Could it be that one of the rules has a syntax error?
It would be good to see the css and tables but this worked. Not sure if it what you want.
[HTML]
| cell item | cell item | cell item |
|
heres the css from the external style sheet
.t1 { border: 4px solid blue; }
.t2 { border: 2px solid red; }
.t1 td { border: 1px solid green; }
.t2 td { border: 1px dashed black; }[/HTML]