v1.6 left the Workspace's Split-button row visible on mobile even when only one pane was open — ~36px of dead chrome above the chat. Wrap the entire Split-row in !isMobile so mobile gets header → chat with no intermediate strip. The existing mobile pane-navigator strip (gated to panes.length > 1) is unchanged and still appears once a second pane is created via the long-press "New chat" menu item (G3).