将两个css选项卡下的线条动画化

<div class="tab">
  <button class="tab-button active">选项卡1</button>
  <button class="tab-button">选项卡2</button>
  <div class="tab-content">
    <div class="content active">
      <h2>选项卡1的内容</h2>
      <p>这是选项卡1的内容。</p>
    </div>
    <div class="content">
      <h2>选项卡2的内容</h2>
      <p>这是选项卡2的内容。</p>
    </div>
  </div>
</div>

.tab {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.tab-button {
  background-color: #f1f1f1;
  border: none;
  padding: 10px 20px;
  cursor: pointer;
}

.tab-button.active {
  background-color: #ccc;
}

.tab-content {
  width: 100%;
  border-top: 2px solid #ccc;
  transition: border-top-color 0.5s;
}

.content {
  display: none;
  padding: 20px;
}

.content.active {
  display: block;
}

/* 添加动画效果 */
.tab-content {
  position: relative;
}

.tab-content::before {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 50%;
  height: 2px;
  background-color: #ccc;
  transition: width 0.5s;
}

.tab-button:nth-child(1):hover ~ .tab-content::before,
.tab-button:nth-child(1).active ~ .tab-content::before {
  width: 0%;
}

.tab-button:nth-child(2):hover ~ .tab-content::before,
.tab-button:nth-child(2).active ~ .tab-content::before {
  width: 100%;
}