pt versus px

visual test to demonstrate that 1pt = 1.333px as per CSS Values and Units Module Level 3 - 5.2. Absolute lengths.

as 1pt = 1/72th of 1in and 1px = 1/96th of 1in, 1pt = (96/72)px = 1.333px

as an additional exercise, take a ruler and measure the actual physical size the pt blocks are being rendered at on your particular screen, and see if they match their actual real-world measurement (hint: the 72pt block should be 1in wide/high if that was the case). They won't, or at least can't be guaranteed to be across devices, as pt and other "physical" units are in fact anchored on the reference px and will vary depending on all sorts of factors, such as actual screen size, screen resolution, viewport settings, browser settings, OS settings, user settings, etc.

note that this page uses <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"> to force an "ideal" viewport.