Hi Christian,
For the question #1:
This at a glance the original problem I reported:
problem with the image display on the home page: when viewed from the tablet it appears blurry and grainy.
This is your answer:
Your background image is just 936 by 450 pixels. It is blurry because when using a background image in the section, the image will be stretch out to cover the whole section. I would like you to try this demo here: https://davidwalsh.name/demo/background-size.html which would explain how background image works. To resolve your issue, please upload a background image that at least 1200x800 or higher.
And this is my answer after the tests you asked for:
I had tried with bigger and smaller images but the result was always the same. Now I have set an image of 1600x914 but you can check that the tablet continues to be displayed in a blur.
I tried to find the resolution of my tablet but I can not find it. However, I imagine that you have previously done some tests considering the answers you gave me at the time: is it correct?
In any case, I try again and just found update my post.
Thank you, Alessandra.