Nội dung1 GRADIENTS2 TOP - BOTTOM3 LEFT - RIGHT4 CENTER - CENTER5 LEFT - BOTTOM6 CENTER - BOTTOM7 SECTION VIGNETTING8 SECTION SMOOTH TRANSITION GRADIENTS Linear TOP - BOTTOM Linear LEFT - RIGHT Radial circle CENTER - CENTER Radial circle LEFT - BOTTOM Radial ellipse CENTER - BOTTOM Radial ellipse SECTION VIGNETTING Linear SECTION SMOOTH TRANSITION