I\'m working on a project for a client built on Twitter Bootstrap. He wants to have different colour schemes that the user can select from. For example have a Red Colour Scheme
Changing the href of your style will, by itself, do nothing. The browser has already loaded your CSS and changing the HREF will not cause him to read the new file again.
Read the answer to this question, it might help you.
If a reload of the page is okay, you should probably do it on the server rather than through javascript by using some session value that defines what color scheme to use.