Frontend & browser·Layout, CSS and the cascade
the heading scrolls with the page until it reaches the top, then stays there until its section ends.
Sticky positioning
Also calledposition: sticky
A hybrid that behaves as relative until a scroll threshold is crossed and as fixed after it, bounded by the nearest scrolling ancestor. It needs an offset — a `top` value with no unit at all does nothing — and it silently fails if any ancestor has `overflow: hidden` or `auto`, which is the reason nine out of ten sticky bugs happen. It sticks within its parent, so a short parent ends the effect early.