Html – stop 100% Width Text Boxes from extending beyond their containers

csshtml

Lets say I have a text box that I want to fill a whole line. I would give it a style like this:

input.wide {display:block; width: 100%}

This causes problems because the width is based on the content of the text box. Text boxes have margin, borders, & padding by default, which makes a 100% width text box larger than its container.

For example, here on the right:

enter image description here

Is there any way to make a text box fill the width of its container without expanding beyond it?

Here is some example HTML to show what I mean:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Untitled Page</title>
    <style type="text/css">
        #outer{border: 1px solid #000; width: 320px; margin: 0px;padding:0px}
        #inner{margin: 20px; padding: 20px; background: #999;border: 1px solid #000;}
        input.wide {display:block; margin: 0px}
        input.normal {display:block; float: right}
    </style>
</head>
<body>
    <div id="outer">
        <div id="inner">
            <input type="text" class="wide" />
            <input type="text" class="normal" />
            <div style="clear:both;"></div>
        </div>
    </div>
</body>
</html>

If this is run, you can see by looking at the "normal" text box that the "wide" text box is sticking out beyond the container. The "normal" text box floats to the actual edge of the container. I'm trying to make the "wide" text box fill its container, without expanding beyond edge like the "normal" text box is.

Best Answer

Is there any way to make a text box fill the width of its container without expanding beyond it?

Yes: by using the CSS3 property ‘box-sizing: border-box’, you can redefine what ‘width’ means to include the external padding and border.

Unfortunately because it's CSS3, support isn't very mature, and as the spec process isn't finished yet, it has different temporary names in browsers in the meantime. So:

input.wide {
    width: 100%;
    box-sizing: border-box;
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
}

The old-school alternative is simply to put a quantity of ‘padding-right’ on the enclosing <div> or <td> element equal to about how much extra left-and-right padding/border in ‘px’ you think browsers will give the input. (Typically 6px for IE<8.)

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