/* 通用重置 & 基础样式 */

body {
  font-family: "Microsoft Yahei", sans-serif;
  line-height: 1.6;
}
.container {
  width: 90%;
  max-width: 1200px;
  margin: 0 auto;
}

/* 导航栏样式 */
.site-header {
  background-color: #fff;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 999;
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 0;
}
.logo img {
  height: 40px; /* Logo高度，按需调整 */
}
.menu-toggle {
  display: none; /* 移动端显示，PC端隐藏 */
  flex-direction: column;
  cursor: pointer;
}
.menu-toggle span {
  width: 25px;
  height: 3px;
  background-color: #333;
  margin: 2px 0;
  transition: 0.3s;
}
.main-nav ul {
  list-style: none;
  display: flex;
}
.main-nav li {
  margin-left: 20px;
}
.main-nav a {
  text-decoration: none;
  color: #333;
  padding: 5px 0;
  transition: color 0.3s;
}
.main-nav a.active,
.main-nav a:hover {
  color: #007bff;
}

/* 底部样式 */
.site-footer {
  background-color: #1e2b3a;
  color: #fff;
  padding: 40px 0 20px;
}
.footer-column {
  margin-bottom: 20px;
}
.footer-column h3 {
  font-size: 18px;
  margin-bottom: 15px;
}
.footer-column ul {
  list-style: none;
}
.footer-column li {
  margin-bottom: 8px;
}
.footer-column a {
  color: #ccc;
  text-decoration: none;
  transition: color 0.3s;
}
.footer-column a:hover {
  color: #fff;
}
.social-icons {
  display: flex;
  gap: 10px;
}
.social-icons a {
  display: inline-block;
  width: 36px;
  height: 36px;
  background-color: #333;
  border-radius: 50%;
  text-align: center;
  line-height: 36px;
  color: #fff;
  transition: background-color 0.3s;
}
.social-icons a:hover {
  background-color: #007bff;
}
.copyright {
  /*background-color: #18212d;*/
  padding: 10px 0;
  text-align: center;
  font-size: 14px;
}
.copyright a {
  color: #ccc;
  margin: 0 5px;
  text-decoration: none;
}
.copyright a:hover {
  color: #fff;
}

/* 回到顶部按钮 */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  display: none; /* 初始隐藏，滚动后显示 */
  width: 40px;
  height: 40px;
  background-color: #007bff;
  color: #fff;
  border-radius: 50%;
  text-align: center;
  line-height: 40px;
  cursor: pointer;
  transition: background-color 0.3s;
  z-index: 999;
}
.back-to-top:hover {
  background-color: #0056b3;
}

/* 响应式：移动端（≤768px） */
@media (max-width: 768px) {
  .menu-toggle {
    display: flex; /* 显示汉堡菜单 */
  }
  .main-nav {
    position: absolute;
    top: 70px; /* 导航栏高度，按需调整 */
    left: 0;
    width: 100%;
    background-color: #fff;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    display: none; /* 默认隐藏，点击后展开 */
  }
  .main-nav ul {
    flex-direction: column;
    padding: 10px 0;
  }
  .main-nav li {
    margin: 0;
    text-align: center;
  }
  .main-nav a {
    display: block;
    padding: 10px;
    border-bottom: 1px solid #eee;
  }
  .main-nav.active { /* 配合JS切换active类 */
    display: block;
  }
  .footer-column {
    width: 100%;
    margin-bottom: 30px;
  }
}