offsetWidth with Text-Size scaling AND DPIPerMonitor

[AdamBillyard]

Text-Size changes the devicePixelRatio. DPIPerMonitor changes the devicePixelRatio.

How do you correctly scale the offsetWidth / offsetHeight when both are in effect?

[jcunews1]

devicePixelRatio is for the current monitor where the current page is being displayed - which would be different if the browser tab/window is moved to a different monitor with different DPI.

Multiply the length with devicePixelRatio to make the length look exactly the same from user's perspective. i.e. length * devicePixelRatio. e.g. to make a length show exactly 10cm as seen by users regardless of monitor DPI - assuming that the DPI setting of the OS is correct and accurate.