Resize mode

Resize mode (Ctrl n) changes how much space the focused pane takes. The lowercase direction keys grow the pane toward that edge; the same keys shifted (uppercase) shrink it. There's also a non-directional pair for a quick bigger/smaller that lets Zellij decide the axis.

Ctrlthenn	Enter Resize mode
h	Increase size toward the left
j	Increase size downward
k	Increase size upward
l	Increase size toward the right
H	Decrease size on the left
J	Decrease size on the bottom
K	Decrease size on the top
L	Decrease size on the right
+	Increase (non-directional)
-	Decrease (non-directional)

You don't have to enter the mode for a quick adjustment. From Normal, Alt + (or Alt =) grows the focused pane and Alt - shrinks it, non-directionally. That covers most day-to-day resizing without a mode switch.

Altthen+	Increase focused pane size
Altthen-	Decrease focused pane size