private String getPrismThemeClassName() {
        final ThemeType themeType = userPreferencesManager.geCurrentThemeType();
        switch (themeType) {
            case DARK:
                return "";
            case LIGHT:
                return PRISM_LIGHT_THEME_CLASS_NAME;
            default:
                throw new RuntimeException("Unexpected theme type " + themeType);
        }
    }
@return The space separated list of css classes to set on the container div that holds
the markdown html.
stroom-core-client/src/main/java/stroom/entity/client/presenter/MarkdownConverter.java