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法学使用 CSS 中的 z-index 属性在图层中堆叠元素
使用 CSS Z-Index 属性，开发人员可将元素堆叠在彼此之上。Z-Index 可以具有正值或负值。
注意 − 如果重叠的元素未指定 z-index，则该元素将显示在文档中最后提到的元素上。
以下是实现 z-index 属性的一些示例。
z-index
在此示例中，我们设置了正 z-index 值来堆叠 −
示例
<!DOCTYPE html>
<html>
<head>
<style>
.dropbtn {
background-color: rgb(76, 78, 175);
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}
.dropbtn:hover, .dropbtn:focus {
background-color: #4f3e8e;
}
.searchField {
box-sizing: border-box;
font-size: 16px;
padding: 14px 20px 12px 45px;
border: none;
border-bottom: 1px solid #ddd;
}
.searchField:focus {outline: 3px solid #ddd;}
.dropdown {
position: relative;
display: inline-block;
}
.dropdownList {
display: none;
position: absolute;
background-color: #f6f6f6;
min-width: 230px;
overflow: auto;
border: 1px solid #ddd;
z-index: 1;
}
.dropdownList a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
}
.dropdown a:hover {background-color: #ddd;}
.show {display: block;}
</style>
</head>
<body>
<h1>Search/filterText Dropdown Example</h1>
<div class="dropdown">
<button class="dropbtn" onclick="showDropList()">Dropdown</button>
<div id="myDropdown" class="dropdownList">
<input type="text" placeholder="Search.." class="searchField">
<a href="#">Cow</a>
<a href="#">Cat</a>
<a href="#">Dog</a>
<a href="#">Giraffe</a>
<a href="#">Lion</a>
<a href="#">Leopard</a>
<a href="#">Cheetah</a>
</div>
</div>
<script>
function showDropList(){
let dropDiv = document.querySelector('.dropdownList');
if(dropDiv.style.display==="block"){
dropDiv.style.display = "";
} else {
dropDiv.style.display = "block";
}
}
document.querySelector('.searchField').addEventListener('keyup',filterDropdown);
function filterDropdown() {
var inputSearch, filterText, ul, li, links, i,div;
inputSearch = document.querySelector(".searchField");
filterText = inputSearch.value.toUpperCase();
div = document.getElementById("myDropdown");
links = div.getElementsByTagName("a");
for (i = 0; i < links.length; i++) {
txtValue = links[i].textContent || links[i].innerText;
if (txtValue.toUpperCase().indexOf(filterText) > -1) {
links[i].style.display = "";
} else {
links[i].style.display = "none";
}
}
}
</script>
</body>
</html>
负 z-index
我们来看另一个带有负值的 z-index 属性示例 −
示例
<!DOCTYPE html>
<html>
<head>
<style>
p {
margin: 0;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
div{
margin: auto;
position: absolute;
top:0;
left: 0;
right: 0;
bottom: 0;
}
div:first-child {
background-color: orange;
width: 270px;
height: 120px;
z-index: -2;
}
div:last-child {
width: 250px;
height: 100px;
z-index: -1;
background-color: turquoise;
}
</style>
</head>
<body>
<div></div>
<p>Variables are the reserved memory locations to store values. This means that when you create a variable you reserve some space in memory.............</p>
<div></div>
</body>
</html>
叠加层的 Z-index
要对图像创建叠加效果，我们使用了 z-index 属性 −
示例
<!DOCTYPE html>
<html>
<head>
<style>
body {
font-family: Arial;
}
* {
box-sizing: border-box;
}
.showBtn {
background: #008b0c;
border: none;
color:white;
padding: 10px 15px;
font-size: 20px;
cursor: pointer;
opacity: 0.8;
}
.showBtn:hover {
opacity: 1;
}
.overlay {
height: 100%;
width: 100%;
display: none;
position: fixed;
z-index: 1;
top: 0;
left: 0;
background-color: rgba(0, 0, 0, 0.747);
}
.overlay .hideBtn {
position: absolute;
top: 20px;
right: 45px;
font-size: 60px;
cursor: pointer;
color: rgb(255, 0, 0);
opacity: 0.8;
}
.overlay .hideBtn:hover {
opacity: 1;
}
.overlay input[type=text] {
padding: 15px;
font-size: 17px;
border: none;
float: left;
width: 80%;
background: white;
}
.overlay input[type=text]:hover {
background: #f1f1f1;
}
.overlay button {
float: left;
width: 20%;
padding: 15px;
background: rgb(54, 21, 241);
font-size: 17px;
border: none;
color:white;
cursor: pointer;
opacity: 0.8;
}
.overlay button:hover {
opacity: 1;
}
</style>
</head>
<body>
<div class="overlay" >
<span class="hideBtn">×</span>
<div class="searchBar">
<form >
<button type="submit">Close Overlay</button>
</form>
</div>
</div>
<h1>Overlay Effect Example</h1>
<button class="showBtn">Turn Overlay On</button>
<h2>Click on the above button to try overlay effect</h2>
<script>
document.querySelector('.hideBtn').addEventListener('click',hideSearch);
document.querySelector('.showBtn').addEventListener('click',showSearch);
function showSearch() {
document.querySelector('.overlay').style.display = "block";
}
function hideSearch() {
document.querySelector('.overlay').style.display = "none";
}
</script>
</body>
</html>
更新于： 27-Dec-2023
234 次浏览
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