Actively style keyboard focus, do not rely on browser defaults for keyboard focus styling.
Change background color for both mouse hover and keyboard focus styling for links and form controls.
Use border styling for keyboard focus:
Define a transparent CSS border and then give it a color when a link or form control receives focus.
Use CSS outline with an outline color and solid outline when a link or form control receives focus.
For links in the main content and complementary areas of a web page make sure they are underline for both focus and hover, but recommend they allways have underline.
Make sure all styling options meet WCAG 2.0 Level AA color contrast requirements.