How to grey background text of and

 elements on Tumblr

You are using <pre> tags when you should be using <code> tags

Pre retains the format

Example

Pre

modules = ['meta-gnome-core', 'meta-gnome-apps-featured']  # This is what is built by the build slaves (http:build.gnome.org/)

Code
modules = ['meta-gnome-core', 'meta-gnome-apps-featured'] # This is what is built by the build slaves (http:build.gnome.org/)

I've got another idea.

{block:Tags}<a class="tag" href="{TagURL}">{Tag}</a><span class="tagtail"></span>{/block:Tags}

This will add a span with the "tagtail" class after every tag.

Then, add this css:

span.tagtail + a.tag:before {
   content:", ";
}

This will select every tag anchor that comes after a tagtail span (so every one but the first). This way, we avoid the need to use the first-child or last-child selectors.

UPDATE:

If you want to ensure that the commas are styled apart from the anchor, I suppose you could also do:

{block:Tags}<span class="taghead">, </span><a class="tag" href="{TagURL}">{Tag}</a>{/block:Tags}

and then style it like:

span.taghead { display:none; }
a.tag + span.taghead { display:inline; }

However, this might need tweaking because browsers differ on overriding rules.