I have a Categories widget, and removed the bullets.
Now I want to specify a diferent font size for each level of the Categories hierarchy...

How can I do that?

Thanks!
Alessandro

If you want each line to be different, no you can't do that without changing the code.
if you want to change the subcategories you can do that with CSS

div.widget_categories ul li a {color: red !important;}
.widget_categories ul.children li a {color: green !important;}

this will work, but you really should add teh pseudo code also