根据重叠的部分切换汉堡菜单背景

<div class="menu-container">
  <input type="checkbox" id="menu-toggle" />
  <label for="menu-toggle" class="menu-icon">
    <span class="line"></span>
    <span class="line"></span>
    <span class="line"></span>
  </label>
  <nav class="menu">
    <!-- 菜单项 -->
  </nav>
</div>

.menu-container {
  position: relative;
}

.menu-icon {
  position: absolute;
  top: 20px;
  left: 20px;
  z-index: 2;
  cursor: pointer;
}

.line {
  display: block;
  width: 30px;
  height: 3px;
  margin-bottom: 5px;
  background-color: #000;
  transition: transform 0.3s ease-in-out;
}

#menu-toggle:checked ~ .menu-icon .line:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

#menu-toggle:checked ~ .menu-icon .line:nth-child(2) {
  opacity: 0;
}

#menu-toggle:checked ~ .menu-icon .line:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

.menu {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: #fff;
  opacity: 0.9;
  transform: translateX(-100%);
  transition: transform 0.3s ease-in-out;
}

#menu-toggle:checked ~ .menu {
  transform: translateX(0);
}

// 点击菜单项后关闭菜单
var menuItems = document.querySelectorAll('.menu a');
for (var i = 0; i < menuItems.length; i++) {
  menuItems[i].addEventListener('click', function() {
    document.getElementById('menu-toggle').checked = false;
  });
}