/* 基础样式 */
body {
  margin: 0;
  font-family: sans-serif;
  background: #f7f7f7;
  color: #222;
  line-height: 1.6;
}

/* 页眉 */
header {
  background: #2c3e50;
  color: white;
  text-align: center;
  padding: 1.5rem 1rem;
}

/* 主体内容 */
main {
  max-width: 800px;
  margin: 2rem auto;
  background: white;
  padding: 2rem 1rem;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

/* 页脚 */
footer {
  text-align: center;
  padding: 1rem;
  background: #eee;
  margin-top: 3rem;
}

/* 链接样式 */
a {
  color: #2980b9;
  text-decoration: none;
  word-break: break-all;
}
a:hover {
  text-decoration: underline;
}

/* 动画淡入效果 */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: all 1s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* 小屏设备优化 */
@media screen and (max-width: 600px) {
  header h1 {
    font-size: 1.5rem;
  }

  main {
    padding: 1.5rem 1rem;
  }

  ul {
    padding-left: 1.2rem;
  }

  a {
    font-size: 1rem;
  }

  p, li {
    font-size: 1rem;
  }
}