Split css (#1959)

Divides the css into sub-files and normalizes how colors are defined.

Co-authored-by: Joachim <joachim.robert@protonmail.com>

bookwyrm/templates/snippets/status/layout.html

@@ -4,7 +4,7 @@
 
 {% block card-header %}
 <div
-    class="card-header-title has-background-white-ter is-block"
+    class="card-header-title has-background-secondary is-block"
     {% if main %}id="anchor-{{ status.id }}"{% endif %}
 >
     {% include 'snippets/status/header.html' with status=status %}

bookwyrm/templates/snippets/status/status_options.html

@@ -31,7 +31,7 @@
 {# things you can do to other people's statuses #}
 <li role="menuitem" class="dropdown-item p-0">
     <span class="control">
-        <a href="{% url 'direct-messages-user' status.user|username %}" class="button is-small is-white is-radiusless is-fullwidth">
+        <a href="{% url 'direct-messages-user' status.user|username %}" class="button is-small has-background-body is-radiusless is-fullwidth">
             {% trans "Send direct message" %}
         </a>
     </span>