Can I do something like this?

table.top { background: black; color: white; width: 150px }
table.leftside { background: green; color: blue; width: 300px }

and then call:

<table class = "top"><tr><td>asdf</td></tr></table>
and
<table class = "leftside"><tr><td>asdf</td></tr></table>
and have them with their attributes?

Oh and another thing. I keep trying to change border thickness and color but it doesn't seem to want to work. I go like this:
table { border: 2px; border-color: white }
But nothing happeneds. Thanks in advance.
-andy