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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f4f7fc;
  color: #333;
  line-height: 1.6;
}

a {
  text-decoration: none;
  color: inherit;
}

/* 导航栏 */
.navbar {
  background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
  padding: 15px 30px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.navbar .logo {
  font-size: 24px;
  font-weight: 700;
  color: #fff;
  letter-spacing: 2px;
}

.navbar .logo span {
  color: #ffd700;
}

.navbar .nav-links {
  list-style: none;
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

.navbar .nav-links li a {
  color: #e0e7ff;
  font-size: 16px;
  padding: 8px 14px;
  border-radius: 25px;
  transition: all 0.3s ease;
}

.navbar .nav-links li a:hover {
  background: rgba(255,255,255,0.2);
  color: #fff;
  transform: translateY(-2px);
}

/* 主容器 */
.container {
  max-width: 1200px;
  margin: 40px auto;
  padding: 0 20px;
}

/* 卡片样式 */
.card {
  background: #fff;
  border-radius: 20px;
  padding: 25px;
  margin-bottom: 30px;
  box-shadow: 0 8px 20px rgba(0,0,0,0.06);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 30px rgba(0,0,0,0.1);
}

.card h2 {
  font-size: 22px;
  margin-bottom: 15px;
  color: #1e3c72;
  border-left: 5px solid #ffd700;
  padding-left: 12px;
}

/* 课程网格 */
.course-grid, .teacher-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.course-item, .teacher-item {
  background: #f9faff;
  border-radius: 16px;
  padding: 20px;
  border: 1px solid #e6edf5;
  transition: all 0.3s ease;
}

.course-item:hover, .teacher-item:hover {
  border-color: #2a5298;
  background: #fff;
}

.course-item h3 {
  color: #2a5298;
  margin-bottom: 8px;
}

.course-item .meta {
  color: #666;
  font-size: 14px;
  margin-bottom: 10px;
}

.course-item .price {
  font-weight: bold;
  color: #e67e22;
  font-size: 18px;
}

.teacher-item .avatar {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background: #2a5298;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  margin-bottom: 10px;
}

/* 表单 */
.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
  color: #1e3c72;
}

.form-group input, .form-group select, .form-group textarea {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid #dce3ed;
  border-radius: 12px;
  font-size: 16px;
  transition: border 0.3s ease;
}

.form-group input:focus, .form-group select:focus, .form-group textarea:focus {
  border-color: #2a5298;
  outline: none;
}

.btn {
  background: linear-gradient(135deg, #1e3c72, #2a5298);
  color: #fff;
  border: none;
  padding: 12px 30px;
  font-size: 16px;
  border-radius: 30px;
  cursor: pointer;
  transition: all 0.3s ease;
  display: inline-block;
}

.btn:hover {
  transform: scale(1.03);
  box-shadow: 0 6px 15px rgba(42,82,152,0.4);
}

.btn-gold {
  background: linear-gradient(135deg, #f7971e, #ffd200);
  color: #1e3c72;
}

/* 进度条 */
.progress-bar {
  background: #e6edf5;
  border-radius: 20px;
  height: 12px;
  overflow: hidden;
  margin: 10px 0;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #2a5298, #ffd700);
  border-radius: 20px;
  width: 0%;
  transition: width 0.5s ease;
}

/* 词汇卡片 */
.vocab-card {
  background: #fff;
  border: 2px solid #e6edf5;
  border-radius: 16px;
  padding: 20px;
  margin: 15px 0;
  cursor: pointer;
  transition: all 0.3s ease;
}

.vocab-card:hover {
  border-color: #ffd700;
  box-shadow: 0 4px 12px rgba(255,215,0,0.2);
}

.vocab-card .word {
  font-size: 24px;
  font-weight: 700;
  color: #1e3c72;
}

.vocab-card .meaning {
  color: #666;
  margin-top: 5px;
}

/* 评价 */
.review-item {
  border-bottom: 1px solid #e6edf5;
  padding: 15px 0;
}

.review-item:last-child {
  border-bottom: none;
}

.stars {
  color: #ffd700;
}

/* 页脚 */
.footer {
  background: #1e3c72;
  color: #b0c4de;
  text-align: center;
  padding: 25px 20px;
  margin-top: 40px;
}

/* 响应式 */
@media (max-width: 768px) {
  .navbar {
    flex-direction: column;
    gap: 10px;
  }
  .navbar .nav-links {
    justify-content: center;
  }
}