/* ═══════════════════════════════════════════════════
   SEOBAIKE Design System v2.0 — Porsche-Class
   Premium dark theme with warm gold accents
   ═══════════════════════════════════════════════════ */

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

/* ── Design Tokens ── */
:root {
  /* Brand Gold Spectrum */
  --gold-100: #ffd700;
  --gold-200: #f5a623;
  --gold-300: #e8850c;
  --gold-400: #d4780a;
  --gold-500: #b86a08;
  --gold-gradient: linear-gradient(135deg, #e8850c 0%, #f5a623 50%, #ffd700 100%);
  --gold-glow: 0 0 30px rgba(232,133,12,0.15);

  /* Surfaces */
  --bg-primary: #06060f;
  --bg-secondary: #0c0c1d;
  --bg-card: rgba(14, 14, 32, 0.8);
  --bg-card-hover: rgba(20, 20, 44, 0.9);
  --bg-elevated: rgba(22, 22, 48, 0.95);
  --bg-glass: rgba(255,255,255,0.02);

  /* Borders */
  --border-subtle: rgba(255,255,255,0.06);
  --border-default: rgba(255,255,255,0.08);
  --border-hover: rgba(232,133,12,0.3);
  --border-active: rgba(232,133,12,0.5);

  /* Text */
  --text-primary: #ffffff;
  --text-secondary: #b0b0cc;
  --text-muted: #6b6b8a;
  --text-gold: #f5a623;

  /* Status */
  --success: #34d058;
  --warning: #f0b429;
  --danger: #f85149;
  --info: #58a6ff;

  /* Spacing (8px grid) */
  --sp-1: 4px;
  --sp-2: 8px;
  --sp-3: 12px;
  --sp-4: 16px;
  --sp-5: 20px;
  --sp-6: 24px;
  --sp-8: 32px;
  --sp-10: 40px;
  --sp-12: 48px;
  --sp-16: 64px;
  --sp-20: 80px;
  --sp-24: 96px;

  /* Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Typography */
  --font-sans: "SF Pro Display", -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "JetBrains Mono", monospace;

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 20px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 40px rgba(0,0,0,0.5);
  --shadow-gold: 0 4px 24px rgba(232,133,12,0.12);

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  --duration-fast: 0.15s;
  --duration-normal: 0.3s;
  --duration-slow: 0.5s;
}

/* ── Base ── */
html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-secondary);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
  font-size: 15px;
}

/* ── Typography ── */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.2;
}
h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.6rem); }
h3 { font-size: clamp(1.2rem, 2vw, 1.5rem); }
h4 { font-size: 1.1rem; }

p { color: var(--text-secondary); line-height: 1.7; }

a {
  color: var(--gold-200);
  text-decoration: none;
  transition: color var(--duration-fast);
}
a:hover { color: var(--gold-100); }

.text-gold {
  background: var(--gold-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.text-muted { color: var(--text-muted); }

/* ── Layout ── */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--sp-6);
}
.container-narrow {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--sp-6);
}
.section {
  padding: var(--sp-24) 0;
  position: relative;
}
.section-sm { padding: var(--sp-16) 0; }
.section-lg { padding: 120px 0; }

/* ── Section Header ── */
.section-header {
  text-align: center;
  max-width: 640px;
  margin: 0 auto var(--sp-16);
}
.section-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: rgba(232,133,12,0.08);
  border: 1px solid rgba(232,133,12,0.15);
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--gold-200);
  letter-spacing: 1.5px;
  text-transform: uppercase;
  margin-bottom: var(--sp-4);
}
.section-header h2 { margin-bottom: var(--sp-3); }
.section-header p { font-size: 1.05rem; color: var(--text-muted); }

/* ── Navigation ── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 0 var(--sp-8);
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(6,6,15,0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-subtle);
  transition: all var(--duration-normal) var(--ease-out);
}
.nav.scrolled {
  background: rgba(6,6,15,0.95);
  box-shadow: var(--shadow-sm);
}
.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.5rem;
  font-weight: 900;
  letter-spacing: -0.5px;
  text-decoration: none;
}
.nav-brand img {
  width: 34px;
  height: 34px;
  border-radius: var(--radius-sm);
  box-shadow: 0 0 12px rgba(232,133,12,0.2);
  border: 1px solid rgba(232,133,12,0.15);
}
.nav-brand .seo {
  background: var(--gold-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-shadow: none;
}
.nav-brand .baike {
  color: var(--text-primary);
  font-weight: 800;
  letter-spacing: 0.5px;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--sp-8);
  list-style: none;
}
.nav-links a {
  color: var(--text-muted);
  font-size: 0.88rem;
  font-weight: 500;
  letter-spacing: 0.3px;
  transition: color var(--duration-fast);
  position: relative;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
}
.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--gold-gradient);
  border-radius: 1px;
}
.nav-cta {
  padding: 8px 20px !important;
  border-radius: var(--radius-full) !important;
  background: var(--gold-gradient) !important;
  color: #000 !important;
  font-weight: 700 !important;
  font-size: 0.85rem !important;
  transition: all var(--duration-normal) var(--ease-out) !important;
  border: none;
}
.nav-cta:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-gold);
}

/* Hamburger */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}
.nav-hamburger span {
  width: 22px;
  height: 2px;
  background: var(--text-secondary);
  border-radius: 2px;
  transition: all var(--duration-normal) var(--ease-out);
}
.nav-hamburger.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.nav-hamburger.active span:nth-child(2) { opacity: 0; }
.nav-hamburger.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* Mobile Menu */
.mobile-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 999;
  background: rgba(6,6,15,0.97);
  backdrop-filter: blur(24px);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0;
  opacity: 0;
  transition: opacity var(--duration-normal) var(--ease-out);
}
.mobile-overlay.open {
  display: flex;
  opacity: 1;
}
.mobile-overlay a {
  display: block;
  padding: 16px 32px;
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-align: center;
  transition: color var(--duration-fast);
}
.mobile-overlay a:hover { color: var(--text-primary); }
.mobile-close {
  position: absolute;
  top: 16px;
  right: 20px;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 2rem;
  cursor: pointer;
  padding: 8px;
  line-height: 1;
}

/* ── Cards ── */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--sp-8);
  transition: all var(--duration-normal) var(--ease-out);
  position: relative;
  overflow: hidden;
}
.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 20%;
  right: 20%;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(232,133,12,0.2), transparent);
  opacity: 0;
  transition: opacity var(--duration-normal);
}
.card:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-gold);
}
.card:hover::before { opacity: 1; }

.card-glass {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--sp-8);
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-full);
  font-size: 0.92rem;
  font-weight: 700;
  font-family: var(--font-sans);
  cursor: pointer;
  transition: all var(--duration-normal) var(--ease-out);
  border: none;
  text-decoration: none;
  white-space: nowrap;
}
.btn-primary {
  background: var(--gold-gradient);
  color: #000;
  box-shadow: 0 2px 12px rgba(232,133,12,0.2);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 24px rgba(232,133,12,0.35);
  color: #000;
}
.btn-secondary {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-default);
}
.btn-secondary:hover {
  border-color: var(--border-hover);
  background: rgba(232,133,12,0.05);
  color: var(--text-primary);
}
.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  padding: 8px 16px;
}
.btn-ghost:hover { color: var(--text-primary); }

.btn-lg {
  padding: 16px 36px;
  font-size: 1rem;
}
.btn-sm {
  padding: 8px 18px;
  font-size: 0.82rem;
}

/* ── Inputs ── */
.input {
  width: 100%;
  padding: 12px 18px;
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.92rem;
  font-family: var(--font-sans);
  outline: none;
  transition: border-color var(--duration-fast), box-shadow var(--duration-fast);
}
.input:focus {
  border-color: var(--gold-300);
  box-shadow: 0 0 0 3px rgba(232,133,12,0.1);
}
.input::placeholder { color: var(--text-muted); }

textarea.input { resize: vertical; min-height: 100px; }

select.input {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg width='12' height='8' viewBox='0 0 12 8' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1.5L6 6.5L11 1.5' stroke='%236b6b8a' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
  padding-right: 36px;
}

/* ── Badge / Tag ── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}
.badge-gold {
  background: rgba(232,133,12,0.1);
  color: var(--gold-200);
  border: 1px solid rgba(232,133,12,0.2);
}
.badge-green {
  background: rgba(52,208,88,0.1);
  color: var(--success);
}
.badge-red {
  background: rgba(248,81,73,0.1);
  color: var(--danger);
}

/* ── Animations ── */
.fade-up {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}
.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}
@keyframes glow {
  0%, 100% { box-shadow: 0 0 0 0 rgba(232,133,12,0.3); }
  50% { box-shadow: 0 0 20px 4px rgba(232,133,12,0.15); }
}
@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}
@keyframes shimmer {
  0% { background-position: -200% center; }
  100% { background-position: 200% center; }
}

.animate-pulse { animation: pulse 2s ease-in-out infinite; }
.animate-glow { animation: glow 3s ease-in-out infinite; }
.animate-float { animation: float 4s ease-in-out infinite; }

/* ── Dividers ── */
.divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border-default), transparent);
  border: none;
  margin: var(--sp-16) 0;
}
.divider-gold {
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--gold-300), transparent);
}

/* ── Footer ── */
.footer {
  border-top: 1px solid var(--border-subtle);
  padding: var(--sp-16) 0 var(--sp-8);
  background: var(--bg-secondary);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: var(--sp-12);
  margin-bottom: var(--sp-12);
}
.footer-brand { display: flex; flex-direction: column; gap: var(--sp-4); }
.footer-brand p { font-size: 0.85rem; color: var(--text-muted); max-width: 280px; }
.footer-col h4 {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text-muted);
  letter-spacing: 1.5px;
  text-transform: uppercase;
  margin-bottom: var(--sp-4);
}
.footer-col a {
  display: block;
  color: var(--text-secondary);
  font-size: 0.88rem;
  padding: 4px 0;
  transition: color var(--duration-fast);
}
.footer-col a:hover { color: var(--text-primary); }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--sp-8);
  border-top: 1px solid var(--border-subtle);
  font-size: 0.78rem;
  color: var(--text-muted);
}
.footer-bottom a { color: var(--text-muted); }

/* ── Grid Utilities ── */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--sp-6); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--sp-6); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--sp-6); }

/* ── Utility ── */
.flex { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.flex-between { display: flex; align-items: center; justify-content: space-between; }
.gap-2 { gap: var(--sp-2); }
.gap-4 { gap: var(--sp-4); }
.gap-6 { gap: var(--sp-6); }
.gap-8 { gap: var(--sp-8); }
.text-center { text-align: center; }
.mx-auto { margin-left: auto; margin-right: auto; }
.mt-4 { margin-top: var(--sp-4); }
.mt-8 { margin-top: var(--sp-8); }
.mt-16 { margin-top: var(--sp-16); }
.mb-4 { margin-bottom: var(--sp-4); }
.mb-8 { margin-bottom: var(--sp-8); }

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-default); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* ── Touch ── */
* { -webkit-tap-highlight-color: transparent; }
select, button, a { touch-action: manipulation; }

/* ── Page Top Padding (for fixed nav) ── */
.page-top { padding-top: 64px; }

/* ═══════════ Responsive ═══════════ */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-hamburger { display: flex; }
  .nav { padding: 0 var(--sp-4); }
  .section { padding: var(--sp-16) 0; }
  .section-lg { padding: var(--sp-20) 0; }
  .container { padding: 0 var(--sp-4); }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: var(--sp-8); }
  .footer-bottom { flex-direction: column; gap: var(--sp-3); text-align: center; }
  .btn { min-height: 48px; font-size: 0.95rem; }
  body { font-size: 14px; }
  h1 { font-size: 1.8rem; }
  h2 { font-size: 1.5rem; }
  .section-header { margin-bottom: var(--sp-10); }
}
@media (max-width: 480px) {
  .btn { padding: 12px 20px; }
  .btn-lg { padding: 14px 28px; }
  .card { padding: var(--sp-5); }
  h1 { font-size: 1.5rem; }
}

/* ── Legal Disclaimer ── */
.footer-disclaimer {
  margin-top: var(--sp-4);
  padding-top: var(--sp-4);
  border-top: 1px solid var(--border-default);
  font-size: 0.7rem;
  color: var(--text-muted);
  line-height: 1.5;
  text-align: center;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
}

/* ── Scroll Observer Script Marker ── */
/* Add this JS to every page:
<script>
const obs = new IntersectionObserver((entries) => {
  entries.forEach(e => { if (e.isIntersecting) e.target.classList.add('visible'); });
}, { threshold: 0.08 });
document.querySelectorAll('.fade-up').forEach(el => obs.observe(el));

// Nav scroll
let lastScroll = 0;
window.addEventListener('scroll', () => {
  const nav = document.querySelector('.nav');
  if (nav) nav.classList.toggle('scrolled', window.scrollY > 20);
});

// Hamburger
function toggleMenu() {
  document.querySelector('.nav-hamburger')?.classList.toggle('active');
  document.querySelector('.mobile-overlay')?.classList.toggle('open');
}
</script>
*/