I set the width in the admin -> config -> layout settings to 0px for each column.
I recommended:
Your design shows 2 equal columns under the head and you can attain this with the cart by eliminating one of the 3 that are available throught he admin > config > layoutsettings > and either right or left global.

While there set the remaining one to a width that will be half of the available space
This should get you on the correct track
Only set one to be off globally....and scrap your tables and work/design with in the cart structure that is mostly div based