Vaadin中创建的主题必须放置在VAADIN/themes 目录下。目录名称即为新的主题名称，新主题中必须包含一个styles.css 文件。新主题也必须继承某个Vaadin内置主题，如：
@import "../reindeer/styles.css";
.v-app {
background: yellow;
}
前面介绍的Vaadin个UI组件和布局都可以通过CSS 修改它们的显示外观。它们都定义了对应的Vaadin 的CSS类名，下表给出了Vaadin中标准UI组件的CSS类名：
| Server-Side Component | Client-Side Widget | CSS Class Name |
|---|---|---|
| AbsoluteLayout | VAbsoluteLayout | v-absolutelayout |
| Accordion | VAccordion | v-accordion |
| Button | VButton | v-button |
| CheckBox | VCheckBox | v-checkbox |
| CssLayout | VCssLayout | v-csslayout |
| CustomComponent | VCustomComponent | v-customcomponent |
| CustomLayout | VCustomLayout | v-customlayout |
| DateField | VDateField | v-datefield |
| VCalendar | v-datefield-entrycalendar | |
| VDateFieldCalendar | v-datefield-calendar | |
| VPopupCalendar | v-datefield-calendar | |
| VTextualDate | ||
| Embedded | VEmbedded | - |
| Form | VForm | v-form |
| FormLayout | VFormLayout | - |
| GridLayout | VGridLayout | - |
| Label | VLabel | v-label |
| Link | VLink | v-link |
| OptionGroup | VOptionGroup | v-select-optiongroup |
| HorizontalLayout | VHorizontalLayout | v-horizontallayout |
| VerticalLayout | VVerticalLayout | v-verticallayout |
| Panel | VPanel | v-panel |
| Select | ||
| VListSelect | v-listselect | |
| VFilterSelect | v-filterselect | |
| Slider | VSlider | v-slider |
| SplitPanel | VSplitPanel | - |
| VSplitPanelHorizontal | - | |
| VSplitPanelVertical | - | |
| Table | VScrollTable | v-table |
| VTablePaging | v-table | |
| TabSheet | VTabSheet | v-tabsheet |
| TextField | VTextField | v-textfield |
| VTextArea | ||
| VPasswordField | ||
| Tree | VTree | v-tree |
| TwinColSelect | VTwinColSelect | v-select-twincol |
| Upload | VUpload | - |
| Window | VWindow | v-window |
| - | CalendarEntry | - |
| - | CalendarPanel | v-datefield-calendarpanel |
| - | ContextMenu | v-contextmenu |
| - | VUnknownComponent | vaadin-unknown |
| - | VView | - |
| - | Menubar | gwt-MenuBar |
| - | MenuItem | gwt-MenuItem |
| - | Time | v-datefield-time |
Vaadin 内置了两种主题，reindeer 和 runo, Vaadin 6.0 缺省使用reindeer 主题。 有关主题定义的常数定义在包com.vaadin.ui.themes 中。
setTheme("runo");
Panel panel = new Panel("Regular Panel in the Runo Theme");
panel.addComponent(new Button("Regular Runo Button"));
// A button with the "small" style
Button smallButton = new Button("Small Runo Button");
smallButton.addStyleName(Runo.BUTTON_SMALL);
Panel lightPanel = new Panel("Light Panel");
lightPanel.addStyleName(Runo.PANEL_LIGHT);
lightPanel.addComponent(new Label("With addStyleName(\"light\")"));
Vaadin 的Eclipse插件可以帮助创建新主题，为项目添加一个新主题. New -> Other -> Vaadin -> Vaadin theme
按照向导一步一步，就可以创建一个新的主题，然后修改新主题下的styles.css ，就可以达到自己预期的显示效果。