How do I stop the tabs on the 'my account' page from over running the right side doesn't matter if I use IE7 or FF 3.x

I am new to theming and styling, it has taken me long enough to learn the Drupal system and modules, though I can find my way around the files and I know some html as well as I like to think that I understand some of the CSS.

I would sure appreciate a tip! I have included a screen shot of what I am seeing on my site.
I have attached a screen shot to this request. Thanks in advance.

#1 user-tab-screenshot.png49.72 KBkomal.savla
mymiracleschool.jpg222.67 KBlazoe16


komal.savla’s picture

49.72 KB

I have tried to fix this by adding following css :

ul.primary {
  float: left;
  width: 100%;
  border: 0;

ul.primary li{
  float: left;
  margin: 1em 0 0 0;
  border-bottom:1px solid #BBBBBB;

I have attached the screenshot of how it looks after adding the above css. Hope this helps.