Changing category and section backgrounds

[ProfC]

Hi folks,

A few users on my board have suggested that we change the "backgrounds" of certain sections/categories to make them more indicative of what their purpose is. I'm not 100% on how to achieve this.

I was thinking that it could be possible via CSS and <div> tags, but I'm not particularly experienced in that area.

Using the additional.css file, and some old knowledge, I've had a go on a category as a test but for some reason, the container isn't expanding to cover the entire area and it looks really scrunched up. (Please ignore the colour of the text)

Would it be possible for someone to tell me what I'm doing wrong?

Thank you in advance

In the forum description:

<class id="alexandria_castle";></class>

In additional.css

#alexandria_castle
{
   background-image:url("http://i.imgur.com/F52Yu1U.jpg");
   background-repeat: no-repeat;
   background-size: cover; 
   height: 250px;
   width: 400px;
   color: #FCFC38;
   border: 1px outset #CD7F32;
   padding: 1px;
   border-radius: 2px;
}