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

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

body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  background: #f5f7fb;
  color: #1a1f2b;
  line-height: 1.6;
  transition: background 0.3s, color 0.3s;
}

body.dark {
  background: #0b1320;
  color: #e3e8f0;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(11, 26, 46, 0.96);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15);
  transition: background 0.3s;
}

.dark .header {
  background: rgba(7, 16, 28, 0.96);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  padding: 0 20px;
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  font-size: 1.6rem;
  font-weight: 700;
  color: #f0c040;
  text-decoration: none;
  letter-spacing: 1px;
}

.logo span {
  color: #fff;
}

.nav {
  display: flex;
  gap: 24px;
  align-items: center;
}

.nav a {
  color: #eef2f8;
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  padding: 6px 0;
  border-bottom: 2px solid transparent;
  transition: border 0.2s, color 0.2s;
}

.nav a:hover {
  border-bottom-color: #f0c040;
  color: #f0c040;
}

.nav-toggle {
  display: none;
  background: transparent;
  border: 0;
  color: #fff;
  font-size: 1.8rem;
  cursor: pointer;
  padding: 4px 8px;
}

@media (max-width: 768px) {
  .nav {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: rgba(11, 26, 46, 0.98);
    padding: 20px;
    gap: 16px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
  }

  .nav.open {
    display: flex;
  }

  .nav-toggle {
    display: block;
  }
}

.hero {
  background: linear-gradient(145deg, #0b1a2e 0%, #1e3a5f 100%);
  color: #fff;
  padding: 80px 0 70px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::after {
  content: '';
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 200 200' opacity='0.08'%3E%3Ccircle cx='30' cy='40' r='20' fill='%23f0c040'/%3E%3Ccircle cx='170' cy='150' r='30' fill='%23f0c040'/%3E%3C/svg%3E") repeat;
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 2;
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 700;
  margin-bottom: 16px;
  letter-spacing: 1px;
}

.hero h1 em {
  color: #f0c040;
  font-style: normal;
}

.hero p {
  font-size: 1.2rem;
  max-width: 650px;
  margin: 0 auto 28px;
  color: #d0dbea;
}

.hero .btn-group {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 16px;
}

.btn {
  display: inline-block;
  padding: 14px 32px;
  border-radius: 50px;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.25s;
  background: #f0c040;
  color: #0b1a2e;
  box-shadow: 0 4px 12px rgba(240, 192, 64, 0.3);
}

.btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(240, 192, 64, 0.4);
}

.btn-outline {
  background: transparent;
  border: 2px solid #f0c040;
  color: #f0c040;
  box-shadow: none;
}

.btn-outline:hover {
  background: #f0c040;
  color: #0b1a2e;
}

.section {
  padding: 70px 0;
}

.section-title {
  font-size: 2rem;
  font-weight: 600;
  margin-bottom: 40px;
  text-align: center;
  position: relative;
}

.section-title:after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background: #f0c040;
  margin: 12px auto 0;
  border-radius: 4px;
}

.card {
  background: #fff;
  border-radius: 20px;
  padding: 28px;
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.06);
  transition: transform 0.2s, box-shadow 0.2s;
  border: 1px solid rgba(0, 0, 0, 0.03);
}

.dark .card {
  background: #162233;
  border-color: #2a3a52;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.1);
}

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
}

.grid-3 {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 28px;
}

@media (max-width: 768px) {
  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }
}

.text-center {
  text-align: center;
}

.mt-20 {
  margin-top: 20px;
}

.mb-20 {
  margin-bottom: 20px;
}

.badge {
  display: inline-block;
  background: rgba(240, 192, 64, 0.12);
  color: #f0c040;
  padding: 4px 14px;
  border-radius: 30px;
  font-size: 0.85rem;
  font-weight: 500;
}

.faq-item {
  border-bottom: 1px solid #e2e8f0;
  padding: 16px 0;
  cursor: pointer;
}

.dark .faq-item {
  border-color: #2a3a52;
}

.faq-question {
  font-weight: 600;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1.1rem;
}

.faq-question::after {
  content: '+';
  font-size: 1.6rem;
  font-weight: 300;
  transition: transform 0.3s;
}

.faq-item.open .faq-question::after {
  content: '−';
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease;
  color: #4a5568;
  padding-top: 0;
}

.dark .faq-answer {
  color: #b0c4de;
}

.faq-item.open .faq-answer {
  max-height: 300px;
  padding-top: 14px;
}

.footer {
  background: #0b1a2e;
  color: #b0c4de;
  padding: 40px 0;
  font-size: 0.95rem;
}

.footer a {
  color: #d0dbea;
  text-decoration: none;
}

.footer a:hover {
  color: #f0c040;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 32px;
}

@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.footer-bottom {
  border-top: 1px solid #1e3a5f;
  margin-top: 32px;
  padding-top: 20px;
  text-align: center;
  font-size: 0.85rem;
}

.scroll-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 46px;
  height: 46px;
  background: #f0c040;
  color: #0b1a2e;
  border: 0;
  border-radius: 50%;
  font-size: 1.6rem;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
  z-index: 99;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity 0.3s;
  opacity: 0;
  pointer-events: none;
}

.scroll-top.visible {
  opacity: 1;
  pointer-events: auto;
}

.dark .scroll-top {
  background: #f0c040;
  color: #0b1a2e;
}

.stat-number {
  font-size: 2.4rem;
  font-weight: 700;
  color: #f0c040;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

.knowledge-list {
  list-style: none;
  padding: 0;
}

.knowledge-list li {
  padding: 8px 0;
  border-bottom: 1px dashed #d0dbea;
  display: flex;
  gap: 8px;
}

.knowledge-list li::before {
  content: '▸';
  color: #f0c040;
}

.howto-step {
  display: flex;
  gap: 20px;
  margin-bottom: 24px;
  align-items: flex-start;
}

.howto-step .step-num {
  background: #f0c040;
  color: #0b1a2e;
  font-weight: 700;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.dark .howto-step .step-num {
  background: #f0c040;
  color: #0b1a2e;
}

.article-card time {
  color: #6b7a8f;
  font-size: 0.85rem;
}

.dark .article-card time {
  color: #8899b0;
}

.trust-badge {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin: 30px 0;
}

.trust-badge span {
  background: #e9edf4;
  padding: 8px 18px;
  border-radius: 30px;
  font-size: 0.9rem;
}

.dark .trust-badge span {
  background: #1e2d44;
  color: #d0dbea;
}

@media (prefers-color-scheme: dark) {
  body:not(.light) {
    background: #0b1320;
    color: #e3e8f0;
  }

  .card {
    background: #162233;
    border-color: #2a3a52;
  }

  .faq-answer {
    color: #b0c4de;
  }

  .trust-badge span {
    background: #1e2d44;
    color: #d0dbea;
  }

  .footer {
    background: #070f1a;
  }
}

a:focus-visible {
  outline: 2px solid #f0c040;
  outline-offset: 4px;
}

button:focus-visible {
  outline: 2px solid #f0c040;
}

.skip-link {
  position: absolute;
  top: -100px;
  left: 20px;
  background: #f0c040;
  color: #0b1a2e;
  padding: 12px 24px;
  z-index: 999;
  border-radius: 0 0 8px 8px;
  font-weight: 600;
}

.skip-link:focus {
  top: 0;
}

/* 滚动动画 */
.section {
  opacity: 0;
  transform: translateY(30px);
  animation: fadeInUp 0.6s ease forwards;
}

.section:nth-child(1) { animation-delay: 0.1s; }
.section:nth-child(2) { animation-delay: 0.2s; }
.section:nth-child(3) { animation-delay: 0.3s; }
.section:nth-child(4) { animation-delay: 0.4s; }
.section:nth-child(5) { animation-delay: 0.5s; }
.section:nth-child(6) { animation-delay: 0.6s; }
.section:nth-child(7) { animation-delay: 0.7s; }
.section:nth-child(8) { animation-delay: 0.8s; }

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* 毛玻璃效果增强 */
.header {
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

/* hover动画增强 */
.card {
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.12);
}

.dark .card:hover {
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.4);
}

.btn {
  transition: all 0.3s ease;
}

.btn:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 24px rgba(240, 192, 64, 0.5);
}

.btn-outline:hover {
  transform: translateY(-4px);
}

/* 响应式调整 */
@media (max-width: 480px) {
  .hero h1 {
    font-size: 2rem;
  }

  .hero p {
    font-size: 1rem;
  }

  .section-title {
    font-size: 1.6rem;
  }

  .card {
    padding: 20px;
  }
}