { transition: background-color var(--duration-fast) var(--ease-default); }
tbody tr:nth-child(even) { background: var(--zebra); }
tbody tr:hover { background: var(--accent); }
tr:last-child td { border-bottom: none; }

@media (max-width: 767px) {
  .table-wrap { position: relative; }
  .table-wrap table th:first-child,
  .table-wrap table td:first-child {
    position: sticky;
    left: 0;
    z-index: 2;
    background: var(--card);
  }
  .table-wrap table thead th:first-child { background: var(--muted); z-index: 3; }
  .table-wrap table tbody tr:nth-child(even) td:first-child { background: var(--card); }
}

/* ---------- §2 Code ---------- */
.code-block {
  position: relative;
  margin-bottom: var(--space-4);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
}
.code-block pre {
  padding: var(--space-4) var(--space-5);
  background: var(--code-bg);
  color: var(--code-foreground);
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.6;
  font-family: var(--font-mono);
}
.code-copy { position: absolute; top: var(--space-2); right: var(--space-2); }

/* inline code (de-blue) */
code:not(pre code) {
  padding: 2px var(--space-2);
  background: var(--muted);
  color: var(--foreground);
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-family: var(--font-mono);
}

/* ---------- §2 Filter tabs ---------- */
.filter-tabs { display: flex; gap: var(--space-2); margin-bottom: var(--space-4); flex-wrap: wrap; }
.filter-tab {
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  font-size: 13px;
  font-family: var(--font-sans);
  cursor: pointer;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--muted-foreground);
  transition: background-color var(--duration-fast) var(--ease-default),
              color var(--duration-fast) var(--ease-default);
}
.filter-tab:hover { background: var(--accent); color: var(--foreground); }
.filter-tab.active { background: var(--secondary); color: var(--secondary-foreground); font-weight: 600; }

/* ---------- §2 Link ---------- */
.link, .source-link, .link-solution {
  color: var(--primary);
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-color: color-mix(in oklab, var(--primary) 40%, transparent);
  cursor: pointer;
}
.link:hover, .source-link:hover, .link-solution:hover { text-decoration-color: var(--primary); }
.source-link, .link-solution {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-size: 13px;
  text-decoration: none;
}
.source-link:hover, .link-solution:hover { text-decoration: underline; text-underline-offset: 4px; }
.link-solution { font-size: 12px; }

/* ---------- §2.2 Card (generic component family) ---------- */
.card {
  background: var(--card);
  color: var(--card-foreground);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
  padding: var(--space-6);
}
/* sub-parts scoped to .card so they out-specify .section-body descendant rules */
.card .card-title {
  margin: 0;
  font-size: 16px;
  line-height: 1.45;
  font-weight: 600;
  color: var(--foreground);
}
.card .card-description {
  margin: var(--space-1) 0 0;
  font-size: 14px;
  color: var(--muted-foreground); /* card 底 L≈1.0 → muted-foreground 過 AA (DESIGN.md §1.4) */
}
.card .card-content:not(:first-child) { margin-top: var(--space-4); }
.card .card-footer {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-top: var(--space-4);
  padding-top: var(--space-4);
  border-top: 1px solid var(--border);
}
.card-interactive,
.card.is-interactive {
  cursor: pointer;
  transition: transform var(--duration-normal) var(--ease-default),
              border-color var(--duration-normal) var(--ease-default);
}
.card-interactive:hover,
.card.is-interactive:hover {
  transform: translateY(-2px);
  border-color: var(--ring);
}

/* ---------- §5.2 Card layout grids ---------- */
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: var(--space-4); }
.tri-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-4); }
.pricing-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: var(--space-4); }
@media (max-width: 1024px) {
  .tri-cards { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 767px) {
  .tri-cards { grid-template-columns: 1fr; }
}

/* ---------- Tier cards ---------- */
.tier-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: var(--space-3); margin-bottom: var(--space-4); }
.tier-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-5);
  text-align: center;
  background: var(--card);
  box-shadow: var(--shadow-sm);
  transition: transform var(--duration-fast) var(--ease-default), border-color var(--duration-fast) var(--ease-default);
}
.tier-card:hover { transform: translateY(-2px); border-color: var(--ring); }
.tier-card .tier-name { font-size: 13px; color: var(--muted-foreground); margin-bottom: var(--space-2); }
.tier-card .tier-limit { font-size: 22px; font-weight: 700; color: var(--foreground); }
.tier-card .tier-unit { font-size: 12px; color: var(--muted-foreground); margin-top: var(--space-1); }
.tier-meter { width: 100%; height: 6px; border-radius: var(--radius-full); background: var(--muted); margin-top: var(--space-3); overflow: hidden; }
.tier-meter-fill { height: 100%; border-radius: var(--radius-full); background: var(--primary); transition: width var(--duration-slow) var(--ease-out); }
.tier-fill-1 { width: 1%; }
.tier-fill-15 { width: 15%; }
.tier-fill-33 { width: 33%; }
.tier-fill-100 { width: 100%; }

/* ---------- Quick-ref cards ---------- */
.quick-ref { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: var(--space-3); }
.quick-ref-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-4);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: background-color var(--duration-fast) var(--ease-default), border-color var(--duration-fast) var(--ease-default);
}
.quick-ref-card:hover { border-color: var(--ring); background: var(--accent); }
.quick-ref-label { font-size: 13px; color: var(--muted-foreground); }
.quick-ref-tool { font-size: 14px; font-weight: 500; color: var(--foreground); font-family: var(--font-mono); }

/* ---------- Architecture diagram ---------- */
.arch-diagram {
  display: flex;
  align-items: center;
  justify-content: center;
  margin: var(--space-6) 0;
  padding: var(--space-6) var(--space-4);
  background: var(--muted);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow-x: auto;
}
.arch-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-3) var(--space-5);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--card);
  text-align: center;
  min-width: 100px;
  flex-shrink: 0;
}
.arch-box--emphasis { border-color: var(--primary); }
.arch-box-label { font-size: 13px; font-weight: 600; color: var(--foreground); }
.arch-box-sub { font-size: 11px; color: var(--muted-foreground); margin-top: 2px; }
.arch-arrow-group { display: flex; flex-direction: column; align-items: center; gap: var(--space-3); padding: 0 var(--space-2); flex-shrink: 0; }
.arch-arrow-row { display: flex; align-items: center; gap: var(--space-1); }
.arch-arrow-line { width: 40px; height: 2px; background: var(--border); }
.arch-arrow-head { width: 0; height: 0; border-top: 5px solid transparent; border-bottom: 5px solid transparent; border-left: 8px solid var(--border); }
.arch-arrow-label { font-size: 11px; color: var(--muted-foreground); white-space: nowrap; }
.arch-server-group { display: flex; flex-direction: column; gap: var(--space-3); flex-shrink: 0; }

@media (max-width: 479px) {
  .arch-diagram { flex-direction: column; gap: var(--space-2); }
  .arch-arrow-group { flex-direction: row; gap: var(--space-4); padding: var(--space-1) 0; }
  .arch-arrow-row { flex-direction: column; }
  .arch-arrow-line { width: 2px; height: 24px; }
  .arch-arrow-head { border-left: 5px solid transparent; border-right: 5px solid transparent; border-top: 8px solid var(--border); border-bottom: none; }
  .arch-server-group { flex-direction: row; gap: var(--space-2); }
}

/* ---------- Step flow ---------- */
.step-flow { display: flex; flex-direction: column; margin-bottom: var(--space-4); }
.step-item { display: flex; gap: var(--space-4); position: relative; }
.step-indicator { display: flex; flex-direction: column; align-items: center; flex-shrink: 0; }
.step-num {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--secondary);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 700;
  color: var(--secondary-foreground);
}
.step-line { width: 2px; flex: 1; background: var(--border); min-height: 20px; }
.step-content { padding: var(--space-1) 0 var(--space-6); flex: 1; }
.step-content strong { display: block; margin-bottom: var(--space-1); }
.step-content span { color: var(--muted-foreground); }

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  width: 44px;
  height: 44px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
  z-index: 50;
  transition: opacity var(--duration-normal) var(--ease-out), transform var(--duration-normal) var(--ease-out);
}
.back-to-top.visible { opacity: 1; transform: translateY(0); pointer-events: auto; }

/* ---------- Sidebar overlay ---------- */
.sidebar-overlay { display: none; position: fixed; inset: 0; background: var(--overlay); z-index: 35; }
.sidebar-overlay.open { display: block; }

/* ---------- Entrance animation ---------- */
@keyframes fadeInUp { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: translateY(0); } }
.animate-in { animation: fadeInUp var(--duration-enter) var(--ease-out) both; }
.animate-delay-1 { animation-delay: 0.1s; }
.animate-delay-2 { animation-delay: 0.2s; }
.animate-delay-3 { animation-delay: 0.3s; }

/* ---------- Responsive (desktop ≥1024) ---------- */
@media (min-width: 1024px) {
  .sidebar { transform: none; }
  .main-content { margin-left: var(--sidebar-width); }
  .hamburger { display: none; }
  .sidebar-overlay.open { display: none; }
}

@media (max-width: 767px) {
  .topbar { padding: var(--space-3) var(--space-4); }
  .content-area { padding: var(--space-6) var(--space-4) 100px; }
  .dual-cards { grid-template-columns: 1fr; }
  .tier-cards { grid-template-columns: 1fr 1fr; }
  .section-header { padding: var(--space-4); }
  .section-body { padding: var(--space-4); }
  .section-header h2 { font-size: 16px; }
  .quick-ref { grid-template-columns: 1fr; }
}

@media (max-width: 479px) {
  .tier-cards { grid-template-columns: 1fr; }
}

/* ---------- Coarse pointer: 44px touch targets ---------- */
@media (pointer: coarse) {
  .btn { min-height: 44px; }
  .btn-icon { min-width: 44px; }
}

/* ---------- §4 Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
  .animate-in { opacity: 1; transform: none; }
  html { scroll-behavior: auto; }
}