Chapter 5 - Rounded Corners - 5.3 Corner Clipping
Go to the relevant page of the specification.
- border-radius-clipping
-
Border radius clipping
When set with 'overflow: hidden', outer container should clip background of an element insides at the corners. - border-radius-overflow-hidden
-
Clipping to the border-radius curve
Effects that clip to the border or padding edge (such as 'overflow' other than 'visible') must clip to the curve