An element’s back face is a mirror image of its front face. Though invisible in 2D, the back face can become visible when a transformation causes the element to be rotated in 3D space. (This property has no effect on 2D transforms, which have no perspective.)
/* Keyword values */
backface-visibility: visible;
backface-visibility: hidden;
/* Global values */
backface-visibility: inherit;
backface-visibility: initial;
backface-visibility: revert;
backface-visibility: revert-layer;
backface-visibility: unset;