With document themes more specifically, we can change the overall colors, fonts and effects independently to the formatting and styles in a document. This works orthogonal to direct formatting and styles in a document. Until now in LibreOffice we only tried to preserve the theme information when working with a document, but from LibreOffice 7.6 on it will be possible to change the themes and also define new themes and use the theme colors in the opened document. There is a partial support already for Impress (which was also extended) and now the support is also available in Writer and Calc. In the talk I will present what document themes are and how the support for document themes was done.