New theming for additional SharePoint Online site templates

[How does this affect me?]
After the rollout is complete, the new site theming experience will be available on classic site templates. A new site theming panel will be available, empowering site owners to easily apply one of the new themes to all pages of the site by selecting the theme of their choice.

Classic sites that do not use SP JavaScript will render un-themed if the site theme is changed. If you would like to maintain custom themes on classic sites, as administrator, you can opt out of the new theming experience by using Microsoft PowerShell.

We’ll be gradually rolling this out to Targeted Release organizations in early April, and we anticipate rollout completion in early May.

[What do I need to do to prepare for this change?]
If you wish to take advantage of the new SharePoint Online site theming, there is no action you need to take. The new setting will show up in the site settings gear menu as “Change the look” for each site.

If you change the theme for a site and notice any issues, you can opt out of the change by using Microsoft PowerShell, and re-apply any themes that were changed.

To learn more about the option to opt-out, please click here.
For more information on SharePoint Online site theming, please click Additional Information below.