Round a CSS stroke width to a whole number of device pixels (minimum 1 device
pixel), returned in CSS pixels.
A fractional device-pixel width (e.g. a 1px CSS stroke at a 1.5 dpr) cannot
render crisply - the browser anti-aliases it, and the result drifts as the dpr
changes. Rounding to whole device pixels keeps the stroke crisp at any dpr.
Round a CSS stroke width to a whole number of device pixels (minimum 1 device pixel), returned in CSS pixels.
A fractional device-pixel width (e.g. a 1px CSS stroke at a 1.5 dpr) cannot render crisply - the browser anti-aliases it, and the result drifts as the dpr changes. Rounding to whole device pixels keeps the stroke crisp at any dpr.