Add responsiveness

Example here, thanks to @andrie

```

​
#forkongithub a{background:#FCECCC;color:#000;text-decoration:none;font-family:arial,sans-serif;text-align:center;font-weight:bold;padding:5px 40px;font-size:1rem;line-height:2rem;position:relative;transition:0.5s;}#forkongithub a:hover{background:#DFECF7;color:#000;}#forkongithub a::before,#forkongithub a::after{content:"";width:100%;display:block;position:absolute;top:1px;left:0;height:1px;background:#fff;}#forkongithub a::after{bottom:1px;top:auto;}@media screen and (min-width:1000px){#forkongithub{position:absolute;display:block;top:0;right:0;width:200px;overflow:hidden;height:200px;z-index:9999;}#forkongithub a{width:200px;position:absolute;top:45px;right:-45px;transform:rotate(45deg);-webkit-transform:rotate(45deg);-ms-transform:rotate(45deg);-moz-transform:rotate(45deg);-o-transform:rotate(45deg);box-shadow:4px 4px 10px rgba(0,0,0,0.8);}}Fork me on GitHub
```