Backpack Borders is a small UI tweak that adds a background and border to the container buttons in Zomboid's inventory windows.
The change makes it easier to see each individual button, particularly when the player is using dark coloured backpack items, such as a black duffel bag.
This tool allows you to freely draw lines of any shape. You can customize how thick and filled out the line is, allowing for bold full lines, thin dotted lines, and everything in-between!