/* Neutral Modern tokens + PingFang (user constraint) */
:root {
  --bg: #fafafa;
  --surface: #ffffff;
  --surface-warm: var(--surface);
  --fg: #111111;
  --fg-2: var(--fg);
  --muted: #6b6b6b;
  --meta: var(--muted);
  --border: #e5e5e5;
  --border-soft: var(--border);
  --accent: #2f6feb;
  --accent-on: #ffffff;
  --accent-hover: color-mix(in oklab, var(--accent), black 8%);
  --accent-active: color-mix(in oklab, var(--accent), black 14%);
  --success: #17a34a;
  --warn: #eab308;
  --danger: #dc2626;
  --font-display: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", -apple-system, system-ui, sans-serif;
  --font-body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", -apple-system, system-ui, sans-serif;
  --font-mono: ui-monospace, "JetBrains Mono", "SF Mono", Menlo, monospace;
  --text-xs: 12px;
  --text-sm: 14px;
  --text-base: 16px;
  --text-lg: 20px;
  --text-xl: 24px;
  --text-2xl: 32px;
  --text-3xl: 48px;
  --text-4xl: 64px;
  --leading-body: 1.5;
  --leading-tight: 1.2;
  --tracking-display: -0.01em;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-12: 48px;
  --space-20: 80px;
  --section-y-desktop: 80px;
  --section-y-tablet: 48px;
  --section-y-phone: 32px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-pill: 9999px;
  --elev-flat: none;
  --elev-ring: 0 0 0 1px var(--border);
  --elev-raised: 0 2px 8px color-mix(in oklab, var(--fg), transparent 92%);
  --focus-ring: 0 0 0 3px color-mix(in oklab, var(--accent), transparent 70%);
  --motion-fast: 150ms;
  --motion-base: 200ms;
  --ease-standard: cubic-bezier(0.2, 0, 0, 1);
  --container-max: 1200px;
  --container-gutter-desktop: 24px;
  --container-gutter-tablet: 16px;
  --container-gutter-phone: 12px;
  --accent-soft: color-mix(in oklch, var(--accent) 14%, transparent);
  --fg-soft: color-mix(in oklch, var(--fg) 6%, transparent);
  --fs-h1: clamp(40px, 5.5vw, 64px);
  --fs-h2: clamp(28px, 3.5vw, 40px);
  --fs-h3: 20px;
  --fs-lead: 18px;
  --fs-body: 16px;
  --fs-meta: 13px;
  --gap-xs: 8px;
  --gap-sm: 12px;
  --gap-md: 20px;
  --gap-lg: 32px;
  --gap-xl: 56px;
  --gap-2xl: 96px;
  --container: 1120px;
  --gutter: 32px;
  --radius: 8px;
  --sidebar-w: 240px;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: var(--leading-body);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; border: 0; background: none; }
p { text-wrap: pretty; margin: 0; }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  text-wrap: balance;
  margin: 0;
  letter-spacing: var(--tracking-display);
  line-height: var(--leading-tight);
}
input, select, textarea { font: inherit; color: inherit; }

.container {
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.section { padding-block: clamp(48px, 8vw, var(--gap-2xl)); }
.section + .section { border-top: 1px solid var(--border); }
.stack { display: flex; flex-direction: column; }
.stack > * + * { margin-top: var(--gap-md); }
.row { display: flex; align-items: center; gap: var(--gap-md); }
.row-between { display: flex; align-items: center; justify-content: space-between; gap: var(--gap-md); }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--gap-lg); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--gap-lg); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--gap-md); }
.grid-2-1 { display: grid; grid-template-columns: 2fr 1fr; gap: var(--gap-xl); align-items: start; }
.grid-1-2 { display: grid; grid-template-columns: 1fr 2fr; gap: var(--gap-xl); align-items: start; }
@media (max-width: 920px) {
  .grid-2, .grid-3, .grid-4, .grid-2-1, .grid-1-2 { grid-template-columns: 1fr; }
  .container { padding-inline: var(--container-gutter-phone); }
}

.h1, h1 { font-size: var(--fs-h1); font-weight: 600; }
.h2, h2 { font-size: var(--fs-h2); font-weight: 600; }
.h3, h3 { font-size: var(--fs-h3); font-weight: 600; }
.lead { font-size: var(--fs-lead); line-height: 1.55; color: var(--muted); max-width: 60ch; }
.eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 var(--gap-md);
}
.meta { font-family: var(--font-mono); font-size: var(--fs-meta); color: var(--muted); }
.num { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  font-size: var(--text-sm);
  font-weight: 500;
  transition: background var(--motion-fast) var(--ease-standard),
    border-color var(--motion-fast) var(--ease-standard),
    color var(--motion-fast) var(--ease-standard),
    transform 0.05s ease;
}
.btn:active { transform: translateY(1px); }
.btn:focus-visible { outline: none; box-shadow: var(--focus-ring); }
.btn-primary { background: var(--accent); color: var(--accent-on); border-color: var(--accent); }
.btn-primary:hover { background: var(--accent-hover); }
.btn-primary:active { background: var(--accent-active); }
.btn-secondary { background: transparent; color: var(--fg); border-color: var(--border); }
.btn-secondary:hover { border-color: var(--fg); }
.btn-ghost { background: transparent; color: var(--fg); padding-inline: 8px; }
.btn-ghost:hover { color: var(--accent); }
.btn-arrow::after { content: "→"; transition: transform var(--motion-fast) var(--ease-standard); }
.btn-arrow:hover::after { transform: translateX(2px); }
.btn-block { width: 100%; }
.btn-sm { padding: 8px 12px; font-size: var(--text-xs); }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-5);
}
.card-flat { background: transparent; border: 0; padding: 0; }

.feature .feature-mark {
  width: 36px; height: 36px;
  display: grid; place-items: center;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--accent);
  margin-bottom: var(--gap-md);
}
.feature .feature-mark svg { width: 18px; height: 18px; }
.feature h3 { margin-bottom: 6px; }
.feature p { color: var(--muted); font-size: 15px; }

.pill {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 4px 10px;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: var(--radius-pill);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.tag {
  display: inline-flex; align-items: center;
  padding: 4px 10px;
  color: var(--muted);
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  font-size: 12px;
}
.badge {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 2px 8px;
  border-radius: var(--radius-pill);
  font-size: 12px;
  font-weight: 500;
}
.badge-muted { background: var(--fg-soft); color: var(--muted); }
.badge-success { background: color-mix(in oklab, var(--success) 14%, transparent); color: var(--success); }

.field { display: flex; flex-direction: column; gap: 6px; }
.field label { font-size: 13px; color: var(--muted); }
.field-help { font-size: 12px; color: var(--muted); }
.field-error { font-size: 12px; color: var(--danger); display: none; }
.field.is-invalid .field-error { display: block; }
.field.is-invalid .input,
.field.is-invalid .textarea,
.field.is-invalid .select {
  border-color: var(--danger);
}
.input, .textarea, .select {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--fg);
  font-size: 15px;
  transition: border-color var(--motion-fast) var(--ease-standard);
}
.input:focus, .textarea:focus, .select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: var(--focus-ring);
}
.input::placeholder, .textarea::placeholder { color: color-mix(in oklab, var(--muted), transparent 30%); }
.textarea { min-height: 96px; resize: vertical; line-height: 1.55; }
.select { appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%); background-position: calc(100% - 18px) calc(50% - 3px), calc(100% - 12px) calc(50% - 3px); background-size: 6px 6px, 6px 6px; background-repeat: no-repeat; padding-right: 36px; }

.ph-img {
  background: linear-gradient(135deg, var(--accent-soft), var(--fg-soft)), var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  aspect-ratio: 16 / 10;
  display: grid; place-items: center;
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
}
.ph-img.wide { aspect-ratio: 16 / 9; }

.topnav {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in oklch, var(--bg) 92%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.topnav-inner { display: flex; align-items: center; justify-content: space-between; padding-block: 14px; gap: var(--gap-md); }
.topnav .logo { font-family: var(--font-display); font-size: 18px; font-weight: 600; letter-spacing: -0.01em; }
.topnav nav { display: flex; gap: var(--gap-lg); }
.topnav nav a { font-size: 14px; color: var(--muted); }
.topnav nav a:hover { color: var(--fg); }
.pagefoot { padding-block: var(--gap-xl); color: var(--muted); font-size: 13px; border-top: 1px solid var(--border); }

.hero { padding-block: clamp(72px, 11vw, 140px); }
.hero-center { text-align: center; max-width: 34ch; margin-inline: auto; }
.hero h1 { margin-bottom: var(--gap-md); }
.hero .lead { margin-bottom: var(--gap-lg); margin-inline: auto; }
.hero-cta { display: inline-flex; gap: var(--gap-sm); flex-wrap: wrap; }
.hero-center .hero-cta { justify-content: center; }
.hero-split { display: grid; grid-template-columns: 1fr 1fr; gap: var(--gap-2xl); align-items: center; }
@media (max-width: 920px) {
  .hero-split { grid-template-columns: 1fr; }
  .topnav nav { display: none; }
}

.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;
}