Stretch and scale a CSS image in the background - with CSS only

Question

I want that my background image stretch and scale depending on the browser viewport size.

I\'ve seen some questions on Stack Overflow that do the job, like

Answer 1

You can actually achieve the same effect as a background image with the img tag. You just have to set its z-index lower than everything else, set position:absolute and use a transparent background for every box in the foreground.