Getting logo to show on mobile in Mercer template

Site URL: https://sg-h2.squarespace.com/

I've tried a number of different options on here for logo display on mobile devices and none of them have worked for me. Any ideas for how to add my logo to the mobile site for Mercer template? Not picky but would like to have it on the dark blue page background. Here is the logo (white png so invisible):

Site password is: sgh2020

Add this to Home > Design > Custom CSS to change logo to black color on mobile

img.Mobile-bar-branding-logo {
    filter: invert(1);
}