How to add a filter to header images only?

@atmos For Cart page, try this code only change (body[class*="type-products"].view-item  to  #cart)

#cart header#header .sqs-announcement-bar {
    height: 49px !important;
    min-height: unset !important;
}

#cart header#header .sqs-announcement-bar-dropzone {
    min-height: unset !important;
}

#cart header#header .header-announcement-bar-wrapper {
    height: 100% !important;
}

#cart header#header:has(.sqs-announcement-bar) .header-announcement-bar-wrapper {
    height: calc(~'100% - 49px') !important;
    padding-top: 0 !important;
    padding-bottom: 0 !important;
}
#cart header#header:has(.sqs-announcement-bar.sqs-announcement-bar-hidden) .header-announcement-bar-wrapper {
    height: 100% !important;
    padding-top: 0 !important;
    padding-bottom: 0 !important;
}

#cart header#header .header-dropshadow {
    height: 100%;
    background: #000 !important;
    opacity: 0.75 !important;
}

#cart header#header .header-inner {
    align-items: flex-start !important;
    height: 100% !important;
}

/* Mobile styles */
@media screen and (max-width: 767px) {
    #cart header#header .sqs-announcement-bar {
        height: 100px !important;
    }

    #cart header#header:has(.sqs-announcement-bar) .header-announcement-bar-wrapper {
        height: calc(~'100% - 100px') !important;
        padding-top: 0 !important;
        padding-bottom: 0 !important;
    }

    #cart header#header:has(.sqs-announcement-bar.sqs-announcement-bar-hidden) .header-announcement-bar-wrapper {
       height: 100% !important;
       padding-top: 0 !important;
       padding-bottom: 0 !important;
    }
}

@Lesum it looks great on my end. Would you mind checking it on your side like you did with the product page?

@atmos Awesome! I just checked; it's working correctly. 

Just now, Lesum said:

@atmos Awesome! I just checked; it's working correctly. 

Thank you so much for your help. I never would have figured that out on my own. Really appreciate it! I noticed that you have a Buy Me A Coffee site. I’ll definitely contribute something. I may take you up on your paid Squarespace service too at some point if you can help with the optimisation side of things.