This is the glass from my site's header and nav, on its own. Slide from clear to frost and drag the pane over the colour.
At the clear end there is almost no blur, so the edge catches the light like a real pane. As it frosts, the blur and colour come up and the edge fades, because frost carries the shape instead.
It starts at the level you picked on my site, if you did. Built with CSS backdrop-filter.