The transparency level of tiles can be set by clicking on Edit Tiles in the top left of your Tiles dashboard, selecting Change Background to bring up the Background Settings menu, and clicking the Advanced menu. The transparency level is under the Tile Color option. Click the Tile Color box and move the bottom slider to set the transparency level. As the slider moves, the transparency level will update to preview your changes. Tiles can be made completely transparent by sliding the transparency slider all the way to the left.