box-shadowThe box-shadow CSS property applies shadow effects around an element's frame. This can create drop shadow and inner shadow effects.backgroundBackgroundwidely2015-07-292018-01-29https://drafts.csswg.org/css-backgrounds-3/#box-shadowcss-boxshadowhttps://developer.mozilla.org/docs/Web/CSS/Reference/Properties/box-shadowcss.properties.box-shadowcss.properties.box-shadow.insetcss.properties.box-shadow.multiple_shadowscss.properties.box-shadow.nonecss.properties.box-shadow.spread_radiushttps://nowyoucanuse.com/features--box-shadow.html