Making an Index banner image smaller on mobile

Site URL: http://www.mintandpoppy.com

Hello! Our homepage Index banner image looks great on desktop, but when we view it on mobile - it doesn't size down enough so you can't quite see our faces (photos attached). We've tried a few different CSS codes but nothing seems to work. Any help is appreciated!

Site: www.mintandpoppy.com

Password: katieandmegan 

Add to Home > Design > Custom CSS

@media screen and (max-width:640px) {
.homepage .Parallax-item:first-child img {
    width: 100% !important;
    left: 0 !important;
    height: auto !important;
    top: 0 !important;
}
.homepage .Parallax-item:first-child figure {
    top: -200px !important;
}
section#welcome {
    height: 220px !Important;
}
}