This is the meta bug to track the implementation of the new combined highlighters feature. Elements in the page often get highlighted in devtools: - when you click on the element picker icon in the toolbox and then hover over elements in the page, - or you move your mouse over elements in the inspector tree, - or move your mouse over elements in the animation inspector, or console, - or click on the inspector icon in the rule-view next to selectors, - ... All of these, today, end up toggling the box-model highlighter on the hovered/selected elements, which is useful because you see how big elements are, how big their margins are, etc. This feature is about combining the box-model highlighter with the flex and grid highlighters, so that when you do any of the above actions, and the hovered/selected element is a grid or flex container or item, then the grid or flex highlighters get displayed too. This way, users can quickly see what type of layout various elements use.