Hi there!

Thanks for your query.

You can set a different logo image for your mobile devices within the basic tab of your Template Options.

However, if you want you can use the following custom code either:

@media (max-width: 991px){
#sp-header .logo-image, #sp-header.header-sticky .logo-image {
    height: 50px !important;
}
}

Note: Path towards custom CSS: Extensions>Templates>Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.

Best Regards