There may, however, be some further adjustments between a "physical" pixel and an on-screen logical pixel. As screens are viewed at difference distances (consider a phone, a computer display, and a TV), the desired length (a "reference pixel") is scaled relative to a reference viewing distance ( in CSS). In addition, as true screen pixel densities are rarely multiples of 96 dpi, some rounding is often applied so that a logical pixel is an integer amount of actual pixels. Doing so avoids render artifacts. The final "pixel" obtained after these two steps becomes the "anchor" to which all other absolute measurements (e.g. the "centimeter") are based on.
there may however be some further adjustments between a "physical" pixel and an on-screen logical pixel as screens are viewed at difference distances (consider a phone a computer display and a tv) the desired length (a "reference pixel") is scaled relative to a reference viewing distance ( in css) in addition as true screen pixel densities are rarely multiples of 96 dpi some rounding is often applied so that a logical pixel is an integer amount of actual pixels doing so avoids render artifacts the final "pixel" obtained after these two steps becomes the "anchor" to which all other absolute measurements (eg the "centimeter") are based on