Cheap-n-cheerful theme

The application name (as defined by causeway.viewer.wicket.application.name) is also used in sanitized form as the CSS class in a <div> that wraps all the rendered content of every page.

For example, if the application name is "ToDo App", then the <div> generated is:

<div class="todo-app">
    ...
</div>

You can therefore use this CSS class as a way of building your own "theme" for the various elements of the wicket viewer pages.

Alternatively you could "do it properly" and create your own Bootstrap theme, as described in the extending chapter.