How did you make some of the boxes smaller? Like, these https://files.catbox.moe/yf7urn.jpeg
Also, how do you get a border around the banner, profile picture & the Feed / Question buttons?
As for the smaller boxers , and if I'm remembering correctly , I used the CSS padding property .
As for the borders around the banner , profile picture , and feed / question buttons , I had to improvise and use UBlock Origin just to know what class or ID they were under . I actually did this for most elements on my profile .
Here is a little code you can copy with the profile picture , banner and feed/question elements that I have in my current code .
The convertible pillmenu element should be for your feed/question buttons , profile avatar container element should be obvious ( your profile picture ) , and cover round shadow should be for your banner .
If you want an image border , then you can refer to this question here .