只使用Bootstrap类:

Div: class="容器d-flex" div中的元素:class="m-auto"

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.5.3/css/bootstrap.min.css" crossorigin="anonymous"> < span class=" font - family:宋体" style=" font - family:宋体;background - color: # 333;" > < h2 class = " m-auto " > < a href = " https://hovermind.com/ " > H➲版本➾M⇡ND < / > < / h2 > < / div >

使用display flex，首先你需要包装你想对齐的项目的容器:

<div class="outdiv">
    <div class="indiv">
        <span>test1</span>
        <span>test2</span>
    </div>
</div>

然后在我的例子中应用下面的CSS内容来包装div或outdiv:

.outdiv {
    display: flex;
    justify-content: center;
    align-items: center;
}

在父div中创建中央子div的三种方法

绝对定位法 Flexbox方法 变换/翻译方法

Demo

/* Absolute Positioning Method */ .parent1 { background: darkcyan; width: 200px; height: 200px; position: relative; } .child1 { background: white; height: 30px; width: 30px; position: absolute; top: 50%; left: 50%; margin: -15px; } /* Flexbox Method */ .parent2 { display: flex; justify-content: center; align-items: center; background: darkcyan; height: 200px; width: 200px; } .child2 { background: white; height: 30px; width: 30px; } /* Transform/Translate Method */ .parent3 { position: relative; height: 200px; width: 200px; background: darkcyan; } .child3 { background: white; height: 30px; width: 30px; position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); } <div class="parent1"> <div class="child1"></div> </div> <hr /> <div class="parent2"> <div class="child2"></div> </div> <hr /> <div class="parent3"> <div class="child3"></div> </div>

下面是另一种(响应性的)方法:

html,
    body {
        height: 100%;
    }
    body {
        margin: 0;
    }

    .table {
        display: table;
        width:  auto;
        table-layout:auto;
        height: 100%;
    }
        .table:nth-child(even) {
            background: #a9edc3;
        }
        .table:nth-child(odd) {
            background: #eda9ce;
        }

    .tr {
        display: table-row;
    }
    .td {
        display: table-cell;
        width: 50%;
        vertical-align: middle;
    }

http://jsfiddle.net/herrfischerhamburg/JcVxz/

我一个朋友的一个技巧:

Div:前面{内容:" ";显示:inline-block;高度:100%;vertical-align:中间;} Div p{显示:inline-block;} < div风格= "高度:100 px;边界:1 px固体;" > < span style=" font - family:宋体;"</p> .我是垂直居中的 < / div >

演示。

对我来说，它是这样工作的:

<div style="width:70px; height:68px; float:right; display: table-cell; line-height: 68px">
    <a href="javascript:void(0)" style="margin-left: 4px; line-height: 2" class="btn btn-primary">Login</a>
</div>

“a”元素转换为按钮，使用Bootstrap类，它现在垂直居中在一个外部的“div”。