/* ── Design Tokens ── */
:root {
  --primary: #0891B2;
  --primary-hover: #0E7490;
  --primary-light: #ECFEFF;
  --primary-glow: rgba(8, 145, 178, 0.15);
  --bg-accent: rgba(34, 211, 238, 0.08);
  --secondary: #22D3EE;
  --cta: #22C55E;
  --cta-hover: #16A34A;
  --bg: #F0FDFA;
  --bg-card: rgba(255, 255, 255, 0.72);
  --bg-card-solid: #ffffff;
  --bg-input: rgba(8, 145, 178, 0.06);
  --text: #134E4A;
  --text-secondary: #5A7A77;
  --border: rgba(8, 145, 178, 0.12);
  --border-solid: #CCE8E3;
  --danger: #EF4444;
  --danger-bg: #FEF2F2;
  --danger-border: #FECACA;
  --success: #22C55E;
  --success-bg: #F0FDF4;
  --success-border: #BBF7D0;
  --warning: #F59E0B;
  --radius: 16px;
  --radius-sm: 10px;
  --radius-xs: 6px;
  --shadow-sm: 0 1px 2px rgba(8, 145, 178, 0.06);
  --shadow: 0 1px 3px rgba(8, 145, 178, 0.08), 0 1px 2px rgba(8, 145, 178, 0.04);
  --shadow-md: 0 4px 16px rgba(8, 145, 178, 0.1), 0 2px 4px rgba(8, 145, 178, 0.06);
  --shadow-lg: 0 12px 40px rgba(8, 145, 178, 0.12), 0 4px 12px rgba(8, 145, 178, 0.06);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --font-cn: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --mono: "SF Mono", "Fira Code", "Cascadia Code", Consolas, "JetBrains Mono", monospace;
  --max-width: 1200px;
  --blur: 16px;
  --glass-border: 1px solid rgba(255, 255, 255, 0.25);
}

[data-theme="dark"] {
  --primary: #A78BFA;
  --primary-hover: #C4B5FD;
  --primary-light: rgba(167, 139, 250, 0.14);
  --primary-glow: rgba(167, 139, 250, 0.16);
  --bg-accent: rgba(255, 255, 255, 0.05);
  --secondary: #E879F9;
  --bg: #000000;
  --bg-card: rgba(12, 12, 12, 0.82);
  --bg-card-solid: #0B0B0B;
  --bg-input: rgba(255, 255, 255, 0.06);
  --text: #F9FAFB;
  --text-secondary: #D1D5DB;
  --border: rgba(255, 255, 255, 0.12);
  --border-solid: #27272A;
  --danger-bg: #450A0A;
  --danger-border: #7F1D1D;
  --success-bg: #052E16;
  --success-border: #14532D;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.35);
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.45);
  --shadow-md: 0 4px 18px rgba(0, 0, 0, 0.55);
  --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.7);
  --glass-border: 1px solid rgba(255, 255, 255, 0.10);
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.72;
  font-size: 16px;
  font-weight: 400;
  letter-spacing: -0.005em;
  text-rendering: optimizeLegibility;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background-image:
    radial-gradient(ellipse at 20% 0%, var(--primary-glow) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 100%, var(--bg-accent) 0%, transparent 50%);
  background-attachment: fixed;
}

h1, h2, h3, .logo-text {
  font-family: var(--font-cn);
  letter-spacing: -0.025em;
}

p { text-wrap: pretty; }

strong { font-weight: 800; }

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── Focus Ring ── */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-xs);
}

/* ── Header ── */
.site-header {
  background: var(--bg-card);
  backdrop-filter: blur(var(--blur));
  -webkit-backdrop-filter: blur(var(--blur));
  border-bottom: var(--glass-border);
  padding: 0 1.5rem;
  position: sticky; top: 0; z-index: 100;
}
.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.logo {
  display: flex; align-items: center; gap: .6rem;
  font-size: 1.22rem; font-weight: 800; color: var(--text);
  letter-spacing: -.03em;
  cursor: pointer; transition: opacity .2s;
}
.logo:hover { opacity: .8; text-decoration: none; }
.logo img { width: 34px; height: 34px; }
.logo-text {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}

.header-actions { display: flex; align-items: center; gap: .75rem; }
.nav-link {
  font-size: .875rem; font-weight: 600; color: var(--text-secondary);
  letter-spacing: -.01em;
  padding: .4rem .75rem; border-radius: var(--radius-xs);
  cursor: pointer; transition: color .2s, background .2s;
}
.nav-link:hover { color: var(--primary); background: var(--primary-light); text-decoration: none; }
.theme-toggle {
  display: inline-flex; align-items: center; gap: .35rem;
  background: var(--bg-input); border: var(--glass-border);
  border-radius: 2rem; padding: .4rem .85rem;
  cursor: pointer; font-size: .82rem; font-family: var(--font);
  font-weight: 600; letter-spacing: -.01em;
  color: var(--text-secondary); transition: all .2s;
}
.theme-toggle:hover { color: var(--text); border-color: var(--primary); }
.theme-toggle svg { width: 16px; height: 16px; flex-shrink: 0; }

/* ── Main ── */
.site-main { flex: 1; padding: 2rem 1.5rem 3rem; max-width: var(--max-width); margin: 0 auto; width: 100%; }

/* ── Footer ── */
.site-footer {
  background: var(--bg-card);
  backdrop-filter: blur(var(--blur));
  -webkit-backdrop-filter: blur(var(--blur));
  border-top: var(--glass-border);
  padding: 1.5rem;
  text-align: center;
  font-size: .8rem; font-weight: 500;
  color: var(--text-secondary);
}

/* ── Breadcrumb ── */
.breadcrumb {
  display: flex; gap: .5rem; font-size: .8rem; font-weight: 500;
  color: var(--text-secondary); margin-bottom: .75rem; flex-wrap: wrap;
}
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--primary); }
.breadcrumb span:last-child { color: var(--text); }

/* ── Tool Header ── */
.tool-header { margin-bottom: 1.5rem; }
.tool-header h1 { font-size: clamp(1.65rem, 2.4vw, 2.15rem); font-weight: 800; margin-bottom: .45rem; letter-spacing: -.035em; line-height: 1.18; }
.tool-header p { color: var(--text-secondary); font-size: 1rem; max-width: 720px; line-height: 1.75; }

/* ── Hero ── */
.hero { text-align: center; padding: 2.5rem 0 3.5rem; }
.hero-badge {
  display: inline-block; padding: .32rem .95rem; font-size: .82rem; font-weight: 700;
  letter-spacing: -.01em;
  background: var(--primary-light); color: var(--primary);
  border-radius: 2rem; margin-bottom: 1rem;
}
.hero h1 { font-size: clamp(2.25rem, 5vw, 4.15rem); font-weight: 800; margin-bottom: .85rem; letter-spacing: -.055em; line-height: 1.08; }
.hero h1 span {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p { color: var(--text-secondary); font-size: clamp(1.05rem, 1.8vw, 1.18rem); max-width: 620px; margin: 0 auto 2rem; line-height: 1.85; letter-spacing: -.015em; }
.hero-stats {
  display: flex; justify-content: center; gap: 2.5rem; margin-bottom: 2rem;
  font-size: .88rem; font-weight: 500; color: var(--text-secondary);
}
.hero-stats strong { display: block; font-size: 1.55rem; font-weight: 800; color: var(--text); line-height: 1.15; letter-spacing: -.035em; }

.search-wrap { position: relative; display: inline-block; width: 100%; max-width: 500px; }
.search-wrap svg {
  position: absolute; left: 1rem; top: 50%; transform: translateY(-50%);
  width: 20px; height: 20px; color: var(--text-secondary); pointer-events: none;
}
.search-box {
  width: 100%; padding: .85rem 1rem .85rem 2.75rem;
  border: 2px solid var(--border); border-radius: 2.5rem;
  font-size: 1rem; font-family: var(--font);
  background: var(--bg-card); color: var(--text);
  backdrop-filter: blur(var(--blur));
  -webkit-backdrop-filter: blur(var(--blur));
  outline: none; cursor: text;
  transition: border-color .2s, box-shadow .2s;
}
.search-box:focus { border-color: var(--primary); box-shadow: 0 0 0 4px var(--primary-glow); }
.search-box::placeholder { color: var(--text-secondary); }

/* ── Tool Grid ── */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 1.25rem;
  margin-top: .5rem;
}
.tool-card {
  background: var(--bg-card);
  backdrop-filter: blur(var(--blur));
  -webkit-backdrop-filter: blur(var(--blur));
  border: var(--glass-border);
  border-radius: var(--radius);
  padding: 1.5rem 1.35rem;
  transition: transform .2s, box-shadow .2s, border-color .2s;
  display: flex; align-items: flex-start; gap: 1rem;
  color: var(--text);
  cursor: pointer;
}
.tool-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-3px);
  border-color: var(--primary);
  text-decoration: none;
}
.tool-card:active { transform: translateY(-1px); }
.tool-card-icon {
  flex-shrink: 0; width: 44px; height: 44px;
  display: flex; align-items: center; justify-content: center;
  background: var(--primary-light); border-radius: var(--radius-sm);
  color: var(--primary); transition: background .2s, color .2s;
}
.tool-card:hover .tool-card-icon { background: var(--primary); color: #fff; }
.tool-card-icon svg { width: 22px; height: 22px; }
.tool-card-body h3 { font-size: 1.05rem; font-weight: 700; margin-bottom: .28rem; letter-spacing: -.025em; line-height: 1.35; }
.tool-card-body p { font-size: .86rem; font-weight: 400; color: var(--text-secondary); line-height: 1.65; letter-spacing: -.01em; }

/* ── Tool Area ── */
.tool-area {
  background: var(--bg-card);
  backdrop-filter: blur(var(--blur));
  -webkit-backdrop-filter: blur(var(--blur));
  border: var(--glass-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}
.tool-area label {
  display: block; font-size: .82rem; font-weight: 700;
  margin-bottom: .45rem; color: var(--text-secondary);
  letter-spacing: -.01em;
}
.tool-area textarea,
.tool-area input[type="text"],
.tool-area input[type="number"],
.tool-area input[type="color"],
.tool-area select {
  width: 100%;
  padding: .7rem .85rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: .95rem;
  font-family: var(--mono);
  background: var(--bg-input);
  color: var(--text);
  outline: none;
  transition: border-color .2s, box-shadow .2s;
  resize: vertical;
  cursor: text;
}
.tool-area textarea:focus,
.tool-area input:focus,
.tool-area select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-glow);
}
.tool-area textarea { min-height: 160px; }
.tool-area input[type="color"] { width: 100%; height: 48px; padding: .3rem; cursor: pointer; }

/* ── Buttons ── */
.btn {
  display: inline-flex; align-items: center; gap: .4rem;
  padding: .62rem 1.38rem; border: none; border-radius: var(--radius-sm);
  font-size: .88rem; font-weight: 700; cursor: pointer;
  transition: all .2s ease; font-family: var(--font);
  letter-spacing: -.015em;
}
.btn:active { transform: scale(.97); }
.btn-primary { background: var(--primary); color: #fff; box-shadow: var(--shadow-sm); }
.btn-primary:hover { background: var(--primary-hover); box-shadow: var(--shadow-md); }
.btn-outline { background: transparent; border: 1px solid var(--border); color: var(--text); }
.btn-outline:hover { background: var(--bg-input); border-color: var(--primary); }
.btn-sm { padding: .35rem .85rem; font-size: .78rem; }
.btn-group { display: flex; gap: .5rem; flex-wrap: wrap; margin: .75rem 0; }

/* ── Alerts ── */
.alert { padding: .75rem 1rem; border-radius: var(--radius-sm); font-size: .8rem; font-weight: 500; margin: .5rem 0; }
.alert-error { background: var(--danger-bg); color: var(--danger); border: 1px solid var(--danger-border); }
.alert-success { background: var(--success-bg); color: #16A34A; border: 1px solid var(--success-border); }

/* ── Related Tools ── */
.related-tools { margin-top: 2rem; }
.related-tools h2 { font-size: 1.22rem; font-weight: 800; margin-bottom: 1rem; letter-spacing: -.03em; }
.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: .75rem;
}
.related-card {
  background: var(--bg-card);
  backdrop-filter: blur(var(--blur));
  -webkit-backdrop-filter: blur(var(--blur));
  border: var(--glass-border);
  border-radius: var(--radius-sm);
  padding: 1rem;
  display: flex; align-items: center; gap: .6rem;
  color: var(--text); font-size: .9rem; font-weight: 650;
  letter-spacing: -.015em;
  cursor: pointer; transition: all .2s;
}
.related-card:hover { border-color: var(--primary); box-shadow: var(--shadow-md); text-decoration: none; }
.related-card svg { width: 20px; height: 20px; color: var(--primary); flex-shrink: 0; }

/* ── SEO Content ── */
.seo-content {
  margin-top: 2rem;
  display: grid;
  gap: 1rem;
}
.seo-card {
  background: var(--bg-card);
  backdrop-filter: blur(var(--blur));
  -webkit-backdrop-filter: blur(var(--blur));
  border: var(--glass-border);
  border-radius: var(--radius);
  padding: 1.35rem 1.5rem;
  box-shadow: var(--shadow-sm);
}
.seo-card h2 {
  font-size: 1.22rem;
  font-weight: 800;
  margin-bottom: .7rem;
  letter-spacing: -.03em;
}
.seo-card h3 {
  font-size: 1rem;
  font-weight: 750;
  margin: .9rem 0 .3rem;
}
.seo-card p,
.seo-card li {
  color: var(--text-secondary);
  line-height: 1.85;
}
.seo-card ul,
.seo-card ol {
  padding-left: 1.25rem;
  display: grid;
  gap: .35rem;
}
.seo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 1rem;
}
.faq-list {
  display: grid;
  gap: .7rem;
}
.faq-list details {
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .85rem 1rem;
}
.faq-list summary {
  cursor: pointer;
  font-weight: 750;
  color: var(--text);
}
.faq-list p { margin-top: .45rem; }

/* ── Split Panels ── */
.split-panels { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
@media (max-width: 768px) { .split-panels { grid-template-columns: 1fr; } }

/* ── Color Preview ── */
.color-preview {
  width: 100%; height: 80px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); margin: .5rem 0;
}

/* ── Diff Output ── */
.diff-output {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  font-family: var(--mono);
  font-size: .9rem;
  line-height: 1.75;
  max-height: 500px;
  overflow-y: auto;
}
.diff-line { padding: .15rem .85rem; white-space: pre-wrap; }
.diff-add { background: rgba(34, 197, 94, 0.12); }
.diff-remove { background: rgba(239, 68, 68, 0.12); }

/* ── Output Panels ── */
.code-output,
.preview-panel {
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 1rem;
  margin-top: .75rem;
  font-family: var(--mono);
  font-size: .92rem;
  line-height: 1.75;
  white-space: pre-wrap;
  overflow: auto;
}
.preview-panel { min-height: 400px; font-family: var(--font); line-height: 1.78; letter-spacing: -.005em; }
.preview-panel h1,
.preview-panel h2,
.preview-panel h3 { margin: .75rem 0 .4rem; line-height: 1.3; }
.preview-panel p,
.preview-panel ul,
.preview-panel ol { margin-bottom: .75rem; }
.preview-panel code { font-family: var(--mono); background: var(--primary-light); padding: .1rem .25rem; border-radius: 4px; }
.preview-panel pre { background: var(--bg-card-solid); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: .75rem; overflow: auto; margin-bottom: .75rem; }

/* ── Text Helpers ── */
.muted-text { color: var(--text-secondary); }
.danger-text { color: var(--danger); }
.result-output { margin-top: .75rem; }
.error-page { display: grid; place-items: center; min-height: 70vh; }
.error-card { width: min(100%, 520px); text-align: center; padding: 3rem 2rem; }
.error-card h1 { font-size: clamp(4rem, 16vw, 7rem); line-height: 1; color: var(--primary); margin-bottom: .75rem; }
.error-title { font-size: 1.25rem; font-weight: 700; margin-bottom: .4rem; }
.error-card .btn { margin-top: 1.5rem; }

/* ── Regex Highlight ── */
mark { background: rgba(8, 145, 178, 0.25); color: inherit; border-radius: 2px; }

/* ── Responsive ── */
@media (max-width: 640px) {
  .hero { padding: 1.5rem 0 2rem; }
  .hero h1 { font-size: 2rem; letter-spacing: -.045em; }
  .hero p { font-size: 1rem; }
  .hero-stats { gap: 1.5rem; }
  .hero-stats strong { font-size: 1.2rem; }
  .search-wrap svg { width: 17px; height: 17px; left: .75rem; }
  .search-box { padding: .7rem .75rem .7rem 2.2rem; font-size: .9rem; border-radius: 2rem; }
  .tool-header h1 { font-size: 1.45rem; }
  .tool-area { padding: 1rem; }
  .tool-card { padding: 1.25rem 1rem; }
  .tool-card-body h3 { font-size: 1rem; }
}

/* ── Reduced Motion ── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ── Selection ── */
::selection { background: var(--primary); color: #fff; }