An appliance includes a cabinet having outer walls that define a portion of a contact surface. Operable panels are engaged with the cabinet and operate between closed and open positions. A lateral mullion is pivotally attached to a mullion panel of the plurality of operable panels and is operable between contact and tucked positions. When the mullion panel is in the closed position, an outer surface of the lateral mullion is in the vertically pointed contact position and defines a portion of the contact surface to receive a seal of the mullion panel and selectively receive a seal of a vertically adjacent panel. Movement of the mullion panel to the open position rotates the lateral mullion about a horizontal axis to define the tucked position such that the mullion panel can move to the open position free of operation of the vertically adjacent panel.