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/* Modernizr 2.6.2 (Custom Build) | MIT & BSD
 * Build: http://modernizr.com/download/#-cssclasses-addtest-teststyles
 */
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// Detects if the browser is wrongly adding padding to min-height
// by Volker Rose | @riddla
// http://volker-rose.de/blog/box-sizing-and-min-height-css-trouble-within-firefox/
// http://jsfiddle.net/riddla/4bP73/
Modernizr.testStyles('#modernizr { -webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; min-height: 100px; padding-top: 10px; position: absolute; top: -2000em; }', function(elem, rule){
    Modernizr.addTest('padding-added-to-minheight', elem.scrollHeight === 110);
});

<p id="padding-added-to-minheight">Your Browser adds padding to min-height :(</p>
<p id="no-padding-added-to-minheight">Your Browser doesn't add padding to min-height, good boy :)</p>

<div class="box"><span>This box has a height of 100px</span></div>
<div class="box" id="box"><span>This box should also have a height of 100px</span></div>
<div class="box" id="box-with-applied-fix"><span>This box has a fix applied</span></div>

* { font-family:sans-serif; }
body { text-align:center }

p {
    display:none;     
    padding:10px;
    color:#FFF;
    margin-bottom:2em;
}

#box-with-applied-fix,
.no-padding-added-to-minheight #box,
#no-padding-added-to-minheight { background:green; }

.padding-added-to-minheight #box,
#padding-added-to-minheight { background:red; }

.no-padding-added-to-minheight #no-padding-added-to-minheight,
.padding-added-to-minheight #padding-added-to-minheight { display:block; }

.box {
    box-sizing:border-box;
    margin:0;
    padding:0;
    background:#666;
    color:#FFF;
    height:100px;
    width:100px;
    display:inline-block;
    vertical-align:top;
    font-size:14px;
}

.box span { display:block; margin:10px; }

#box-with-applied-fix span,
#box span { margin-top:0; }

#box-with-applied-fix,
#box { padding:10px 0; }

.padding-added-to-minheight #box-with-applied-fix { height:80px; }