If you want to generate, great looking serious documents with no CSS hassle have a look at Word merge for Mendix. It's a perfect solution for generating complex document while using Word as your template editor.
See also this blog
Alternatively, you can also work in Word and have a seamless interface to the Exari DocGen product via the Word Document Generation for Mendix app in the app store.
See also this blog:
Or you could try out the new module of Eric Tieniber on Github: https://github.com/tieniber/PDF-Exporter In this module you create a pdf form where the fields are filled by Mendix.