Mosaic Tiles can be organized on a grid up to 4 columns wide. Each tile can be full width or in halves, thirds, or quarters of a row.
While in Edit mode, press Alt key on your keyboard to enter Advanced mode. It will allow you to see the boundaries of the rows and tiles, labels for the tiles, and css classes for the rows. To exit Advanced more, press Alt again.
Also in the advanced mode, you’re able to add custom classes on rows.
In order to nest columns inside a cell, drag a tile, then press the Ctrl key and drop the tile close to an existing one, either before or after it, in accordance to the shown insert marker.
For fluid (full width) rows select any tile in the row and choose “Fluid” from the “Format” menu. Fluid row styles works best on pages without portlets.