Small improvements and fixes

[phillipahereza]

Description

• [x] Added a fallback for the colorbewer option since embed charts do not pass the colorbrewer option

Type of change

Please delete options that are not relevant.

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

Screenshots

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation

[phillipahereza]

@kilemensi / @karimkawambwa need some help here, I can't get the iframe background to change