When designing, one of the first things I do is to define some very common elements with general features like no margin/padding for body.
Similar with the body element I don’t like the outline that appears when clicking a button or a li element from a list.
To do this I write something like this:

*{outline:none;}

however… on firefox the outline still appers on buttons and submit buttons. To fix this just add:

input::-moz-focus-inner, button::-moz-focus-inner { border: 0; }