Image Overlay

Hi guys,

I'm working on a site (https://parkerisaacadipress.squarespace.com) built on the Stanton Template.  I'd like to remove the transparency overlay being applied to the cover page image. I've searched the forums, and found an answer to this same question for someone using the Naomi template. They ended up using custom CSS code that fixed the issue: 

.homepage .index-image-overlay {
    background: rgba(28,13,10,0);
}

However, when I tried this in my template it didn't work. I came across two issues: 1) it didn't seem to "take" - once I pasted the code there wasn't an "apply" or "save" button so nothing changed. 2) there's a "note" explaining "custom CSS does not apply to cover pages - so I imagine since this image overlay exists on the "home" page, the code won't take... 

Can anyone help to figure this out? Thank you so much in advance.

Regards, Kristy