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:
Add a CSS border when a link or form control receives focus, adjust the margin or padding width to compensate for the border with when it appears. Do not use a transparent border width, since this will not work in high contrast display modes.
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.