Edit in JSFiddle

div {
    background: #000;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 12px;
    padding: 10px;
}

a {
    background: #950006;
    background: -moz-linear-gradient(top, #de0009 0%, #950006 100%);
    background: -o-linear-gradient(top, #de0009 0%, #950006 100%);
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #de0009), color-stop(100%, #950006));
    background: -webkit-linear-gradient(top, #de0009 0%, #950006 100%);
    background: linear-gradient(top, #de0009 0%, #950006 100%);
    border: solid #dd0009;
    border-width: 1px 1px 1px 0;
    -moz-border-radius: 0 5px 5px 0;
    -webkit-border-radius: 0 5px 5px 0;
    border-radius: 0 5px 5px 0;
    display: inline-block;
    height: 28px;
    line-height: 28px;
    margin-left: 20px;
    margin-right: 2px;
    padding: 0 7px 0 3px;
    position: relative;
    text-decoration: none;
}

a:before {
    background: #950006;
    background: -moz-linear-gradient(-45deg, #de0009 0%, #950006 100%);
    background: -o-linear-gradient(-45deg, #de0009 0%, #950006 100%);
    background: -webkit-gradient(linear, left top, right bottom, color-stop(0%, #de0009), color-stop(100%, #950006));
    background: -webkit-linear-gradient(-45deg, #de0009 0%, #950006 100%);
    background: linear-gradient(-45deg, #de0009 0%, #950006 100%);
    border: solid #dd0009;
    border-width: 0 0 1px 1px;
    border-radius: 2px 0 2px 2px;
    content: '';
    display: block;
    height: 21px;
    left: -11px;
    position: absolute;
    top: 3px;
    -moz-transform: rotate(45deg);
    -webkit-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    transform: rotate(45deg);
    width: 21px;
}

a:hover, a:focus {
    border-color: #b50007;
    background: #7e0004;
    background: -moz-linear-gradient(top, #b50007 0%, #7e0004 100%);
    background: -o-linear-gradient(top, #b50007 0%, #7e0004 100%);
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #b50007), color-stop(100%, #7e0004));
    background: -webkit-linear-gradient(top, #b50007 0%, #7e0004 100%);
    background: linear-gradient(top, #b50007 0%, #7e0004 100%);
}

a:hover:before, a:focus:before {
    border-color: #b50007;
    background: #7e0004;
    background: -moz-linear-gradient(-45deg, #b50007 0%, #7e0004 100%);
    background: -o-linear-gradient(-45deg, #b50007 0%, #7e0004 100%);
    background: -webkit-gradient(linear, left top, right bottom, color-stop(0%, #b50007), color-stop(100%, #7e0004));
    background: -webkit-linear-gradient(-45deg, #b50007 0%, #7e0004 100%);
    background: linear-gradient(-45deg, #b50007 0%, #7e0004 100%);
}

a span {
    color: #fff;
    font-weight: bold;
    position: relative;
}

<h2>iOS style back buttons with CSS3</h2>
<div>
    <a href="#"><span>Back</span></a>
</div>