If you want to create a table with a spreadsheet-like look, you can use the following style:

 
table, tr, td {

    border-style:solid;
    border-width:1px;
    border-color:#C6C3C6;
    border-collapse:collapse;

}

The important property here is border-collapse which makes table cells share adjacent borders. If you omit it, the default separate value will be used for this property, and the table cells will have their own borders.

Alternatively, one can use the following style with the same effect:

table {
    border-collapse: separate;
}
td {
    border: 1px solid #ccc;
}

 A very nice example on how to build a percentage bar with two images and css!

A very well organized css tutorial at CSS Basics.com.