Presets and geometry

On a configuration with no saved layouts, Grid Screen seeds these five presets. Each starts with a 10px gap and 16px margin.

Preset	Zones	Shape
Two Columns	2	Equal columns, ratio 50
Three Columns	3	Equal columns
Focus + Stack	3	Two-thirds left pane, two stacked right panes
Main + Sidebar	2	Three-quarters main pane, ratio 75
3 Wide Center	3	Equal-width geometry in the current engine

The layout engine subtracts outer margins and inter-zone gaps from the screen work area. Two-zone layouts with a ratio use that ratio. A three-zone layout with rows uses the Focus + Stack geometry. All other layouts use equal-width columns based on the zone count.

The engine currently does not use every saved column string as geometry input. In particular, its equal-column fallback means 3 Wide Center is persisted with 1fr 2fr 1fr but is not rendered as a wider center zone by the Rust geometry calculation.