This has come up quite often on the WordPress.org Support forums lately and instead of searching through old posts there I am writing this post to make it a bit easier to find here.

For the WordPress Atahualpa theme (version 3.4.4 as of this writing), follow these steps to add your custom CSS if there is no option to use in its place.

  1. Go to the theme options page
  2. Near the bottom click on “Add HTML/CSS inserts”
  3. Go to the bottom of that option page for “CSS Inserts”
  4. Add: css-element { property: value; }
  5. Click on the HUGE Save Changes button

Just replace css-element { property: value; } with the styling you want to add.