Juggledad, I am using Firefox, Wordpress 3.01, and Atahualpa 3.5.3, pretty much all new versions for each. I found the codes from previous older posts on rounding. I am not sure about the spacing between the menu tabs, to make them look like folder tabs, yet. It doesnt do it, compared to the website example from the original poster. When, I copy the code that you posted, the menu tabs are spaced apart, but they are also rounded on both the top and bottom.
This makes the menus rounded for both the top and the bottom:
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div#menu1 ul.rMenu li, div#menu1 ul.rMenu li a,
div#menu2 ul.rMenu li, div#menu2 ul.rMenu li a {
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;
}
/* reset 2nd+ level */
/*
div#menu1 ul.rMenu li li, div#menu1 ul.rMenu li li a,
div#menu2 ul.rMenu li li, div#menu2 ul.rMenu li li a {
-webkit-border-radius: 0;
-moz-border-radius: 0;
border-radius: 0;
}
*/
This makes the menu buttons rounded on the bottom only:
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div#menu1,
div#menu1 ul.rMenu,
div#menu1 ul.rMenu li,
div#menu1 ul.rMenu li a:link,
div#menu1 ul.rMenu li a:hover,
div#menu1 ul.rMenu li a:visited,
div#menu1 ul.rMenu li a:active {
-moz-border-radius-bottomleft:10px;
-khtml-border-bottom-left-radius:10px;
-webkit-border-bottom-left-radius:10px;
border-bottom-left-radius:10px;
-moz-border-radius-bottomright:10px;
-khtml-border-bottom-right-radius:10px;
-webkit-border-bottom-right-radius:10px;
border-bottom-right-radius:10px;
}