Added a little color and changed the font

No major changes, although I really wanted to create my own sprites to replace the default checkboxes. I just wanted to practice cloning, editing, and submitting a PR with git.
One alternative way to DRY some of this up could be something like this:

```css
.some-class {
    border: 1px solid #AAA;
    /* Since you really only want to override the color of one side */
    border-top-color: #23779C;
}
```

Not that we need to change it now. Just a little shorthand that reduces some repetition and conveys the intent a little more clearly.