You are right!
Click View > Pods > Topic List.
Click on one topic to place focus there.
Select all topics in the pod by pressing Ctrl+A
Right-click the selection and choose Properties.
Click the Appearance tab and choose the style sheet you wish to associate with all the selected topics.
Helpful and Handy Links
While talking about assigning .css to every topic .... every time a create a new topic, it fails to get my custom .css. I have to open the html and type the name of the .css into the code. How to I make sure all new topics pick up the custom style sheet?