Improve syntax highlighting

I've added improved support for syntax highlighting. It's definitely
still more minimal than something like Solarized, but I feel it is
a better fit for the Pixyll aesthetic.

Closes johno#195

_posts/2014-06-10-see-pixyll-in-action.md

@@ -48,6 +48,26 @@ Here's some CSS:
 }
 {% endhighlight %}
 
+Here's some JavaScript:
+
+{% highlight js %}
+var isPresent = require('is-present')
+
+module.exports = function doStuff(things) {
+  if (isPresent(things)) {
+    doOtherStuff(things)
+  }
+}
+{% endhighlight %}
+
+Here's some HTML:
+
+{% highlight html %}
+<div class="m0 p0 bg-blue white">
+  <h3 class="h1">Hello, world!</h3>
+</div>
+{% endhighlight %}
+
 # Headings!
 
 They're responsive, and well-proportioned (in `padding`, `line-height`, `margin`, and `font-size`).

_sass/_variables.scss

@@ -95,7 +95,8 @@ $form-field-padding-x: .5rem;
 $pre-border-radius: 0;
 $pre-background-color: #fafafa;
 $hljs-comment: $mid-gray;
-$hljs-keyword: $dark-gray;
+$hljs-keyword: $dark-blue;
+$hljs-name: $dark-gray;
 $hljs-number: $dark-green;
 $hljs-string: $red;
 $hljs-title: $red;

_sass/basscss/_syntax-highlighting.scss

@@ -2,20 +2,55 @@
   -webkit-text-size-adjust: none;
 }
 
+.highlight .c,
+.highlight .cs,
+.highlight .cm,
+.highlight .cp,
 .highlight .c1 {
   color: $hljs-comment;
   font-style: italic;
 }
 
 .highlight .k,
+.highlight .kc,
+.highlight .kd,
+.highlight .kn,
+.highlight .kr,
+.highlight .kt,
 .highlight .kp {
   color: $hljs-keyword;
 }
 
-.highlight .mi {
+.highlight .na,
+.highlight .nb,
+.highlight .nc,
+.highlight .no,
+.highlight .nd,
+.highlight .ni,
+.highlight .ne,
+.highlight .nf,
+.highlight .nl,
+.highlight .nn,
+.highlight .nx {
+  color: $hljs-name;
+}
+
+.highlight .mi,
+.highlight .il {
   color: $hljs-number;
 }
 
+.highlight .s,
+.highlight .sb,
+.highlight .sc,
+.highlight .sd,
+.highlight .s2,
+.highlight .s3,
+.highlight .sh,
+.highlight .si,
+.highlight .sx,
+.highlight .sr,
+.highlight .ss,
 .highlight .s1 {
   color: $hljs-string;
 }