dorimuranyi

Site URL: https://dorimuranyi.squarespace.com/
Hello All, 
I have been trying to add background images to my site, but I have an issue for which I cannot seem to find the reason.
I would like the image to either be adjusted to the screen size, or display in its original size (which I would adjust to be somewhat wider than the screen).
The problem is, whatever image I set as a background, it stretches way over the size (width) of the screen - both on PC and mobile.
To give a more exact explanation, the screen resolution on my PC is set to 1366 x 768 px. Regardless if I use a 2000 x 2000 px image or a 600 x 600 image as background, it will stretch to huge dimensions for some reason, that are much bigger than the original image (I mean several times the size) and the screen too.
According to this Squarespace support article, '(...) images added through Site Styles (background images and site-wide banner images) load at their original dimensions. ' I would be fine with that, but it does not seem to be the case, or I am misunderstanding something...
https://support.squarespace.com/hc/en-us/articles/206542517-Formatting-your-images-for-display-on-the-web 
Can anyone suggest how I could get a bckground image to display either in its original size or adjusted to screen width? 
Thanks for reading!