body {
  font-family: Arial, sans-serif;
  background-color: #f4f4f4;
  color: #333;
  margin: 0;
  padding: 0;
}

.container {
  display: flex;
  max-width: 1200px;
  margin: 0 auto;
}

.sidebar {
  width: 25%;
  background-color: #e3e3e3;
  padding: 20px;
  box-sizing: border-box;
}

.main-content {
  width: 75%;
  padding: 20px;
  background-color: #ffffff;
  box-sizing: border-box;
}

header {
  background-color: #f4f4f4; /* 顶部导航栏背景颜色 */
  padding: 10px 20px;
  <!--  display: flex;
  justify-content: flex-end; /* 将导航栏内容推到右边 */ -->
}

.top-nav ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  display: flex; /* 将导航链接水平排列 */
  justify-content: flex-start; /* 将导航栏内容推到左边 */
}

.top-nav ul li {
  margin-left: 20px; /* 控制链接之间的间距 */
}

.top-nav ul li a {
  text-decoration: none;
  color: #333; /* 链接颜色 */
  font-weight: bold;
  padding: 8px 16px;
  border-radius: 4px;
}

.top-nav ul li a:hover {
  background-color: #e0e0e0; /* 悬停时的背景颜色 */
}

.content {
  margin-top: 20px;
}