Different sizes showing for twenty twelve widget area

Hello,

I am trying to update the twenty-twelve theme (using the twenty-twelve child theme) and for some reason the two widget areas are showing different sizes. Both images are sized 410×250. Here is the link to the site: https://marvelousjjmacon.sherinahudson.com/

Also, I can’t seem to figure out how to remove the thin grey border showing underneath the image slider. I have tried the .site-content article {border-bottom:none;} and nothing happens.

Any help would be appreciated. Thanks!