This extension allows you to easily add the effect of the thin table border, by nesting one table within the other.
It is done by nesting two tables. Just choose the width (percent or pixels) the border colour,the colour of the inner table itself and the number of columns and rows you wish within the inner table.
I have added text fields beside the colorpicker to allow a user to manually enter the colour. As well as making the borderwidth variable as well now.