The roof assembly includes guide rails extending parallel and at a distance from each other. The guide rails each include a guide groove being defined between an upper and lower flange of the guide rails. The guide grooves open in a direction towards each other, and further comprise at least one closure panel, in particular a sunshade panel, having two opposite sides substantially parallel to the guide rails and each including at least two laterally projecting tabs for engagement into the respective guide groove. At least one of said lower and upper flanges of each guide rail has at least one cut-out for allowing the tabs of the closure panel to enter the guide groove.