JS/CSS 侧边栏动画实例 – 页面主体内容黑色透明背景

HTML部分

<div id="mySidenav" class="sidenav">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">×</a>
  <a href="#">About</a>
  <a href="#">Services</a>
  <a href="#">Clients</a>
  <a href="#">Contact</a>
</div>

<div id="main">
  <h2>侧边栏实例 - 页面主体向右移动</h2>
  <p>点击以下菜单图标打开侧边栏，主体内容向右偏移。主体内容添加黑色透明背景</p>
  <span style="font-size:30px;cursor:pointer" onclick="openNav()">☰ open</span>
</div>

CSS部分

body {
    font-family: "Lato", sans-serif;
    transition: background-color .5s;
}

.sidenav {
    height: 100%;
    width: 0;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: #111;
    overflow-x: hidden;
    transition: 0.5s;
    padding-top: 60px;
}

.sidenav a {
    padding: 8px 8px 8px 32px;
    text-decoration: none;
    font-size: 25px;
    color: #818181;
    display: block;
    transition: 0.3s;
}

.sidenav a:hover, .offcanvas a:focus{
    color: #f1f1f1;
}

.sidenav .closebtn {
    position: absolute;
    top: 0;
    right: 25px;
    font-size: 36px;
    margin-left: 50px;
}

#main {
    transition: margin-left .5s;
    padding: 16px;
}

@media screen and (max-height: 450px) {
  .sidenav {padding-top: 15px;}
  .sidenav a {font-size: 18px;}
}

JS部分

function openNav() {
    document.getElementById("mySidenav").style.width = "250px";
    document.getElementById("main").style.marginLeft = "250px";
    document.body.style.backgroundColor = "rgba(0,0,0,0.4)";
}

function closeNav() {
    document.getElementById("mySidenav").style.width = "0";
    document.getElementById("main").style.marginLeft= "0";
    document.body.style.backgroundColor = "white";
}

实现效果

展开前

展开后