This has now been fixed in version 1.3.1. In your editor module's get_field(...) function, you can use this code to add a style sheet:
This assumes that you included $this->urltoroot=$urltoroot; in your module's load_module(...) function and that your CSS is in styles.css.
Be sure to set Plugin Minimum Question2Answer Version to 1.3.1 in your qa-plugin.php file, since this method won't work in 1.3!
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.