AE2 GUI Resource Pack only changes the interface. Your blocks, items and mobs keep their normal look, so turning it on will not change anything in your world.
Activate the pack
1. From the title screen or the pause menu, open Options and then Resource Packs.
2. Find AE2 GUI Resource Pack in the Available list on the left.
3. Click the arrow on its icon to move it into the Selected list on the right.
4. Click Done. The game reloads its assets, which can take a moment.
If the pack is not in the Available list, click Open Pack Folder. Check that the pack file is in the resourcepacks folder that opens, then close and reopen the Resource Packs screen.
Confirm it worked
- Press your inventory key, which is E by default. The vanilla inventory should now show a clean tech design with a white, unified look.
- Go back to Options. The buttons should have the new styling too, because the pack restyles buttons across the whole interface.
- Open any screen with a typing field, such as the world name box on the world creation screen. Text boxes are restyled to match the theme.
If your inventory still looks vanilla, see the troubleshooting guide on fixing menus that keep the default look.