* A border-radius + a border on a <img> tag
- The border-radius on the <img> should shrink to line up with
the border.
* A border-radius + a border on a div with overflow: hidden
- The clipping border-radius should shrink (same as the image).
This adds test pages for border-radius, CSS custom properties and
flexboxes to the default page in the Browser.
I used those files to develop said features and they can be of use
when debugging in the future or just to showcase those features.
