In a fixed layout, the size of the page and the size of the page elements are fixed using as the unit of measure.

Pixel is the correct answer for the above question.

Explanation:

Pixel is the primary unit to measure any picture or video in the computer system. So when a user wants to do the coding in HTML language and if he needs to specify any size then he will give the size with the help of pixel, for example, 5px or 10px. (whereas px stands for pixel).

So we can say that the measurement size of the page and the element of the HTML content is the pixel. which fills the question statement because the question asked about the measurement unit of the page and the HTML content.