diagonal.css

<span class="ge" style="
    position: absolute;
    width: 75%;
    height: 1px;
    background: #666;
    top: 0;
    right: 0;
    -webkit-transform: translateX(-9%) translateY(0px) rotateZ(-53deg) scaleX(1);
    z-index: -1;
    -webkit-transform-origin: top right;
"></span>
 
<span class="ge" style="
    position: absolute;
    width: 60%;
    height: 1px;
    background: #999;
    top: 0;
    right: 0;
    -webkit-transform: translateX(-32%) translateY(177px) rotateZ(-53deg) scaleX(1);
    z-index: -1;
    -webkit-transform-origin: center center;
"></span>
 
<span class="ge" style="
    position: absolute;
    width: 85%;
    height: 1px;
    background: #aaa;
    bottom: 0;
    left: 0;
    -webkit-transform: translateX(6%) translateY(30px) rotateZ(-53deg) scaleX(1);
    z-index: -1;
    -webkit-transform-origin: left bottom;
"></span>