Banner image not displayed on mobile

Site URL: https://www.kyleraineriracing.com

I am a new user of squarespace so please forgive my ignorance if this is an easy fix. After I added my logo to the header my header image is no longer visible on mobile.  Ideally I would like to have the top black header on mobile transparent to show the header picture similar to how it appears on the desktop format. Thank you for your help. 

Also, I would like to have the header logo larger but I was unable to do so independently of the navigation which messed up the padding. 

Add to Home > design > Custom CSS

/* Mobile header image */
.Mobile-bar.Mobile-bar--top {
    background: transparent;
}
@media screen and (max-width:640px) {
body.homepage {
    margin-top: 0 !important;
}
}
/* Logo size */
.Header-branding-logo {
    max-width: 350px;
}