dark theme has issues with charts on demo

[WEBhicham]

Issue type

• bug report
• feature request
• question about the decisions made in the repository

Issue description

Current behavior:
On the demo the dark theme has issues with chart colors (see printscreens)

Expected behavior:
choose dark theme on the demo and see charts disappear :D

Steps to reproduce:
having nice looking charts

well, see Current behavior

Other information: