Alignment Problems

I just installed a theme and made no adjustments to it other than changing the image (kept the size exactly the same though) and for some reason my sidebar is showing up as though it has been pushed to the bottom! I have tried a few other templates as well and the same thing has happened to them. What gives? Is something messed up in the CSS?

Any help would be appreciated. Here’s the blog.

https://www.austinsurfboards.com/blog