Edit in JSFiddle

<div class="redbox" id="redbox-02" style="-webkit-transform: translateX(100px);"></div>

body {
    background-color: rgba(0, 0, 0, 0.2);
}
.redbox {
    position: absolute;
    min-width: 50px;
    height: 50px;
    background-color: #f00;
    top: 25px;
    left: 25px;
    color: #fff;
    text-align: center;
    padding: 1.0em 0.8em 0 0.8em;
    font-family: monospace;
    font-size: 1.4em;
}
#redbox-02:before {
    position: absolute;
    content: '100px';
    display: block;
    color: black;
    width: 100px;
    height: 2px;
    background-color: black;
    margin: 0;
    line-height: 1.6;
    padding: 0;
    top: 22px;
    left: -100px;
}