Sticky

Example

A sticky header keeps the menu in reach while you read. A sticky sidebar that is too wide crowds the content on a phone.

Why it matters

Scrolling should not lose the map. Sticky means a sidebar or header that stays on screen while you scroll, helpful chrome, easy to overdo on a narrow phone screen.

In CSS this is position: sticky. A sticky element stays in the layout flow, unlike an overlay that sits on top of the page.