A fitted backpack
Inventory cells use the available space, with vacant slots completing the visible grid.
Backpack, storage, jewels, materials and batch selection now fill their visible grid with occupied and vacant slots. Cells grow moderately to absorb unused bands along the edges, keeping the inventory consistent on desktop and phone screens.
Showing the free spaces on a page does not create extra empty browsing pages or increase your capacity. Saved item positions, Auto arrange, filters and manual movement retain their existing rules. Receiving another item inside the current page also keeps its grid size steady.