Excluding GB button links from styling

Hi, just need some help targeting the GB button block.

I have styled all links (excluding buttons) with:

.entry-content a:not(.button) {
	font-weight: 500;
	font-style: italic;
	border-bottom: 1px solid #444444;
}

This works fine for excluding the standard GP buttons, but I can't seem to find the selector for GB buttons.

Thanks