Changing widget positions in footer of Twenty Thirteen child theme

[moderator note: corrected theme name in topic title]

Hello! Looking for some help here, extreme beginner.

In the footer of my page bachtogauss there are 2 widgets – Subscribe, and Archives. I am trying to move the Archives box over to the right, so that it’s approx 400px from left instead of current setting of 265px.

I have identified the html for the box and have tried this css:

#archives-2 {left:400px !important;
 position:  relative !important;
 }

with and without the position setting. Here’s the problem:

Originally, when the window size became smaller, Archives would jump down underneath Subscribe. When I change from 265 – 400px with above code, Archives looks great in full window size, but gets stuck out to the right and slightly under Subscribe when any smaller. It breaks the mobile look.

Looking for help on achieving:

– Archives out 400px from left in full window size
– Archives jumping directly underneath Subscribe in smaller windows, exactly as it does when the setting is 265px from left.

Sorry for wordiness – it’s hard to describe this stuff without a visual.

I have no idea how to mess with the Masonry js stuff, and am hoping for a css resolution. This is the relevant js:

element.style {
    left: 265px;
    position: absolute;
    top: 0;
}

I am working in a child theme. I also tried following these instructions for dequeueing js and whatnot, but that left me with 2 footers (the original and a broken css one), and after attempting to fix it, no footer at all.

Thanks so very much!