Making part of a div transparent

Question

I\'m trying to do something like this in HTML. It\'s a header, at the very top of the page. T

Answer 1

It may be possible with a CSS-alpha mask: https://caniuse.com/#feat=css-masks

update 1

• Create a DIV-layer ontop
• Insert a CANVAS-element. Paint the black parts black, the rest should be transparent.

update 2

I am pretty sure, that there is no way to create this layout without using PNG-images with an alpha-layer in older browser.