Changing size of sidebar

I am using Mimbo Pro and I have been trying to change the size of the sidebar. I succeed with one of them, but I cannot reduce the size of the right sidebar (widget).

File: style.css
I succeed changing the pixels of the sidebar on left, but I do not manage to change the one on the right side.

I simply changed this code to change the width of the sidebar on left:
#sidebar {
width: 270px;
float:left;
margin-right:16px;
padding:0 8px 25px 8px;
background:#FFF;
}

And also, why do all my tables get grey coloured when I have not chosen the colour? I am trying to find where I can edit it but haven’t succeeded. Example: Choose in the website below “INNHOLD” and then “TERMINLISTE”

https://www.asroma.no/?theme=Red+Earth&passkey=3051714844c307795b0fae