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问题:

I'm trying to align some text of different sizes vertically, however, Firefox displays the smaller text way above the middle.

CSS:

div.categoryLinks {
    margin: 1em 16px;
    padding: 0 4px;
    border-width: 1px 0;
    border-style: solid;
    border-color: #ece754;
    background: #f7f5b7;
    color: #a49f1c;
    text-align: center;
    font-size: 1.4em;
}
div.categoryLinks em {
    font-size: 0.6em;
    font-style: normal;
    vertical-align: middle;
}

HTML:

<div class="categoryLinks">
    <em>SECTION:</em>
    Page One &#183;
    Page Two &#183;
    <a href="link">Page Three</a>
</div>

Screenshot:
_{(source: doheth.co.uk)}

UPDATE: just to be clear, I am aware more-or-less how vertical-align works, i.e. I already know the common misconceptions.

From more investigation, it seems like the simplest way to fix this issue is to wrap the larger text in a span and set vertical-align on that too. The two children of .categoryLinks then align relative to each other. Unless someone can show a better way without extra markup?

回答1:

Vertical align only works as expected on table cells or inline-block elements. If you want more information I suggest you read Understanding vertical-align, or "How (Not) To Vertically Center Content".

Edit: You've got something else going on because that works for me as is on Firefox. I even dropped the font size of SECTION: right down and it's still centered. Have you used Firebug to see what other CSS is affecting it?

This works as is:

<html>
<head>
<style type="text/css">
div.categoryLinks {
        margin: 1em 16px;
        padding: 0 4px;
        border-width: 1px 0;
        border-style: solid;
        border-color: #ece754;
        background: #f7f5b7;
        color: #a49f1c;
        text-align: center;
        font-size: 1.4em;
}
div.categoryLinks em {
        font-size: 0.4em;
        font-style: normal;
        vertical-align: middle;
}
</style>
</head>
<body>
<div class="categoryLinks">
        <em>SECTION:</em>
        Page One &#183;
        Page Two &#183;
        <a href="link">Page Three</a>
</div>
</body>

Note: section font size changed to 0.4em from original 0.6em to emphasize the point.

回答2:

Firefox is rendering correctly. The vertical-align property is inline, which means it doesn't apply to block elements like <div> (and <p>, etc). Try adding display: inline and see if that works.

回答3:

Vertical align is only supposed to apply to inline-block elements ( I think images are the only things that have this layout property by default), so to use it to position an inline element, first turn it into an inline block, then you can use margin and padding to position it similar to how you woudl a normal block element:

div.categoryLinks {
        margin: 1em 16px;
        padding: 0 4px;
        border-width: 1px 0;
        border-style: solid;
        border-color: #ece754;
        background: #f7f5b7;
        color: #a49f1c;
        text-align: center;
        font-size: 1.4em;

}
div.categoryLinks em {
            font-size: 0.6em;

           display:inline-block;
        vertical-align:top;
        font-style: normal;
        padding: 2px 0 0 0;

}

You have to tweak it a little for firefox 2 though, but this is because of a raer example of firefox not supporting web standards. On the other hand you could not bother with the tweak as few people still use ffx2, and it's only a very minor design flaw.

回答4:

I fixed this issues just removing:

 white-space: nowrap;

from parent div. I'm not sure why but with this rule added, Firefox doesn't apply the:

vertical-align: middle;

回答5:

I had the same problem. This works for me:

 <style type="text/css">
    div.parent {
         position: relative;
    }

    /*vertical middle and horizontal center align*/
    img.child {
        bottom: 0;
        left: 0;
        margin: auto;
        position: absolute;
        right: 0;
        top: 0;
    }
    </style>

    <div class="parent">
        <img class="child"> 
    </div>