Single instead of double quote inside liquid

Replaces the double quotes in your css link with single quotes:

```
<link rel="stylesheet" href="{{ "/css/main.css" | prepend: site.baseurl }}">
```

new:

```
<link rel="stylesheet" href="{{ '/css/main.css' | prepend: site.baseurl }}">
```

This could otherwise cause trouble with the double quotes inside the HTML tag. Also you have not set `baseurl` in your _config.yml currently. You may want to set it to `xtargets`. Further information: [Clearing Up Confusion Around Baseurl](http://blog.parkermoore.de/2014/04/27/clearing-up-confusion-around-baseurl/)