更新不过来

水平居中

inlink-block text-align

<style>
.parent{
    width: 100%;
    height: 50px;
    background: red;
    text-align: center;
}
.child{
    display: inline-block;
    background: #ccc;
}
</style>
<div class="parent">
    <div class="child">我相信这么优秀的你，一定会成功的</div>
</div>

table margin

<style>
.parent{
    width: 100%;
    height: 50px;
    background: red;
}
.child{
    display: table;
    margin: 0 auto;
    background: #ccc;
}
</style>
<div class="parent">
    <div class="child">我相信这么优秀的你，一定会成功的</div>
</div>

absolute transform

<style>
.parent{
    width: 100%;
    height: 50px;
    background: red;
    position: relative;
}
.child{
    background: #ccc;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
}
</style>
<div class="parent">
    <div class="child">我相信这么优秀的你，一定会成功的</div>
</div>

flex margin

<style>
.parent{
    width: 100%;
    height: 50px;
    background: red;
    display: flex;
}
.child{
    background: #ccc;
    margin: 0 auto;
}
</style>
<div class="parent">
    <div class="child">我相信这么优秀的你，一定会成功的</div>
</div>

flex justify-content

<style>
.parent{
    width: 100%;
    height: 50px;
    background: red;
    display: flex;
    justify-content: center;
}
.child{
    background: #ccc;
}
</style>
<div class="parent">
    <div class="child">我相信这么优秀的你，一定会成功的</div>
</div>

垂直居中

table-cell vertical-align

<style>
.parent{
    width: 100px;
    height: 100px;
    background: red;
    display: table-cell;
    vertical-align: middle;
}
.child{
    background: #ccc;
}
</style>
<div class="parent">
    <div class="child">学无止境</div>
</div>

absolute transform

<style>
.parent{
    width: 100px;
    height: 100px;
    background: red;
    position: relative;
}
.child{
    background: #ccc;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
}
</style>
<div class="parent">
    <div class="child">学无止境</div>
</div>

flex align-items

<style>
.parent{
    width: 100px;
    height: 100px;
    background: red;
    display: flex;
    align-items: center;
}
.child{
    background: #ccc;
}
</style>
<div class="parent">
    <div class="child">学无止境</div>
</div>

水平垂直居中

absolute transform

<style>
.parent{
    width: 400px;
    height: 100px;
    background: red;
    position: relative;
}
.child{
    background: #ccc;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}
</style>
<div class="parent">
    <div class="child">学无止境</div>
</div>

line-block text-align table-cell vertical-align

<style>
.parent{
    width: 400px;
    height: 100px;
    background: red;
    display: table-cell;
    vertical-align: middle;
    text-align: center;
}
.child{
    background: #ccc;
    display: inline-block;
}
</style>
<div class="parent">
    <div class="child">学无止境</div>
</div>

flex justify-content align-items

<style>
.parent{
    width: 400px;
    height: 100px;
    background: red;
    display: flex;
    justify-content: center;
    align-items: center;
}
.child{
    background: #ccc;
}
</style>
<div class="parent">
    <div class="child">学无止境</div>
</div>