Center a H1 tag inside a DIV

问题:

I have the following DIV inside a body tag:

<div id="AlertDiv"><h1>Yes</h1></div>

And these are their CSS classes:

#AlertDiv {
    position:absolute;
    height: 51px;
    left: 365px;
    top: 198px;
    width: 62px;
    background-color:black;
    color:white;
}

#AlertDiv h1{
    margin:auto;
    vertical-align:middle;
}

How can I align vertically and horizontally H1 inside DIV?

AlertDiv will be bigger than H1.

回答1:

You can add line-height:51px to #AlertDiv h1 if you know it's only ever going to be one line. Also add text-align:center to #AlertDiv.

#AlertDiv {
    top:198px;
    left:365px;
    width:62px;
    height:51px;
    color:white;
    position:absolute;
    text-align:center;
    background-color:black;
}

#AlertDiv h1 {
    margin:auto;
    line-height:51px;
    vertical-align:middle;
}

The demo below also uses negative margins to keep the #AlertDiv centered on both axis, even when the window is resized.

Demo: jsfiddle.net/KaXY5

回答2:

There is a new way using transforms. Apply this to the element to centre. It nudges down by half the container height and then 'corrects' by half the element height.

position: relative;
top: 50%;
transform: translateY(-50%);
-webkit-transform: translateY(-50%);
-ms-transform: translateY(-50%);

It works most of the time. I did have a problem where a div was in a div in a li. The list item had a height set and the outer divs made up 3 columns (Foundation). The 2nd and 3rd column divs contained images, and they centered just fine with this technique, however the heading in the first column needed a wrapping div with an explicit height set.

Now, does anyone know if the CSS people are working on a way to align stuff, like, easily? Seeing that its 2014 and even some of my friends are regularly using the internet, I wondered if anyone had considered that centering would be a useful styling feature yet. Just us then?

回答3:

On the hX tag

width: 100px;
margin-left: auto;
margin-right: auto;

回答4:

<div id="AlertDiv" style="width:600px;height:400px;border:SOLID 1px;">
    <h1 style="width:100%;height:10%;text-align:center;position:relative;top:40%;">Yes</h1>
</div>

You can try the code here:

http://htmledit.squarefree.com/

回答5:

Started a jsFiddle here.

It seems the horizontal alignment works with a text-align : center. Still trying to get the vertical align to work; might have to use absolute positioning and something like top: 50% or a pre-calculated padding from the top.

回答6:

You could add padding to the h1:

#AlertDiv h1 {
  padding:15px 18px;
}

回答7:

You can use display: table-cell in order to render the div as a table cell and then use vertical-align like you would do in a normal table cell.

#AlertDiv {
    display: table-cell;
    vertical-align: middle;
    text-align: center;
}

You can try it here: http://jsfiddle.net/KaXY5/424/