indeed, this code has no semantic sense at all: why would you need to put list into tag?
If you want to highlight the whole list, create id or .class with CSS properties you have now:
In CSS
#highlight{
...
}
in HTML:
...
...
As for rounded corners - if you use some example you've found elsewhere, try to recreate it on some test page where only one div with rounded corners is and after you get this code working for you, add it to your actual page.