左上角的斜条

#sources {
    display: block;
    position: fixed;
    _position: absolute;
    top: 0;
    left: 0;
    top: -20px\9;
    left: -20px\9;
    width: 200px;
    height: 28px;
    background-color: #333;
    color: #fff;
    font: bold 14px/28px georgia,sans-serif;
    text-align: center;
    -moz-transform: translate(-40px,45px) rotate(-45deg);
    -webkit-transform: translate(-40px,45px) rotate(-45deg);
    -o-transform: translate(-40px,45px) rotate(-45deg);
    transform: translate(-40px,45px) rotate(-45deg);
    -moz-box-shadow: 0 0 5px rgba(0,0,0,.5),inset 0 0 2px #fff;
    -webkit-box-shadow: 0 0 5px rgba(0,0,0,.5),inset 0 0 2px #fff;
    box-shadow: 0 0 5px rgba(0,0,0,.5),inset 0 0 2px #fff;
    text-shadow: 1px 1px 1px rgba(0,0,0,.1);
    filter: progid:DXImageTransform.Microsoft.Matrix(sizingMethod='auto expand',M11=.7,M12=0.6,M21=-.7,M22=0.6);
}

<a href="#" id="sources">Fork Me on github</a>