Round corners content problem

Hey there

A while back I downloaded some code to get some round corners to work in my blog.

https://www.choicebananas.co.nz/wordpress/

I have a couple of issues though trying to get it to look how I wan’t. My html and css is pretty shocking so thanks for your guidance.

1) I would like the posts to all sit within one white box with round corners instead of having a seperate white box for each post.

2) I also want to be able to set a minimum height for this panel and the background pattern.

3) Thirdly I’d like the right hand side bar to have the same height all the time as the main content rounded corner panel.

If anyone out there can help that would be awesome

: )