CSS property: -webkit-mask-composite
    Description
Sets a compositing style for a mask.
The default value is border, which means that the background extends into the border area. Specifying a value of padding limits the background so that it extends only into the padding area enclosed by the border.
Syntax
-webkit-mask-composite: border | padding;
Values
- border (by default)
- The background extends into the border area. 
- padding
- The background extends only into the padding area enclosed by the border.