:root {
  --primary-color: #FF5136;
  --primary-hover: #E04027;
  --primary-light: #FFF4F2;
  --primary-gradient: linear-gradient(135deg, #FF7B60 0%, #FF5136 100%);
  --text-main: #1D1D1F;
  --text-secondary: #4A4A4F;
  --text-muted: #86868B;
  --bg-light: #F5F5F7;
  --bg-white: #FFFFFF;
  --border-color: #E2E2E7;
  --accent-blue: #0066CC;
  --accent-green: #24B354;
  --accent-gold: #FFB800;
  --card-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
  --card-shadow-hover: 0 16px 40px rgba(0, 0, 0, 0.08);
  --header-height: 72px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Microsoft YaHei", sans-serif;
  color: var(--text-main);
  background-color: var(--bg-white);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  text-decoration: none;
  color: inherit;
  transition: all 0.25s ease;
}

button, .btn {
  font-family: inherit;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 16px;
  padding: 12px 32px;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  transition: all 0.25s ease;
  outline: none;
}

/* 导航栏 */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  z-index: 1000;
}

.nav-container {
  max-width: 1200px;
  height: 100%;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  font-size: 20px;
  font-weight: 800;
  color: var(--text-main);
  gap: 10px;
}

.logo svg {
  width: 32px;
  height: 32px;
}

.nav-menu {
  display: flex;
  gap: 8px;
  list-style: none;
  align-items: center;
}

.nav-item a {
  display: block;
  padding: 8px 18px;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 500;
  color: var(--text-secondary);
}

.nav-item a:hover {
  color: var(--primary-color);
  background-color: rgba(255, 81, 54, 0.04);
}

.nav-item.active a {
  color: var(--primary-color);
  background-color: var(--primary-light);
  font-weight: 600;
}

.nav-download-btn {
  background: var(--primary-gradient);
  color: var(--bg-white);
  padding: 8px 18px;
  font-size: 14px;
  border-radius: 6px;
  font-weight: 600;
  box-shadow: 0 4px 12px rgba(255, 81, 54, 0.2);
}

.nav-download-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(255, 81, 54, 0.3);
}

/* 主容器 */
.main-content {
  margin-top: var(--header-height);
}

/* 通用布局与间隔 */
section {
  padding: 80px 24px;
}

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

.section-title {
  font-size: 36px;
  font-weight: 800;
  text-align: center;
  margin-bottom: 16px;
  letter-spacing: -0.5px;
  color: var(--text-main);
}

.section-subtitle {
  font-size: 18px;
  color: var(--text-secondary);
  text-align: center;
  max-width: 700px;
  margin: 0 auto 56px;
}

/* 按钮样式 */
.btn-primary {
  background: var(--primary-gradient);
  color: var(--bg-white);
  box-shadow: 0 8px 24px rgba(255, 81, 54, 0.25);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(255, 81, 54, 0.35);
}

.btn-secondary {
  background-color: var(--bg-light);
  color: var(--text-main);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  background-color: var(--border-color);
  transform: translateY(-1px);
}

.btn-outline {
  background-color: transparent;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
}

.btn-outline:hover {
  background-color: var(--primary-light);
  transform: translateY(-1px);
}

/* 页脚样式 */
.footer {
  background-color: #121214;
  color: #A1A1A6;
  padding: 64px 24px 32px;
  font-size: 14px;
  border-top: 1px solid #2C2C2E;
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.footer-safety {
  display: flex;
  align-items: center;
  gap: 8px;
  background-color: rgba(36, 179, 84, 0.1);
  color: #24B354;
  padding: 10px 24px;
  border-radius: 30px;
  font-weight: 600;
  margin-bottom: 24px;
  border: 1px solid rgba(36, 179, 84, 0.2);
}

.footer-safety svg {
  width: 18px;
  height: 18px;
}

.footer-warning {
  max-width: 800px;
  margin-bottom: 24px;
  line-height: 1.8;
  color: #86868B;
}

.footer-copyright {
  border-top: 1px solid #2C2C2E;
  padding-top: 24px;
  width: 100%;
  color: #636366;
  font-size: 13px;
}

/* 旋转动画 */
@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* 按钮禁用状态 */
button:disabled, .btn:disabled {
  opacity: 0.8 !important;
  cursor: not-allowed !important;
  transform: none !important;
  box-shadow: none !important;
}

/* 常见问题 Accordion */
.faq-grid {
  max-width: 850px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-card {
  border: 1px solid var(--border-color);
  border-radius: 12px;
  background-color: var(--bg-white);
  overflow: hidden;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.faq-card:hover {
  border-color: rgba(255, 81, 54, 0.4);
  box-shadow: 0 4px 12px rgba(0,0,0,0.02);
}

.faq-card details {
  width: 100%;
}

.faq-card summary {
  padding: 20px 24px;
  font-weight: 600;
  font-size: 17px;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text-main);
  outline: none;
  user-select: none;
}

.faq-card summary::-webkit-details-marker {
  display: none;
}

.faq-card summary::after {
  content: "";
  display: inline-block;
  width: 12px;
  height: 12px;
  border-right: 2px solid var(--text-secondary);
  border-bottom: 2px solid var(--text-secondary);
  transform: rotate(45deg);
  transition: transform 0.25s ease;
  margin-right: 4px;
  flex-shrink: 0;
}

.faq-card details[open] summary::after {
  transform: rotate(-135deg);
}

.faq-card details[open] summary {
  border-bottom: 1px solid var(--border-color);
  color: var(--primary-color);
}

.faq-answer {
  padding: 20px 24px;
  color: var(--text-secondary);
  font-size: 15px;
  background-color: rgba(0, 0, 0, 0.01);
  line-height: 1.7;
}

/* 响应式调整 */
@media (max-width: 768px) {
  .section-title {
    font-size: 28px;
  }
  .section-subtitle {
    font-size: 16px;
    margin-bottom: 36px;
  }
  .nav-menu {
    gap: 4px;
  }
  .nav-item a {
    padding: 6px 10px;
    font-size: 13px;
  }
  .nav-download-btn {
    display: none; /* 移动端隐藏导航栏下载，让出空间 */
  }
  section {
    padding: 50px 16px;
  }
}