Web, documents and technology
CSS pixel
In short and in plain language
A CSS pixel is a unit for sizes on web pages.
The browser uses it to work out widths and spacing. It is not necessarily the same as a dot on the screen.
The rules for accessibility give sizes in this unit. One example is the size of buttons.
Definition
A CSS pixel is the unit browsers use to calculate sizes and spacing on web pages. It does not necessarily match a physical pixel of the screen; on high-resolution displays it covers several. WCAG states the minimum size of click targets and the width for reflow when zooming in CSS pixels.