Thanks for the link! I see two things happening:
footer is not responsive
When I inspect the page, it turns out that is being caused by this CSS style, which is not part of P2 or Mercury, so it’s likely part of your Additional CSS in the Customizer, or added by a plugin you’ve installed:
#header, #footer, #wrapper {
width: 760px;
}
Because the width is set to 760px, it won’t be responsive on screens that are narrower than that. A max-width can fix it, if you need to keep that style in place:
#header, #footer, #wrapper {
width: 760px;
max-width: 100%;
}
The second is that the background image gets cut off on small screens – that’s actually normal ??
Background images can be set to size different ways:
https://www.w3schools.com/csSref/css3_pr_background-size.asp
This theme leaves the background size at auto, meaning it maintains it’s size and doesn’t do any scaling or cropping. This can work well for some images, but not all.
On your image, I’m guessing you’d rather it not be cropped on small screens. Let’s use a media query to change the sizing setting on smaller screens:
@media screen and ( max-width: 500px) {
body.custom-background {
background-size: contain;
}
}
Setting background-size: contain;
means the background should be as wide and tall as it can be, without running off the edge of the screen – so make it big, but make sure the entire image is visible ??