Header Opacity on homepage only

Hi - we are hoping to have our homepage only have a white background with opacity so images can be shown through in the header. Does anyone know of any code for this. Following is the domain and password:

https://mclef2023.squarespace.com/

PASSWORD: password

Thanks in advance.

Add to Design > Custom CSS

body.homepage .header-background-solid {
    opacity: 1 !important;
    background-color: rgba(255,255,255,0.3) !important;
}

Thank you so much - even better!