方法一:margin:auto法
定義上下左右爲0,margin:auto,實現脫離文檔流的居中
//css
.div1 {
position: relative;
width: 200px;
height: 200px;
border: 3px solid forestgreen;
margin-bottom: 20px;
}
.div2 {
position: absolute;
width: 100px;
height: 100px;
background: goldenrod;
margin: auto;
top: 0;
left: 0;
right: 0;
bottom: 0;
}
//html
<div class="div1">
<div class="div2">
margin:auto法
</div>
</div>
方法二:margin負值法
// css
.div3 {
position: absolute;
width: 100px;
height: 100px;
background: goldenrod;
top: 50%;
left: 50%;
margin-top: -50px;
margin-left: -50px;
/* 或者 */
/* transform: translateX(-50%);
transform: translateY(-50%); */
}
// html
<div class="div1">
<div class="div3">
margin負值法
</div>
</div>
方法三:利用table-cell(未脫離文檔流)
設置父元素的display:table-cell,並且vertical-align:center,這樣可以讓子元素的div實現垂直居中。
//css
.div4 {
position: relative;
width: 200px;
height: 200px;
border: 3px solid forestgreen;
margin-bottom: 20px;
display: table-cell;
vertical-align: middle;
text-align: center;
}
.div5 {
width: 100px;
height: 100px;
background: goldenrod;
}
// html
<div class="div4">
<div class="div5">
table-cell
</div>
</div>
方法四:利用flex
將父元素設置爲display: flex;,並且設置align-items: center;justify-content: center;
// css
.div6 {
position: relative;
width: 200px;
height: 200px;
border: 3px solid forestgreen;
display: -webkit-flex;
display: flex;
-webkit-align-items: center;
align-items: center;
-webkit-justify-content: center;
justify-content: center;
}
.div7 {
width: 100px;
height: 100px;
background: goldenrod;
}
// html
<div class="div6">
<div class="div7">
利用flex
</div>
</div>