Inches in css aren't in any way related to physical inches. CSS has no knowledge of your physical screen dimensions. Rather an inch was defined early on in the

Inches in css aren't in any way related to physical inches. CSS has no knowledge of your physical screen dimensions. Rather an inch was defined early on in the history of css as "1 inch in pixels of a 17 inch screen at 1280x1024 resolution" This happens to be 96.42 pixels, which rounded down to 96. So not only is it an obscure unit, it's also a misleading one. On your 4k monitor 96 pixels is more than likely not an inch (unless your monitor is slightly over 42 inches), so it wont solve your small app problem in any form, it will just make things more obscure. In addition to this, you'll also end up with many subpixel values. While this wont matter for 𝚋𝚘𝚛𝚍𝚎𝚛 in the example I posted above (as border always snaps to the nearest dp unit), it will create blurry effects on lower DPI screens for other css rules that do respect subpixel values (i.e. 𝚋𝚘𝚡-𝚜𝚑𝚊𝚍𝚘𝚠: 𝟶 𝟶 𝟶 𝟶.𝟸𝚒𝚗 #𝟶𝟶𝟶; will create a blurred border effect).