Focus Borders

Mosaico draws a colored border overlay around the currently focused window, making it easy to identify which window has focus.

Configuration

Border settings are in config.toml:

[borders]
width = 4              # Border thickness in pixels (0-32)
corner_style = "small" # "square", "small", or "round"
focused = "#00b4d8"    # Color for focused window
monocle = "#2d6a4f"    # Color for monocle mode

• width – thickness of the border in pixels. Set to 0 to disable the focus border entirely.

• corner_style – controls both the border overlay shape and the DWM corner preference for tiled windows (Windows 11 only; ignored on Windows 10).

  Value	Border overlay	DWM (Windows 11)
  "square"	Sharp corners (0 px)	DONOTROUND
  "small"	Subtle rounding (8 px)	ROUNDSMALL (~4 px)
  "round"	Standard rounding (16 px)	ROUND (~8 px)

• focused – the border color during normal tiling. Accepts hex colors or named Catppuccin colors (see Theming).

• monocle – the border color when monocle mode is active.

Behavior

• The border automatically follows focus as you navigate between windows
• It is a click-through overlay that does not interfere with your interaction with the focused window
• The border sits on top of all windows (topmost)
• It is excluded from tiling (it is invisible to the tiling manager)

Using Named Colors

With a theme active, you can use named colors:

[borders]
focused = "blue"
monocle = "green"

Hot-Reload

Border settings are hot-reloaded. Changes to width, corner_style, focused, and monocle colors take effect immediately.