Are you saying it is responsive for mobile?
Yes, I’m saying that it is responsive for mobile.
The image size is 2000x1500 px and I tried 960 px, it was very blurry and useless.
Exactly, there is no perfect size for both, desktop and mobile devices. Small image that is good for mobile will look blurry on desktop. Large image will be scaled on mobile, but I think that it’s better than blurry on desktop.
Kind Regards, Roman.
Your server looks slow to me considering the following GTmetrix report (check Waterfall tab), so you might want to check that.