Curled Corners (Paper)

.curled_corners_top_left

.curled_corners_top_right

.curled_corners_top

.curled_corners_bottom_left

.curled_corners_bottom_right

.curled_corners_bottom

Only one ::before and only one ::after pseudo selector per element, therefore no _all, nor _left, nor _right, as they'd all require multiple ::before and/or ::after selectors.
CSS style is .curled_corners_{top,bottom}[_{left|right}]
Beware issues with z-index on the parent .container class. In the "all" page, the parent container required a z-index: 0; to allow mouse events to fire. pointer-events CSS didn't (seem to) help.