Inner Border Radius

Sets the inner radius of the border, in pixels.

The inner and outer radius (border-radius) of the border have separate controls. The radius can also be controlled individually by using a set of four comma-separated values to define each corner. This makes common use cases such as only rounding the top or bottom simple to implement.

For evenly-rounded borders, we recommend setting border-radius-inner to 1/2 the value of border-radius if border has a value higher than both radius values; if not, then setting to 3/4 the value of border-radius will work better.

The border parameter must be set for this operation to be applied.