You can easily change themes and colours of the webpart via Settings - Change the look – Themes in the top right corner.
Please note that you need to be a site owner to change the site look.
To learn more on how to customize the site look navigate to Change the look of your SharePoint site.
To get most out of LMS365 we recommend using SharePoint default dark and light themes as we fully support their readability. Once you have customized themes, we do not guarantee the readability of statuses.
SharePoint standard dark theme:
If you still want to customize themes, we recommend you trying it first to ensure that the colours of statuses are readable.