CSS ::before pseudo-element line-height?

Question

My paragraph has a height/line-height of 50px and text-align: center, which centers the text. But p:before is causing it to increase in height/line-height, causing the text to bump down. I want both p and p:before to be vertically centered.

http://jsfiddle.net/MMAUy/

<p>Hover This</p>

p {
    background: red;
    text-align: center;
    height: 50px;
    line-height: 50px;
    font-size: 14px;
}

p:hover:before {
    content: "icon";
    display: inline-block;
    margin-right: 10px;
    font-size: 3em;
}

The text length varies so I don't think i can just use position: absolute for the icon...

Answer 1

The reason this occurs, is because line-height is being inherited by the :before elements, which is also an inline-block element.

You could solve this by floating the :before content, thus removing it from the flow, rendering it unaffected by the line-height.

jsFiddle here

HTML

<div>
  <p>Hover This</p>
</div>

CSS

div {
    background: red;
    height: 50px;
    line-height: 50px;
    font-size: 14px;
    text-align:center;
}

div:hover p:before {
    content: "icon icon icon icon";
    margin-right: 10px;
    font-size: 42px;
    float:left;
}
p {
    display:inline-block;
    margin:0px;
}