If you're comfortable with CSS, Sass, or are otherwise comfortable diving into some code, there are three Theme → Files you should be aware of:
- _nm-variables.scss: This file is the easiest way to change the look of your site and doesn't really require much existing knowledge of CSS/Sass. At the bottom of the file, there is a section titled Additional - Nation Media. These variables will give you a lot of control over the look and feel of your site. Just follow the existing format the variables are in while changing the values. For example, 4px might become 8px, .4 might become .2, and 15% might become 25%. You can also change all the variables in this file above the Additional - Nation Media section, though a lot of them don't need to be touched/won't have much (if any) effect on your site.
- _nm-base.scss: This is where most of the core styling lives. If you want to change some core styling, it's probably best not to do it in this file. Instead, overwrite the styling here in _nm-theme.scss (described below).
- _nm-theme.scss: Where the theme-specific styling for your theme lives. Best to include your custom styling at the bottom underneath the section titled Custom Styling. You should know CSS/Sass pretty well before modifying or adding anything to this file.