A <resolution> measures pixel density in dpi, dpcm or dppx (dots per CSS pixel, alias x); 1x equals 96dpi. It appears in the density descriptors of image-set() (Image Values) and in the resolution media feature, whose value matches window.devicePixelRatio and therefore also changes with browser zoom: @media (resolution >= 2x) { .logo { background-image: url("logo@2x.png"); } }. The range syntax (>=) is Baseline widely available (in all engines since 2023). Older stylesheets write (min-resolution: 2dppx) or (-webkit-min-device-pixel-ratio: 2), which Safari 10 needed until version 16 (2022).