Replaced elements

The following are treated as replaced elements only in specific cases:

Replaced elements often have an intrinsic dimensions and intrinsic ratio. For example, the content of an <img> element is generally replaced by the image defined by its src attribute. That image has an intrinsic width and an intrinsic height specified in absolute units, which determines the aspect ratio.

Form controls are generally non-replaced widgets, except for <input type=”image”>, which is replaced with an image. Objects inserted using the CSS content property are anonymous replaced elements. They are “anonymous” because they don’t exist in the HTML markup.