I am new to CSS and having problem in it

Question

Hi all,

I am new to CSS and having problem in it. I want to create a list in HTML, user can select only one item at a time, when any item in the list is moused over it is heighlited, when any item in the list is clicked it is shown in bold, when new item is selected the bold formating of the previous must be removed first.

I want to get these things done using CSS.

please help me with this, thanks in advance