:root {
  color-scheme: light;
  --bg: #f5f7fb;
  --bg-glow: radial-gradient(circle at top, rgba(37,99,235,.08), transparent 42%);
  --card: rgba(255,255,255,.78);
  --line: rgba(230,235,242,.9);
  --text: #111827;
  --muted: #6b7280;
  --accent: #2563eb;
  --accent-soft: #eff6ff;
  --accent-line: #dbeafe;
  --nav: rgba(255,255,255,.72);
  --input: #fbfcfe;
  --shadow: 0 12px 36px rgba(17, 24, 39, 0.08);
  --max: 1120px;
  --radius: 20px;
  --ease: cubic-bezier(.22, 1, .36, 1);
  --status-ok: #6b7280;
  --status-error: #dc2626;
  --focus-ring: 0 0 0 4px rgba(37,99,235,.14);
  --panel-shadow: 0 8px 24px rgba(17,24,39,.04);
  --btn-shadow: 0 6px 18px rgba(17,24,39,.06);
  --btn-primary-shadow: 0 10px 24px rgba(37,99,235,.22);
  --canvas-center: #fff;
  --canvas-center-line: #d1d5db;
  --canvas-text: #111827;
  --canvas-empty: #6b7280;
  --pointer: #ef4444;
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0b1220;
  --bg-glow: radial-gradient(circle at top, rgba(96,165,250,.16), transparent 38%);
  --card: rgba(17,24,39,.72);
  --line: rgba(36,48,65,.95);
  --text: #e5eefb;
  --muted: #94a3b8;
  --accent: #60a5fa;
  --accent-soft: rgba(96,165,250,.12);
  --accent-line: rgba(96,165,250,.24);
  --nav: rgba(11,18,32,.62);
  --input: rgba(15,23,42,.88);
  --shadow: 0 18px 48px rgba(0,0,0,.34);
  --status-ok: #94a3b8;
  --status-error: #f87171;
  --focus-ring: 0 0 0 4px rgba(96,165,250,.18);
  --panel-shadow: 0 10px 32px rgba(0,0,0,.22);
  --btn-shadow: 0 8px 20px rgba(0,0,0,.22);
  --btn-primary-shadow: 0 12px 28px rgba(96,165,250,.2);
  --canvas-center: #0f172a;
  --canvas-center-line: #334155;
  --canvas-text: #e5eefb;
  --canvas-empty: #94a3b8;
  --pointer: #fb7185;
}
* { box-sizing: border-box; }
html { background: var(--bg); }
body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg-glow), var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;
  transition: background-color .45s var(--ease), color .3s var(--ease);
}
a { color: inherit; text-decoration: none; }
button, input, textarea { font: inherit; }
.wrap { width: min(var(--max), calc(100% - 32px)); margin: 0 auto; }
.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid var(--line);
  background: var(--nav);
  backdrop-filter: blur(16px) saturate(150%);
  transition: background-color .35s var(--ease), border-color .35s var(--ease);
}
.nav .wrap {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.nav-side { display: flex; align-items: center; gap: 12px; }
.brand-wrap { display: flex; flex-direction: column; gap: 2px; }
.brand-line { display: flex; align-items: center; gap: 12px; }
.brand { font-size: 1rem; font-weight: 700; letter-spacing: .08em; }
.tag, .back, .sub, .box-title, .hint, footer, .nav-meta { color: var(--muted); transition: color .3s var(--ease); }
.nav-meta { font-size: .82rem; line-height: 1.3; }
.back { display: inline-flex; align-items: center; gap: 6px; }
.back:hover, .current-link:hover { color: var(--text); }
.current-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 12px;
  border: 1px solid var(--accent-line);
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 999px;
  font-size: .88rem;
  line-height: 1;
}
.nav-actions { display: flex; align-items: center; gap: 10px; }
.theme-toggle {
  position: relative;
  width: 52px;
  height: 52px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  background: var(--card);
  color: var(--text);
  border-radius: 999px;
  cursor: pointer;
  overflow: hidden;
  box-shadow: var(--btn-shadow);
  transition: transform .28s var(--ease), border-color .28s var(--ease), background-color .35s var(--ease), box-shadow .35s var(--ease);
  -webkit-tap-highlight-color: transparent;
}
.theme-toggle:hover { transform: translateY(-2px) scale(1.02); box-shadow: var(--shadow); }
.theme-toggle:active { transform: scale(.96); }
.theme-toggle:focus-visible { outline: none; box-shadow: var(--focus-ring), var(--shadow); }
.theme-toggle .icon {
  position: absolute;
  width: 22px;
  height: 22px;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.9;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform .42s var(--ease), opacity .28s var(--ease), color .28s var(--ease);
}
.theme-toggle .sun { color: #f59e0b; transform: rotate(-60deg) scale(.45); opacity: 0; }
.theme-toggle .moon { color: #2563eb; transform: rotate(0deg) scale(1); opacity: 1; }
:root[data-theme="dark"] .theme-toggle .sun { transform: rotate(0deg) scale(1); opacity: 1; }
:root[data-theme="dark"] .theme-toggle .moon { transform: rotate(60deg) scale(.45); opacity: 0; }
.hero { padding: 56px 0 24px; animation: fadeUp .5s var(--ease) both; }
h1 { margin: 0 0 10px; font-size: clamp(2rem, 6vw, 3rem); line-height: 1.05; letter-spacing: -.04em; }
.panel, .card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  backdrop-filter: blur(12px);
  box-shadow: var(--panel-shadow);
  transition: transform .24s var(--ease), border-color .24s var(--ease), box-shadow .35s var(--ease), background-color .35s var(--ease);
}
.panel { padding: 24px; }
.card { padding: 22px; }
.card:hover, .panel.is-hoverable:hover {
  transform: translateY(-4px);
  border-color: var(--accent-line);
  box-shadow: var(--shadow);
}
.label {
  display: inline-block;
  font-size: .76rem;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid var(--accent-line);
  border-radius: 999px;
  padding: 6px 10px;
}
.search-bar {
  margin: 0 auto 22px;
  width: min(680px, 100%);
}
.search-input {
  width: 100%;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--card);
  color: var(--text);
  box-shadow: var(--btn-shadow);
  transition: background-color .35s var(--ease), border-color .28s var(--ease), color .28s var(--ease), box-shadow .28s var(--ease);
}
.search-input:hover { border-color: var(--accent-line); }
.search-input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: var(--focus-ring), var(--btn-shadow);
}
.empty-state {
  display: none;
  padding: 22px;
  text-align: center;
  color: var(--muted);
  border: 1px dashed var(--accent-line);
  border-radius: var(--radius);
  background: var(--accent-soft);
}
.btn {
  border: 1px solid var(--line);
  background: var(--card);
  color: var(--text);
  padding: 10px 14px;
  border-radius: 12px;
  cursor: pointer;
  box-shadow: var(--btn-shadow);
  transition: transform .2s var(--ease), background-color .35s var(--ease), border-color .28s var(--ease), color .28s var(--ease), box-shadow .28s var(--ease);
}
.btn:hover { transform: translateY(-1px); border-color: var(--accent-line); }
.btn:active { transform: translateY(0) scale(.98); }
.btn:focus-visible, .field:focus-visible, textarea:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}
.btn.primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  box-shadow: var(--btn-primary-shadow);
}
.btn.primary:hover { filter: brightness(1.03); }
.field, textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 14px;
  background: var(--input);
  color: var(--text);
  outline: none;
  transition: background-color .35s var(--ease), border-color .28s var(--ease), color .3s var(--ease), box-shadow .28s var(--ease);
}
.field:hover, textarea:hover { border-color: var(--accent-line); }
.field:focus, textarea:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(37,99,235,.10); }
.actions { display: flex; flex-wrap: wrap; gap: 10px; margin: 14px 0 10px; }
.status { min-height: 24px; color: var(--status-ok); font-size: .94rem; transition: color .3s var(--ease); }
footer { padding: 24px 0 40px; text-align: center; font-size: .9rem; }
.related-tools {
  margin-top: 22px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}
.related-link {
  display: block;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--card);
  box-shadow: var(--btn-shadow);
  transition: transform .2s var(--ease), border-color .24s var(--ease), box-shadow .24s var(--ease), background-color .3s var(--ease);
}
.related-link:hover {
  transform: translateY(-2px);
  border-color: var(--accent-line);
  box-shadow: var(--shadow);
}
.related-link strong {
  display: block;
  margin-bottom: 6px;
  font-size: .96rem;
}
.related-link span {
  color: var(--muted);
  font-size: .88rem;
  line-height: 1.6;
}
@keyframes fadeUp { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}
@media (max-width: 900px) {
  .nav .wrap { min-height: 60px; padding: 12px 0; }
  .tag, .nav-meta { display: none; }
  .theme-toggle { width: 46px; height: 46px; }
  .current-link { padding: 8px 10px; font-size: .84rem; }
  .search-bar { margin-bottom: 18px; }
  .related-tools { grid-template-columns: 1fr; }
}