box-sizingThe box-sizing CSS property sets whether an element's width and height are calculated based on the content-box, which does not count the size of borders or padding, or border-box, which does count them.layoutLayoutwidely2015-07-292018-01-29https://drafts.csswg.org/css-sizing-3/#propdef-box-sizingcss3-boxsizinghttps://developer.mozilla.org/docs/Web/CSS/Reference/Properties/box-sizingcss.properties.box-sizingcss.properties.box-sizing.border-boxcss.properties.box-sizing.content-boxhttps://nowyoucanuse.com/features--box-sizing.html