Supple CSS: objects.aspect-ratio tests

.o-aspect-ratio

renders 1:1 (iframe)

renders 1:1 (img)

supports aspect ratio custom proptery (eg.: --ratio: (560/315))

.o-aspect-ratio--4by3

renders 4:3 (iframe)

renders 4:3 (img)

.o-aspect-ratio--16by9

renders 16:9 (iframe)

renders 16:9 (img)

.o-aspect-ratio--2by1

renders 2:1 (iframe)

renders 2:1 (img)