How to dynamically change a class css styling?

Question

Goal

In my program I want to do both things with jquery/javascript:

1. Change styling of css classes dynamically
2. Add/remove classes to elements

Answer 1

@synthet1c has described the problem. My solution is:

$("head").append('');
var element = $("head").children(':last');
element.html('.redclass{color: darkred;}');