Deck UI is one of the available UIs in Misskey. It is characterized by the ability to build highly customizable and informative UIs by displaying multiple views, called "columns", side by side. The deck option is only available on sufficiently large screens like a laptop computer.
You can add a column by right-clicking on the deck background and selecting "Add Column". You can also click the '+' icon on the right side of the screen.
Columns can be repositioned by drag-and-drop or by using the column menu "Move" option (right-click on the column header).
Horizontal Division of Columns
Columns can be arranged vertically as well as horizontally. Open the column's menu and select "Stack with the left column" to move the current column below the column to its left. To unstack a column, select "Pop column to the right" from the column's menu.
Configure Column Layout
Select "Column settings" in the column menu to edit column layout settings. Here you can change the column name and width. If the colum is set to flexible then it will expand beyond its set width to fill remaining horizontal space on the screen.
Deck-related settings can be changed in the settings menu (click the gear icon in the bottom right of the screen.
You can create/load a deck profile by clicking on the menu in the top right of the screen. Choose "New profile" to create a new blank deck to customize. Select another profile to switch to it. The trash button deletes the current profile.