元素的層級的介紹
什么是元素的層級
當元素開啟定位后就會是元素提升一個層級,網頁是由多個層級組成的
<style>
*{
font-size: 50px;
font-weight: bold;
}
.box1{
width: 200px;
height: 200px;
background-color: #bfa;
opacity: .7;
position: absolute;
}
.box2{
width: 200px;
height: 200px;
background-color: red;
opacity: .7;
position: absolute;
left: 60px;
top: 60px;
}
.box3{
width: 200px;
height: 200px;
background-color: orange;
opacity: .7;
position: absolute;
left: 120px;
top: 120px;
}
</style>
<body>
<div class="box1">1</div>
<div class="box2">2</div>
<div class="box3">3</div>
</body>
通過z-index可以改變開啟定位元素的層級
<style>
*{
font-size: 50px;
font-weight: bold;
}
.box1{
width: 200px;
height: 200px;
background-color: #bfa;
position: absolute;
z-index: 3;
}
.box2{
width: 200px;
height: 200px;
background-color: red;
position: absolute;
left: 60px;
top: 60px;
z-index: 1;
}
.box3{
width: 200px;
height: 200px;
background-color: orange;
position: absolute;
left: 120px;
top: 120px;
z-index: 2;
}
</style>
<body>
<div class="box1">1</div>
<div class="box2">2</div>
<div class="box3">3</div>
</body>
父元素的層級再高也不會遮蓋住子元素
大家可以想一下,如果父元素都需要去蓋過子元素了,那設置這個子元素的意義是不是就不大了
<style>
*{
font-size: 50px;
font-weight: bold;
}
.box1{
width: 200px;
height: 200px;
background-color: #bfa;
position: absolute;
z-index: 3;
}
.box2{
width: 200px;
height: 200px;
background-color: red;
position: absolute;
left: 60px;
top: 60px;
z-index: 1;
}
.box3{
width: 200px;
height: 200px;
background-color: orange;
position: absolute;
left: 120px;
top: 120px;
z-index: 2; /* 父元素的層級再高也不會遮蓋住子元素 */
}
.box4{
width: 100px;
height: 100px;
background-color: tomato;
position: absolute;
left: 100px;
z-index: 1;
}
</style>
<body>
<div class="box1">1</div>
<div class="box2">2</div>
<div class="box3">
3
<div class="box4">4</div>
</div>
</body>
