SharePoint Online Custom Theme No Customize

[NotAlex]

I am trying to create a custom theme with the "strong" background type.

However There is no customize button on custom theme and I do not see any json schema property for it.

Does anyone know if this is possible?

Thanks

[#2 · Accepted solution]

If anyone is interested, there is a new web property in the latest version of csom

• public property Microsoft.SharePoint.Client.Web.HeaderEmphasis

So setting this via code allows a custom theme to be used with a strong background

e.g. context.Web.HeaderEmphasis = SPVariantThemeType.Strong;