Each category accordion header has a checkbox which should check all (if checked) or deselect all (if unselected). Its state should also be synced to the state of its children, using an interstitial (neither checked or unchecked) state if only some children are checked.
Each category accordion header has a checkbox which should check all (if checked) or deselect all (if unselected). Its state should also be synced to the state of its children, using an interstitial (neither checked or unchecked) state if only some children are checked.