CSS for 'Frosted Glass' Header not working

Site URL: https://dodecahedron-disc-kbgt.squarespace.com

I'm trying to have the header be fixed but transparent with a blurred effect. This is the code I'm trying to insert:

.header-announcement-bar-wrapper {
background: inherit!important;
background-color: rgba(255, 255, 255, .3)!important;
backdrop-filter: blur(5px)!important;}

The code has worked in the past but is no longer working for me at all. Any ideas?

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