What is fixed positioned relative to?

The position: fixed value in CSS positions an element relative to the browser window (viewport), not relative to parent elements or the document. This means that the element remains in the same place on the screen when scrolling the page.

For example, if a block is set with position: fixed; top: 0; right: 0;, it will always be fixed in the top right corner of the browser window, regardless of page scrolling.