CSS for image position and size

Site URL: https://fabrizioscippa.squarespace.com/

Hello Spacers,

I'd like to have an image (my logotype) to be positioned in the upper left margin of every first/top section of my website (All pages).

The issue is that the image resizes randomly (becomes very small or too large on mobile) and shifts position. At the moment I added it only on home page and one project but I'd like it on each page on the same position. 

I'm attaching here a screen shot of the approximate size and position I'm aiming for. It can become a little smaller or larger depending on user screen size but now there is way too much resizing and shifting.

Thank you!

https://fabrizioscippa.squarespace.com/
password: fsg

You mean this image? Add it in same position on all pages?

Yes on all pages.

Similar size to all pages and do not show on mobile view.

Thanks!!