.git-link {
    z-index: 100;
    position: fixed;
    top: 0;
    left: 0;
    border: 0;
    height: 149px;
    width: 149px;
    background-image: url(//images2015.cnblogs.com/blog/459873/201603/459873-20160317090540131-1089895320.png);
}