Update color theme to white and blue

- Border accent shadow effect that makes assets float of page
- Apply border accent to image captions

_includes/image.html

@@ -1,8 +1,8 @@
 <!-- _includes/image.html -->
 {% if include.fullwidth %}
-<figure class="fullwidth">
+<figure class="border-accent fullwidth">
 {% else %}
-<figure>
+<figure class="border-accent">
 {% endif %}
     {% if include.url %}
     <a href="{{ include.url }}">