Having issues with heights and backgrounds in box model

Having issues with heights and backgrounds in box modelMy site https://www.bebraveinfertilityjourney.com is behaving oddly.

I originally tried to get my sidebar to extend all the way down to the bottom of the page, which i why I started setting all my divs to “height= 100%”. It didn’t work, so I fixed it instead, which freezes the sidebar so it scrolls with you. I’m okay with this solution, but now there is a strange white background that only goes halfway down the page. If you can see, it stops right around the beginning of the next post.

I want the background of the article to be white, but it should only be about 10 pixels out on either side of the text itself. The top portion is much wider. Any ideas on what is causing this?

For your information, I am using a child theme to edit the twenty fourteen theme in wordpress. Thanks for your help!