Fix bad img displaying on palette grid (center and fit)

[JonathanBytes]

Pull Request

Description

Fix the wrong image display on the palette grid. It wasn't fitting the image right and wasn't centered.

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] My changes generate no new warnings
• [x] I have checked my code and corrected any misspellings