* {
  margin: 0;
  padding: 0;
}

body {
  background-color: #f1f2f3;
}

.container {
  box-sizing: border-box;
  width: 100%;
  max-width: 1560px;
  min-width: 1240px;
  margin: 20px auto;
  color: #333;
  line-height: 1.5;
}

.container *{
  box-sizing: border-box;
}

header {
  width: 100%;
  text-align: center;
  margin-bottom: 25px;
}

header h1 {
  font-size: 2.2rem;
  font-weight: 600;
  margin-bottom: 5px;
}

header p {
  font-size: 1.1rem;
  opacity: 0.9;
}

/* 导航样式 */
.tabs {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 30px;
}

.tab-btn {
  background: white;
  border: none;
  border-radius: 50px;
  padding: 14px 50px;
  margin: 0 20px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.08);
  display: flex;
  align-items: center;
  min-width: 220px;
  justify-content: center;
}

.tab-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 15px rgba(0, 0, 0, 0.12);
}

.tab-btn.active {
  background: #ff6b6b;
  color: white;
  box-shadow: 0 4px 15px rgba(255, 107, 107, 0.4);
}

.tab-btn span {
  margin-right: 8px;
  font-size: 1.3rem;
}

/* 内容区域样式 */
.content-section {
  background: white;
  border-radius: 12px;
  padding: 20px;
  margin-bottom: 25px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.05);
}

.section-title {
  text-align: center;
  margin-bottom: 10px;
  color: #444;
  font-size: 1.6rem;
  position: relative;
  padding-bottom: 5px;
}

.section-title:after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 120px;
  height: 4px;
  background: linear-gradient(90deg, #4a90e2, #5e35b1);
  border-radius: 2px;
}

.section-description {
  text-align: center;
  margin-bottom: 25px;
  font-size: 1rem;
  opacity: 0.8;
}

/* 卡片网格布局 */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 20px;
}

.card {
  background: white;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.06);
  transition: all 0.3s ease;
  cursor: pointer;
  text-align: center;
  border: 1px solid #eee;
  position: relative;
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: 0 12px 25px rgba(0, 0, 0, 0.12);
  border-color: #4a90e2;
}

.card-content {
  padding: 25px 15px;
}

.card-letter {
  font-size: 3.2rem;
  font-weight: bold;
  color: #4a90e2;
  margin-bottom: 6px;
}

.card-hanzi {
  font-size: 1.2rem;
  color: #666;
}

.play-icon {
  position: absolute;
  top: 10px;
  right: 10px;
  background: #f1f2f3;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  color: #4a90e2;
  transition: all 0.2s;
}

.card:hover .play-icon {
  background: #4a90e2;
  color: white;
}

/* 子类别样式 */
.sub-category {
  margin-top: 20px;
}
.sub-category .section-description{
  text-align: left;
}

.sub-title {
  font-size: 1.3rem;
  color: #5e35b1;
  margin-bottom: 10px;
  padding-left: 10px;
  border-left: 4px solid #ff6b6b;
}

/* 页脚样式 */
footer {
  background: #333;
  color: #fff;
  padding: 30px 0 10px;
  margin-top: 25px;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}

.footer-section h3 {
  font-size: 1.4rem;
  margin-bottom: 20px;
  position: relative;
  padding-bottom: 10px;
  color: #fff;
}

.footer-section h3:after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 50px;
  height: 3px;
  background: #4a90e2;
}

.footer-section p {
  margin-bottom: 15px;
  color: #ccc;
}

.copyright {
  text-align: center;
  padding-top: 20px;
  margin-top: 20px;
  border-top: 1px solid #444;
  color: #999;
  font-size: 0.95rem;
}