Styling levels 4,5

The site I am working on has a menu with five levels.

I can work out how to style the top three levels but how do I style levels four and five differently from level three?

Do I need to add something to the CSS.php file in the themes folder?

hoping you can help.

thanks

Hi
yes you must style it yourself in CSS using li.levelX where X is the level deep
Ced

THANKS just to confirm.

I should set up styles

li.level4 and

li.level5 etc