/* 基础样式 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  line-height: 1.8;
  transition: all 0.3s ease;
  min-height: 100vh;
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 40px;
}

/* 头部样式 */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 30px 0;
  transition: all 0.3s ease;
  border-bottom: 1px solid transparent;
}

.title {
  font-size: 32px;
  font-weight: 700;
  letter-spacing: -0.5px;
  transition: all 0.3s ease;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.theme-toggle {
  padding: 12px 24px;
  border: none;
  border-radius: 50px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.theme-toggle:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

/* 导航栏样式 */
.nav {
  margin: 40px 0;
  border-radius: 16px;
  overflow: hidden;
  transition: all 0.3s ease;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

.nav-list {
  display: flex;
  list-style: none;
}

.nav-item {
  flex: 1;
  text-align: center;
  padding: 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 500;
  font-size: 16px;
  position: relative;
}

.nav-item::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0;
  height: 3px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  transition: all 0.3s ease;
  transform: translateX(-50%);
}

.nav-item:hover::after {
  width: 60%;
}

.nav-item.active::after {
  width: 60%;
}

/* 内容区域样式 */
.content {
  min-height: 500px;
  padding-bottom: 60px;
}

.section {
  display: none;
  padding: 40px;
  border-radius: 20px;
  transition: all 0.3s ease;
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.06);
}

.section.active {
  display: block;
  animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.section-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 30px;
}

.card {
  padding: 30px;
  border-radius: 16px;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
  box-shadow: 0 2px 15px rgba(0, 0, 0, 0.05);
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  transform: scaleX(0);
  transition: all 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
}

.card:hover::before {
  transform: scaleX(1);
}

.card h3 {
  margin-bottom: 20px;
  font-size: 20px;
  font-weight: 600;
  transition: all 0.3s ease;
  position: relative;
  padding-bottom: 10px;
}

.card h3::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 40px;
  height: 2px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.card ul {
  list-style: none;
}

.card li {
  margin-bottom: 12px;
  padding-left: 30px;
  position: relative;
  transition: all 0.3s ease;
  font-size: 15px;
  line-height: 1.8;
}

.card li::before {
  content: '✓';
  position: absolute;
  left: 0;
  font-weight: bold;
  color: #667eea;
  font-size: 14px;
  top: 2px;
}

/* 浅色主题 */
body.light {
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  color: #2d3748;
}

body.light .header {
  background: transparent;
}

body.light .nav {
  background: #ffffff;
}

body.light .nav-item {
  background: #ffffff;
  color: #2d3748;
}

body.light .nav-item.active {
  color: #667eea;
}

body.light .section {
  background: #ffffff;
  border: 1px solid #e2e8f0;
}

body.light .card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
}

body.light .card h3 {
  color: #1a202c;
}

body.light .theme-toggle {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: #ffffff;
}

/* 深色主题 */
body.dark {
  background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
  color: #e2e8f0;
}

body.dark .header {
  background: transparent;
}

body.dark .nav {
  background: #1e293b;
}

body.dark .nav-item {
  background: #1e293b;
  color: #e2e8f0;
}

body.dark .nav-item.active {
  color: #667eea;
}

body.dark .section {
  background: #1e293b;
  border: 1px solid #334155;
}

body.dark .card {
  background: #1e293b;
  border: 1px solid #334155;
}

body.dark .card h3 {
  color: #f1f5f9;
}

body.dark .theme-toggle {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: #ffffff;
}

/* 响应式设计 */
@media (max-width: 1024px) {
  .container {
    padding: 0 20px;
  }
  
  .section-content {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
  }
}

@media (max-width: 768px) {
  .header {
    flex-direction: column;
    gap: 15px;
    text-align: center;
    padding: 20px 0;
  }
  
  .title {
    font-size: 24px;
  }
  
  .nav {
    margin: 20px 0;
  }
  
  .nav-item {
    padding: 15px;
    font-size: 14px;
  }
  
  .section {
    padding: 25px;
  }
  
  .section-content {
    grid-template-columns: 1fr;
    gap: 15px;
  }
  
  .card {
    padding: 20px;
  }
  
  .card h3 {
    font-size: 18px;
  }
  
  .card li {
    font-size: 14px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 15px;
  }
  
  .title {
    font-size: 20px;
  }
  
  .theme-toggle {
    padding: 10px 20px;
    font-size: 13px;
  }
  
  .section {
    padding: 20px;
  }
  
  .card {
    padding: 15px;
  }
}