Note 2 Content identified as " informative " or "non-normative" is never required for conformance . on a full-screen window on the most common sized desktop/laptop display with the viewport maximized Note Since people generally keep their computers for several years, it is best not to rely
      on the latest desktop/laptop display resolutions but to consider the common desktop/laptop
      display resolutions over the course of several years when making this evaluation. paused stopped by user request and not resumed until requested by user perimeter [New] continuous line forming the boundary of a shape not including shared pixels, or the minimum bounding box , whichever is shortest. Example The perimeter calculation for a 2 CSS pixel perimeter around a rectangle is 4 h +4 w , where h is the height and w is the width. For a 2 CSS pixel perimeter around a circle it is 4𝜋 r .