I do not seem to have a Vaadin .css in my web-inf directory. Where ias it?
The default stylesheets are all packaged inside the Vaadin JAR, and are served from there.
If you need a custom theme, then you need to create the folder and theme file yourseld inside the WebContent/VAADIN/themes folder.
(Edit: corrected the path, it shouldn't be WEB-INF/VAADIN. WebContent/VAADIN/themes is the correct place for custom themes)
来源：https://stackoverflow.com/questions/5594747/where-is-the-css-style-sheet-for-vaadin