UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. Open the demo http://codepen.io/FezVrasta/pen/pRQrWK
2. Look at the rounded borders
3. They are jagged

What is the expected behavior?
The borders shouldn't be jagged, the page should be completely black

What went wrong?
The borders are jagged, you can se some white pixels around the shape even if the inner shape has the same size of the outer shape with the same border radius.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 56.0.2924.87  Channel: stable
OS Version: OS X 10.12.3
Flash Version: Shockwave Flash 24.0 r0

This bug has been around for more almost 10 years, still unsolved:
https://bugs.chromium.org/p/chromium/issues/detail?id=5927