/* ========== 基础样式（与首页一致） ========== */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; }
body { font-family: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif; color: #0F172A; background: #F8FAFC; line-height: 1.6; overflow-x: hidden; }
:root {
  --primary: #0EA5E9; --primary-dark: #0284C7; --primary-light: #38BDF8;
  --accent: #10B981; --success: #10B981; --warning: #F59E0B;
  --bg: #F8FAFC; --card-bg: #FFFFFF; --text: #0F172A; --text-secondary: #475569;
  --border: #E2E8F0; --radius: 16px; --shadow: 0 1px 3px rgba(0,0,0,0.08); --shadow-lg: 0 10px 40px rgba(0,0,0,0.1);
  --gradient: linear-gradient(135deg, #0EA5E9, #10B981);
  --gradient-light: linear-gradient(135deg, #38BDF8, #34D399);
}
a { text-decoration: none; }

.progress-bar { position: fixed; top: 0; left: 0; height: 3px; background: var(--gradient); z-index: 10001; transition: width 0.2s; width: 0; }
.header { position: fixed; top: 0; left: 0; right: 0; z-index: 10000; padding: 12px 0; transition: all 0.3s; }
.header.scrolled { background: rgba(255,255,255,0.85); backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px); box-shadow: 0 1px 3px rgba(0,0,0,0.08); border-bottom: 1px solid rgba(226,232,240,0.6); }
.header-inner { max-width: 1280px; margin: 0 auto; padding: 0 24px; display: flex; align-items: center; justify-content: space-between; }
.logo { display: flex; align-items: center; gap: 10px; text-decoration: none; font-size: 22px; font-weight: 700; color: var(--text); }
.logo img { height: 36px; width: auto; }
.nav { display: flex; align-items: center; gap: 26px; list-style: none; }
.nav a { text-decoration: none; color: var(--text-secondary); font-size: 15px; font-weight: 500; transition: color 0.2s; white-space: nowrap; }
.nav a:hover { color: var(--primary); }
.nav-cta { display: flex; align-items: center; gap: 12px; }
.btn { display: inline-flex; align-items: center; justify-content: center; padding: 10px 20px; border-radius: 8px; font-size: 15px; font-weight: 600; text-decoration: none; cursor: pointer; border: none; transition: all 0.2s; white-space: nowrap; }
.btn-primary { background: var(--gradient); color: #fff; box-shadow: 0 4px 15px rgba(14,165,233,0.35); }
.btn-primary:hover { transform: translateY(-2px) scale(1.02); box-shadow: 0 6px 25px rgba(14,165,233,0.5); }
.btn-outline { border: 2px solid var(--primary); color: var(--primary); background: transparent; }
.btn-outline:hover { background: var(--primary); color: #fff; }
.btn-warning { background: linear-gradient(135deg, #F59E0B, #F97316); color: #fff; box-shadow: 0 4px 15px rgba(245,158,11,0.4); }
.btn-warning:hover { transform: translateY(-2px) scale(1.02); box-shadow: 0 8px 28px rgba(245,158,11,0.55); }
.btn-lg { padding: 16px 36px; font-size: 18px; border-radius: 12px; }
.btn-xl { padding: 20px 48px; font-size: 20px; border-radius: 14px; }
.hamburger { display: none; flex-direction: column; gap: 5px; cursor: pointer; background: none; border: none; padding: 8px; }
.hamburger span { display: block; width: 24px; height: 2px; background: var(--text); border-radius: 2px; transition: all 0.3s; }

.section { padding: 90px 24px; }
.section-inner { max-width: 1280px; margin: 0 auto; }
.section-label { text-align: center; font-size: 14px; font-weight: 600; color: var(--primary); text-transform: uppercase; letter-spacing: 2px; margin-bottom: 12px; }
.section-title { text-align: center; font-size: clamp(28px, 3.5vw, 40px); font-weight: 800; margin-bottom: 16px; color: var(--text); }
.section-desc { text-align: center; font-size: 18px; color: var(--text-secondary); max-width: 640px; margin: 0 auto 50px; }

/* ========== 支持中心特有样式 ========== */
.hero-help {
  min-height: 70vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding-top: 100px;
  background: radial-gradient(ellipse at 30% 40%, rgba(14,165,233,0.12) 0%, transparent 65%), radial-gradient(ellipse at 70% 30%, rgba(16,185,129,0.1) 0%, transparent 65%);
}
.hero-help-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 60px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}
.hero-help h1 {
  font-size: clamp(32px, 4.5vw, 52px);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-help .subtitle {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 700px;
  margin-bottom: 28px;
}
.hero-help .hero-actions { display: flex; gap: 16px; flex-wrap: wrap; justify-content: center; }

.search-box {
  width: 100%;
  max-width: 600px;
  display: flex;
  gap: 10px;
  margin: 20px auto 0;
}
.search-box input {
  flex: 1;
  padding: 14px 20px;
  border-radius: 12px;
  border: 2px solid var(--border);
  font-size: 16px;
  outline: none;
  transition: border-color 0.3s;
}
.search-box input:focus { border-color: var(--primary); }
.search-box button {
  padding: 14px 30px;
  border-radius: 12px;
  border: none;
  background: var(--gradient);
  color: #fff;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
}
.search-box button:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(14,165,233,0.4); }

.category-nav {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}
.category-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  transition: all 0.3s;
}
.category-card:hover { transform: translateY(-5px); box-shadow: var(--shadow-lg); border-color: var(--primary-light); }
.category-card .cat-icon { font-size: 36px; margin-bottom: 10px; }
.category-card h3 { font-size: 16px; font-weight: 700; color: var(--text); }
.category-card .cat-count { font-size: 12px; color: var(--text-secondary); margin-top: 4px; }

.troubleshoot-steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.ts-step {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 28px 20px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  text-align: center;
  position: relative;
}
.ts-step .step-num {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--gradient);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  margin: 0 auto 16px;
}
.ts-step h3 { font-size: 18px; font-weight: 700; margin-bottom: 8px; }
.ts-step p { font-size: 14px; color: var(--text-secondary); line-height: 1.6; }

.faq-section { max-width: 900px; margin: 0 auto; }
.faq-category { margin-bottom: 40px; }
.faq-cat-title { font-size: 22px; font-weight: 700; margin-bottom: 16px; color: var(--text); padding-bottom: 10px; border-bottom: 3px solid var(--primary-light); display: flex; align-items: center; gap: 10px; }
.faq-item { background: var(--card-bg); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 12px; overflow: hidden; }
.faq-q { padding: 18px 20px; font-size: 16px; font-weight: 600; cursor: pointer; display: flex; justify-content: space-between; align-items: center; transition: all 0.2s; }
.faq-q:hover { color: var(--primary); }
.faq-q .arrow { transition: transform 0.3s; font-size: 12px; }
.faq-q.open .arrow { transform: rotate(180deg); }
.faq-a { padding: 0 20px; max-height: 0; overflow: hidden; transition: all 0.3s; color: var(--text-secondary); font-size: 15px; line-height: 1.8; }
.faq-a.open { padding: 0 20px 20px; max-height: 1200px; }
.faq-a .step { display: flex; gap: 10px; margin-bottom: 8px; }
.faq-a .step-num { font-weight: 700; color: var(--primary); min-width: 24px; }
.faq-a p { margin-bottom: 10px; }

.tip-box {
  background: #F0FDF4;
  border-left: 4px solid var(--success);
  padding: 16px 20px;
  border-radius: 8px;
  margin: 16px 0;
  font-size: 14px;
  color: #166534;
}

.diagnostic-box {
  background: linear-gradient(135deg, #0F172A, #1E293B);
  border-radius: var(--radius);
  padding: 40px;
  color: #fff;
  text-align: center;
}
.diagnostic-box h3 { font-size: 24px; font-weight: 700; margin-bottom: 20px; }
.diagnostic-box .diag-buttons { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.diagnostic-box .diag-btn {
  padding: 12px 24px;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  font-size: 15px;
  font-weight: 600;
  transition: all 0.3s;
}
.diagnostic-box .diag-btn.dark { background: rgba(255,255,255,0.1); color: #fff; }
.diagnostic-box .diag-btn.dark:hover { background: rgba(255,255,255,0.2); }
.diagnostic-box .diag-result { margin-top: 20px; font-size: 16px; }

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.stat-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  transition: all 0.3s;
}
.stat-card:hover { transform: translateY(-5px); box-shadow: var(--shadow-lg); }
.stat-card .stat-icon { font-size: 32px; margin-bottom: 10px; }
.stat-card .stat-num { font-size: 36px; font-weight: 800; color: var(--primary); }
.stat-card .stat-label { font-size: 14px; color: var(--text-secondary); margin-top: 6px; }

.contact-banner {
  background: var(--gradient);
  border-radius: var(--radius);
  padding: 40px;
  color: #fff;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}
.contact-banner h3 { font-size: 26px; font-weight: 800; }
.contact-banner p { font-size: 16px; opacity: 0.9; max-width: 600px; }
.contact-banner .btn-white { background: #fff; color: var(--primary); }

.footer { background: #0F172A; color: #CBD5E1; padding: 60px 24px 30px; }
.footer-inner { max-width: 1280px; margin: 0 auto; display: grid; grid-template-columns: 2fr 1fr 1fr 1fr 1.5fr; gap: 40px; }
.footer h4 { color: #fff; font-size: 15px; font-weight: 700; margin-bottom: 16px; }
.footer a { color: #94A3B8; text-decoration: none; font-size: 14px; display: block; margin-bottom: 8px; transition: color 0.2s; }
.footer a:hover { color: #fff; }
.footer-brand p { font-size: 14px; line-height: 1.7; margin: 12px 0; }
.footer-brand .footer-logo { display: flex; align-items: center; gap: 10px; }
.footer-brand .footer-logo img { height: 32px; }
.footer-brand .footer-logo span { color: #fff; font-size: 20px; font-weight: 700; }
.footer-warning { margin-top: 18px; padding: 12px 16px; background: rgba(245,158,11,0.15); border: 1px solid rgba(245,158,11,0.3); border-radius: 8px; font-size: 13px; color: #FCD34D; line-height: 1.6; }
.footer-bottom { max-width: 1280px; margin: 40px auto 0; padding-top: 24px; border-top: 1px solid rgba(255,255,255,0.1); text-align: center; font-size: 13px; color: #64748B; }
.footer-bottom a { color: #94A3B8; display: inline; }
.friend-links { margin-top: 20px; padding: 16px 0; text-align: center; }
.friend-links a { display: inline !important; margin: 0 8px; }

@media (max-width: 1024px) {
  .category-nav, .troubleshoot-steps, .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-inner { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 768px) {
  .nav { display: none; flex-direction: column; position: absolute; top: 100%; left: 0; right: 0; background: rgba(255,255,255,0.97); backdrop-filter: blur(20px); padding: 20px; gap: 16px; border-bottom: 1px solid var(--border); }
  .nav.open { display: flex; }
  .hamburger { display: flex; }
  .nav-cta { display: none; }
  .category-nav, .troubleshoot-steps, .stats-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr 1fr; }
  .hero-help .hero-actions { flex-direction: column; }
  .search-box { flex-direction: column; }
}