I solved the problem just changing the CSS code:
table.bordasimples {
border-spacing: 0px;
border:1px solid #D2DDD4;
}
table.bordasimples tr td, table.bordasimples tr th
{border:1px solid #D2DDD4;}
I replaced the border-collapse for border-spacing and changed the color of borders, now my table is the way I wanted, and with a better layout.
Thanks everyone!