:root {
  --bg-dark: #0B1120;
  --bg-surface: #1E293B;
  --bg-card: rgba(30, 41, 59, 0.7);
  --bg-card-hover: rgba(51, 65, 85, 0.85);
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-emerald: rgba(16, 185, 129, 0.35);

  --emerald-primary: #10B981;
  --emerald-light: #34D399;
  --mint-teal: #14B8A6;
  --mint-glow: rgba(16, 185, 129, 0.25);

  --text-primary: #F8FAFC;
  --text-secondary: #CBD5E1;
  --text-muted: #94A3B8;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", Consolas, monospace;

  --transition-fast: 0.18s ease;
  --transition-normal: 0.25s ease;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background-color: var(--bg-dark);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Site Header */
.site-header {
  position: sticky;
  top: 0;
  width: 100%;
  height: 68px;
  background: rgba(11, 17, 32, 0.9);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-subtle);
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.brand-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-primary);
  flex-shrink: 0;
}

.brand-icon {
  width: 36px;
  height: 36px;
  transition: transform var(--transition-normal);
}
.brand-wrap:hover .brand-icon {
  transform: scale(1.06);
}

.brand-title-wrap {
  display: flex;
  flex-direction: column;
}
.brand-name {
  font-size: 1.15rem;
  font-weight: 800;
  color: #FFFFFF;
  display: flex;
  align-items: center;
  gap: 6px;
}
.help-badge {
  font-size: 0.62rem;
  font-family: var(--font-mono);
  background: rgba(16, 185, 129, 0.15);
  color: var(--emerald-light);
  border: 1px solid var(--border-emerald);
  padding: 1px 6px;
  border-radius: 4px;
}
.brand-sub {
  font-size: 0.68rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* Nav */
.desktop-nav {
  display: flex;
  align-items: center;
  gap: 6px;
  list-style: none;
}
.desktop-nav a {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  white-space: nowrap;
}
.desktop-nav a:hover {
  color: #FFFFFF;
  background: rgba(255, 255, 255, 0.06);
}
.desktop-nav a.active {
  color: var(--emerald-light);
  background: rgba(16, 185, 129, 0.12);
  border: 1px solid var(--border-emerald);
  font-weight: 600;
}

.btn-emerald-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 18px;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, #10B981 0%, #059669 100%);
  color: #FFFFFF;
  font-size: 0.85rem;
  font-weight: 700;
  text-decoration: none;
  transition: all var(--transition-normal);
  box-shadow: 0 4px 14px rgba(16, 185, 129, 0.35);
}
.btn-emerald-primary:hover {
  filter: brightness(1.1);
  transform: translateY(-1px);
}

.mobile-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--border-subtle);
  color: #FFFFFF;
  padding: 6px;
  border-radius: 6px;
  cursor: pointer;
}

/* Help Search Hero */
.help-hero {
  background: radial-gradient(circle at 50% 20%, rgba(16, 185, 129, 0.12) 0%, transparent 60%);
  padding: 65px 0 50px;
  text-align: center;
  border-bottom: 1px solid var(--border-subtle);
}
.help-hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  color: #FFFFFF;
  margin-bottom: 14px;
}
.help-hero p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 680px;
  margin: 0 auto 28px;
  line-height: 1.7;
}

.search-box-wrap {
  max-width: 620px;
  margin: 0 auto;
  position: relative;
}
.search-input {
  width: 100%;
  padding: 14px 20px 14px 48px;
  border-radius: 9999px;
  background: rgba(30, 41, 59, 0.8);
  border: 1px solid var(--border-emerald);
  color: #FFFFFF;
  font-size: 0.95rem;
  outline: none;
  transition: all var(--transition-fast);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
}
.search-input:focus {
  border-color: var(--emerald-light);
  box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.25);
  background: rgba(30, 41, 59, 1);
}
.search-icon {
  position: absolute;
  left: 18px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

/* Quick Categories Grid */
.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin: 40px 0;
}
.cat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-decoration: none;
  color: inherit;
  transition: all var(--transition-normal);
  display: flex;
  gap: 16px;
  align-items: flex-start;
}
.cat-card:hover {
  transform: translateY(-3px);
  border-color: var(--border-emerald);
  background: var(--bg-card-hover);
  box-shadow: 0 10px 25px rgba(16, 185, 129, 0.15);
}
.cat-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  background: rgba(16, 185, 129, 0.12);
  border: 1px solid var(--border-emerald);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  flex-shrink: 0;
}
.cat-content h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: #FFFFFF;
  margin-bottom: 6px;
}
.cat-content p {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* Accordion FAQ */
.faq-accordion {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin: 24px 0;
}
.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition-fast);
}
.faq-item:hover {
  border-color: var(--border-emerald);
}
.faq-header {
  padding: 16px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.98rem;
  color: #FFFFFF;
}
.faq-header:hover {
  color: var(--emerald-light);
}
.faq-body {
  padding: 0 20px 18px;
  color: var(--text-secondary);
  font-size: 0.92rem;
  line-height: 1.7;
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  padding-top: 14px;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border-subtle);
  background: #080D1A;
  padding: 50px 0 25px;
  margin-top: 60px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 36px;
  margin-bottom: 40px;
}
.footer-col h4 {
  font-size: 0.92rem;
  font-weight: 700;
  color: #FFFFFF;
  margin-bottom: 16px;
  text-transform: uppercase;
}
.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.footer-col a {
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.86rem;
  transition: color var(--transition-fast);
}
.footer-col a:hover {
  color: var(--emerald-light);
}
.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.8rem;
  color: var(--text-muted);
}

@media (max-width: 900px) {
  .desktop-nav { display: none; }
  .mobile-toggle { display: block; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .help-hero h1 { font-size: 2rem; }
}
@media (max-width: 600px) {
  .footer-grid { grid-template-columns: 1fr; }
  .help-hero h1 { font-size: 1.7rem; }
}