/* GEO 优化公司官网 - 样式文件 */
/* 设计参考：Vercel Design System + 企业级白色系风格 */

/* ========================================
   1. CSS 变量与设计系统
   ======================================== */
:root {
  /* 色彩系统 */
  --color-primary: #ffffff;
  --color-secondary: #f9fafb;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-text-primary: #1f2937;
  --color-text-secondary: #6b7280;
  --color-border: #e5e7eb;
  --color-nav-bg: #ffffff;
  --color-nav-shadow: rgba(0, 0, 0, 0.05);

  /* Vercel 风格阴影系统 */
  --shadow-ring: 0px 0px 0px 1px rgba(0, 0, 0, 0.08);
  --shadow-subtle: 0px 0px 0px 1px rgba(0, 0, 0, 0.08), rgba(0, 0, 0, 0.04) 0px 2px 2px;
  --shadow-card: 0px 0px 0px 1px rgba(0, 0, 0, 0.08), rgba(0, 0, 0, 0.04) 0px 2px 2px, #fafafa 0px 0px 0px 1px;
  --shadow-elevated: 0px 0px 0px 1px rgba(0, 0, 0, 0.08), rgba(0, 0, 0, 0.04) 0px 8px 8px -8px;

  /* 字体系统 */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'SF Mono', 'Consolas', 'Monaco', monospace;

  /* 间距系统 */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  --spacing-3xl: 64px;
  --spacing-4xl: 80px;

  /* 圆角系统 */
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-xl: 12px;
  --radius-full: 9999px;

  /* 过渡 */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

/* ========================================
   2. 基础重置与全局样式
   ======================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text-primary);
  background-color: var(--color-primary);
  min-height: 100vh;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent-hover);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

/* ========================================
   3. 排版规范
   ======================================== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  color: var(--color-text-primary);
}

h1 {
  font-size: 40px;
  letter-spacing: -1.6px;
}

h2 {
  font-size: 32px;
  letter-spacing: -1.28px;
}

h3 {
  font-size: 24px;
  letter-spacing: -0.96px;
}

h4 {
  font-size: 18px;
  letter-spacing: -0.72px;
}

p {
  color: var(--color-text-secondary);
  line-height: 1.75;
}

.text-large {
  font-size: 20px;
  line-height: 1.8;
}

.text-small {
  font-size: 14px;
}

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

.section-title {
  font-size: 32px;
  letter-spacing: -1.28px;
  margin-bottom: var(--spacing-md);
}

.section-subtitle {
  font-size: 18px;
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ========================================
   4. 布局容器
   ======================================== */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-3xl);
}

.section {
  padding: var(--spacing-4xl) 0;
}

.section-header {
  text-align: center;
  margin-bottom: var(--spacing-3xl);
}

.section-header h2 {
  margin-bottom: var(--spacing-md);
}

.grid {
  display: grid;
  gap: var(--spacing-lg);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr);
}

/* ========================================
   5. 导航栏
   ======================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 64px;
  background: var(--color-nav-bg);
  box-shadow: var(--shadow-ring);
  z-index: 1000;
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  padding: 0 var(--spacing-3xl);
}

.navbar-logo {
  font-size: 20px;
  font-weight: 600;
  color: var(--color-text-primary);
  letter-spacing: -0.8px;
}

.navbar-logo span {
  color: var(--color-accent);
}

.navbar-menu {
  display: flex;
  align-items: center;
  gap: var(--spacing-xl);
}

.navbar-menu a {
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text-primary);
  padding: var(--spacing-sm) 0;
  position: relative;
}

.navbar-menu a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width var(--transition-fast);
}

.navbar-menu a:hover::after,
.navbar-menu a.active::after {
  width: 100%;
}

.navbar-menu a:hover {
  color: var(--color-text-primary);
}

.navbar-cta {
  margin-left: var(--spacing-lg);
}

/* 移动端菜单按钮 */
.navbar-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
}

.navbar-toggle svg {
  width: 24px;
  height: 24px;
  stroke: var(--color-text-primary);
}

/* ========================================
   6. 按钮组件
   ======================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 44px;
  padding: 0 var(--spacing-lg);
  font-size: 15px;
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn-primary {
  background: var(--color-accent);
  color: #ffffff;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  color: #ffffff;
}

.btn-secondary {
  background: var(--color-primary);
  color: var(--color-text-primary);
  box-shadow: var(--shadow-ring);
}

.btn-secondary:hover {
  background: var(--color-secondary);
  color: var(--color-text-primary);
}

.btn-dark {
  background: var(--color-text-primary);
  color: #ffffff;
}

.btn-dark:hover {
  background: #000000;
  color: #ffffff;
}

.btn-lg {
  height: 52px;
  padding: 0 var(--spacing-xl);
  font-size: 16px;
}

.btn svg {
  width: 18px;
  height: 18px;
  margin-right: var(--spacing-sm);
}

/* ========================================
   7. 卡片组件
   ======================================== */
.card {
  background: var(--color-primary);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  padding: var(--spacing-lg);
  transition: all var(--transition-normal);
}

.card:hover {
  box-shadow: var(--shadow-elevated);
  transform: translateY(-2px);
}

.card-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-secondary);
  border-radius: var(--radius-lg);
  margin-bottom: var(--spacing-md);
}

.card-icon svg {
  width: 24px;
  height: 24px;
  stroke: var(--color-accent);
}

.card-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  letter-spacing: -0.72px;
}

.card-text {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.card-link {
  display: inline-flex;
  align-items: center;
  margin-top: var(--spacing-md);
  font-size: 14px;
  font-weight: 500;
  color: var(--color-accent);
}

.card-link svg {
  width: 16px;
  height: 16px;
  margin-left: var(--spacing-xs);
  transition: transform var(--transition-fast);
}

.card-link:hover svg {
  transform: translateX(4px);
}

/* ========================================
   8. Hero 区域
   ======================================== */
.hero {
  padding: 160px 0 100px;
  text-align: center;
  background: linear-gradient(180deg, var(--color-secondary) 0%, var(--color-primary) 100%);
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 48px;
  letter-spacing: -2.4px;
  line-height: 1.1;
  margin-bottom: var(--spacing-lg);
}

.hero-subtitle {
  font-size: 20px;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: var(--spacing-xl);
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
}

.hero-buttons {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
}

/* ========================================
   9. 页面标题区
   ======================================== */
.page-header {
  padding: 140px 0 60px;
  text-align: center;
  background: var(--color-secondary);
}

.page-header h1 {
  margin-bottom: var(--spacing-md);
}

.page-header p {
  font-size: 18px;
  max-width: 600px;
  margin: 0 auto;
}

/* ========================================
   10. 特色区块
   ======================================== */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-lg);
}

.feature-item {
  text-align: center;
  padding: var(--spacing-xl);
}

.feature-icon {
  width: 64px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-secondary);
  border-radius: var(--radius-xl);
  margin: 0 auto var(--spacing-lg);
}

.feature-icon svg {
  width: 32px;
  height: 32px;
  stroke: var(--color-accent);
}

.feature-item h3 {
  font-size: 18px;
  margin-bottom: var(--spacing-sm);
}

.feature-item p {
  font-size: 15px;
}

/* ========================================
   11. 价格卡片
   ======================================== */
.pricing-card {
  max-width: 480px;
  margin: 0 auto;
  padding: var(--spacing-2xl);
  text-align: center;
  box-shadow: var(--shadow-card);
  border-radius: var(--radius-xl);
}

.pricing-price {
  font-size: 56px;
  font-weight: 600;
  color: var(--color-text-primary);
  letter-spacing: -2.24px;
}

.pricing-price span {
  font-size: 20px;
  font-weight: 400;
  color: var(--color-text-secondary);
}

.pricing-features {
  margin: var(--spacing-lg) 0;
  padding: var(--spacing-lg) 0;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.pricing-features li {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) 0;
  font-size: 15px;
  color: var(--color-text-secondary);
}

.pricing-features svg {
  width: 18px;
  height: 18px;
  stroke: var(--color-accent);
}

/* ========================================
   12. CTA 横幅
   ======================================== */
.cta-section {
  background: var(--color-secondary);
  padding: var(--spacing-4xl) 0;
  text-align: center;
}

.cta-section h2 {
  margin-bottom: var(--spacing-lg);
}

.cta-section p {
  font-size: 18px;
  margin-bottom: var(--spacing-xl);
}

/* ========================================
   13. FAQ 手风琴
   ======================================== */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
}

.faq-question {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-lg) 0;
  font-size: 16px;
  font-weight: 500;
  color: var(--color-text-primary);
  text-align: left;
  cursor: pointer;
}

.faq-question svg {
  width: 20px;
  height: 20px;
  stroke: var(--color-text-secondary);
  transition: transform var(--transition-fast);
}

.faq-item.active .faq-question svg {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-normal);
}

.faq-item.active .faq-answer {
  max-height: 300px;
}

.faq-answer p {
  padding-bottom: var(--spacing-lg);
  font-size: 15px;
}

/* ========================================
   14. 时间线 / 流程
   ======================================== */
.timeline {
  position: relative;
  padding-left: var(--spacing-3xl);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 11px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--color-border);
}

.timeline-item {
  position: relative;
  padding-bottom: var(--spacing-2xl);
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: calc(-1 * var(--spacing-3xl) + 4px);
  width: 16px;
  height: 16px;
  background: var(--color-accent);
  border-radius: 50%;
  border: 3px solid var(--color-primary);
}

.timeline-content h4 {
  margin-bottom: var(--spacing-sm);
}

.timeline-content p {
  font-size: 15px;
}

.timeline-meta {
  display: inline-block;
  margin-top: var(--spacing-sm);
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--color-secondary);
  border-radius: var(--radius-sm);
  font-size: 13px;
  color: var(--color-text-secondary);
}

/* ========================================
   15. 步骤流程图
   ======================================== */
.process-steps {
  display: flex;
  justify-content: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-3xl);
  flex-wrap: wrap;
}

.process-step {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.step-number {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-accent);
  color: #ffffff;
  border-radius: 50%;
  font-size: 14px;
  font-weight: 600;
}

.step-label {
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-primary);
}

.step-arrow {
  width: 24px;
  height: 24px;
  stroke: var(--color-border);
}

.process-flow {
  display: flex;
  justify-content: center;
  gap: var(--spacing-xl);
  flex-wrap: wrap;
}

.process-card {
  width: 200px;
  padding: var(--spacing-lg);
  text-align: center;
  box-shadow: var(--shadow-card);
  border-radius: var(--radius-lg);
}

.process-card h4 {
  margin: var(--spacing-md) 0 var(--spacing-sm);
}

.process-card p {
  font-size: 14px;
}

/* ========================================
   16. 联系信息
   ======================================== */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-lg);
}

.contact-card {
  padding: var(--spacing-xl);
  text-align: center;
  box-shadow: var(--shadow-card);
  border-radius: var(--radius-lg);
}

.contact-icon {
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-secondary);
  border-radius: var(--radius-xl);
  margin: 0 auto var(--spacing-md);
}

.contact-icon svg {
  width: 28px;
  height: 28px;
  stroke: var(--color-accent);
}

.contact-card h4 {
  margin-bottom: var(--spacing-sm);
}

.contact-card p {
  font-size: 15px;
}

.contact-value {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-sm);
}

.qr-code {
  width: 120px;
  height: 120px;
  margin: var(--spacing-md) auto 0;
  border-radius: var(--radius-md);
  overflow: hidden;
}

.qr-code img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ========================================
   17. 联系表单
   ======================================== */
.contact-form {
  max-width: 600px;
  margin: 0 auto;
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-card);
  border-radius: var(--radius-xl);
}

.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-primary);
}

.form-group label span {
  color: #ef4444;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: var(--spacing-md);
  font-size: 15px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-primary);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-group textarea {
  min-height: 120px;
  resize: vertical;
}

.form-row {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-lg);
}

/* ========================================
   18. 列表样式
   ======================================== */
.list-check li {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) 0;
}

.list-check li svg {
  width: 20px;
  height: 20px;
  stroke: var(--color-accent);
  flex-shrink: 0;
  margin-top: 2px;
}

/* ========================================
   19. 服务模块
   ======================================== */
.service-module {
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-card);
  border-radius: var(--radius-xl);
  margin-bottom: var(--spacing-lg);
}

.service-module h3 {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}

.service-module h3 svg {
  width: 24px;
  height: 24px;
  stroke: var(--color-accent);
}

.service-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-sm) var(--spacing-xl);
}

.service-list li {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 15px;
  color: var(--color-text-secondary);
}

.service-list li svg {
  width: 16px;
  height: 16px;
  stroke: var(--color-accent);
  flex-shrink: 0;
}

.service-deliverable {
  margin-top: var(--spacing-md);
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border);
  font-size: 14px;
  color: var(--color-text-secondary);
}

.service-deliverable strong {
  color: var(--color-text-primary);
}

/* ========================================
   20. 页脚
   ======================================== */
.footer {
  background: var(--color-secondary);
  padding: var(--spacing-3xl) 0;
  margin-top: var(--spacing-4xl);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--spacing-xl);
}

.footer-brand {
  max-width: 300px;
}

.footer-brand h3 {
  font-size: 18px;
  margin-bottom: var(--spacing-md);
}

.footer-brand p {
  font-size: 14px;
}

.footer-links h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--color-text-primary);
}

.footer-links ul {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.footer-links a {
  font-size: 14px;
  color: var(--color-text-secondary);
}

.footer-links a:hover {
  color: var(--color-text-primary);
}

.footer-bottom {
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 14px;
  color: var(--color-text-secondary);
}

.footer-contact p {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-sm);
  font-size: 14px;
  color: var(--color-text-secondary);
}

.footer-contact svg {
  width: 16px;
  height: 16px;
  stroke: var(--color-text-secondary);
}

/* ========================================
   21. 模态框
   ======================================== */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
}

.modal.active {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: var(--color-primary);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  max-width: 320px;
  text-align: center;
  transform: scale(0.9);
  transition: transform var(--transition-normal);
}

.modal.active .modal-content {
  transform: scale(1);
}

.modal-close {
  position: absolute;
  top: var(--spacing-md);
  right: var(--spacing-md);
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--color-secondary);
}

.modal-close svg {
  width: 20px;
  height: 20px;
  stroke: var(--color-text-secondary);
}

.modal-qr {
  width: 200px;
  height: 200px;
  margin: var(--spacing-lg) auto;
  border-radius: var(--radius-md);
  overflow: hidden;
}

.modal-qr img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ========================================
   22. 响应式设计
   ======================================== */
@media (max-width: 1024px) {
  .container {
    padding: 0 var(--spacing-xl);
  }

  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }

  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .contact-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --spacing-4xl: 60px;
    --spacing-3xl: 40px;
  }

  h1 {
    font-size: 32px;
    letter-spacing: -1.28px;
  }

  h2 {
    font-size: 26px;
    letter-spacing: -1.04px;
  }

  h3 {
    font-size: 20px;
    letter-spacing: -0.8px;
  }

  .hero {
    padding: 120px 0 60px;
  }

  .hero h1 {
    font-size: 32px;
    letter-spacing: -1.28px;
  }

  .hero-subtitle {
    font-size: 18px;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .navbar .container {
    padding: 0 var(--spacing-lg);
  }

  .navbar-menu {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--color-primary);
    flex-direction: column;
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-ring);
    gap: var(--spacing-md);
  }

  .navbar-menu.active {
    display: flex;
  }

  .navbar-cta {
    margin-left: 0;
    width: 100%;
  }

  .navbar-cta .btn {
    width: 100%;
  }

  .navbar-toggle {
    display: flex;
  }

  .grid-2,
  .grid-3,
  .grid-4,
  .feature-grid {
    grid-template-columns: 1fr;
  }

  .contact-grid {
    grid-template-columns: 1fr;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .service-list {
    grid-template-columns: 1fr;
  }

  .footer-content {
    flex-direction: column;
    text-align: center;
  }

  .footer-bottom {
    flex-direction: column;
    gap: var(--spacing-md);
  }

  .process-steps {
    flex-direction: column;
    align-items: center;
  }

  .process-flow {
    flex-direction: column;
    align-items: center;
  }

  .process-card {
    width: 100%;
    max-width: 300px;
  }

  .pricing-price {
    font-size: 42px;
  }
}

@media (max-width: 480px) {
  .section {
    padding: var(--spacing-3xl) 0;
  }

  .card {
    padding: var(--spacing-md);
  }

  .page-header {
    padding: 120px 0 40px;
  }
}

/* ========================================
   23. 动画效果
   ======================================== */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeIn 0.6s ease forwards;
}

.fade-in-delay-1 { animation-delay: 0.1s; }
.fade-in-delay-2 { animation-delay: 0.2s; }
.fade-in-delay-3 { animation-delay: 0.3s; }
.fade-in-delay-4 { animation-delay: 0.4s; }

/* ========================================
   24. 工具类
   ======================================== */
.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }
.mt-2xl { margin-top: var(--spacing-2xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }
.mb-2xl { margin-bottom: var(--spacing-2xl); }

.hidden { display: none !important; }