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 ½ the value of
border has a value higher than both radius values; if not, then setting to ¾ the value of
border-radius will work better.
border parameter must be set for this operation to be applied.