Combining Recolourful Containers With Other Resource Packs Safely
Most players run several packs at once, and UI packs are the most likely to overlap. Here is how to stack them without losing the recolored containers you installed this pack for.
Understand the overlap
Resource packs override individual textures. Recolourful Containers edits container GUIs and HUD art. Any other pack that also edits those same files will compete, and only the topmost one shows. Packs that only change blocks, items, or sounds will not conflict with it at all, so you can leave those wherever they are.
Build your order deliberately
In Options, then Resource Packs, arrange the Selected column from most specific to least. Put packs you want to win at the top. If a full UI overhaul is your priority, it goes above Recolourful Containers. If the recolored containers are your priority, Recolourful Containers goes above the overhaul. Keep unrelated packs below both.
Test and iterate
Apply, then open a chest, a furnace, and your inventory to confirm the look. If something reverts, move the relevant pack one slot and retest rather than shuffling everything at once. Once you find an order you like, leave it alone, since resource pack order persists between sessions and only needs setting up once.