I have gif as my homepage banner. It looks like it resizes correctly on my desktop but when I look at in on my phone it's getting cropped off.

Site URL: https://www.bettertogether-nn.com/

I've tried this code. It looks good on my desktop mobile view but on my actual phone it is cropped off. 

@media screen and (max-width:640px) {
.homepage .section-background img {
    width: 100% !important;
    height: auto !important;
}
}

Add this to Design > Custom CSS

/* resize banner mobile */
@media screen and (max-width:767px) {
body.homepage #page section:first-child {
    min-height: 20vh !important;
}
}