When focus order stops matching the page

Briefing

Why can a visually ordered row of controls be traversed in a different order by the keyboard, and what actually determines the sequence?

The layout reads left to right. The Tab key does something else entirely, and CSS is the reason.

Laboratory

Accessibility Lab

Level

ENGINEER

Estimated time

8 minutes

Method

interactive

Variables under observation

focus ordertabindexflex orderaccessibility treekeyboard