Black & White chart blocks

[papjul]

Describe the bug
Sometimes between 4bf28a5 and v1.6.1, charts added as blocks on pages became colorless.
Issue did not happen in previous version or when #59 was submitted

To Reproduce
Pre-requisite:
Modules:

• default pedigree chart from Webtrees must be disabled
• webtrees-pedigree-chart must be enabled

Steps to reproduce the behavior:

1. Go to homepage tree
2. Add a chart block of type "Pedigree"
3. Come back to homepage
4. See chart in black and white

Expected behavior
Chart should be colored.

Screenshots

Desktop (please complete the following information):

• Browser: Chrome, Firefox
• Webtrees version: 2.1.18
• Version of pedigree chart: 1.6.1

Additional context
Real-life example here: https://gene.amenysta.net/tree/papasian

[magicsunday]

The only drawback of the solution is now, multiple includes of the CSS files, but there seems to be no other way to solve it in Webtrees at the moment.

fisharebest/webtrees#4908