Creating and Using Themes

You can use Sass themes in Vaadin in two ways, either by compiling them to CSS by yourself or by letting the Vaadin servlet compile them for you on-the-fly when the theme CSS is requested by the browser, as described in “Compiling Sass Themes”.

To define a Sass theme with the name mytheme, you must place a file with name styles.scss in the theme folder VAADIN/themes/mytheme. If no styles.css exists in the folder, the Sass file is compiled on-the-fly when the theme is requested by a browser.

We recommend that you organize the theme in at least two SCSS files so that you import the actual theme from a Sass file that is named more uniquely than the styles.scss, to make it distinquishable in the editor. This organization is how the Vaadin Plugin for Eclipse creates a new theme.

If you use Vaadin add-ons that contain themes, Vaadin Plugin for Eclipse and Maven automatically add them to the addons.scss file.

We recommend that the rules in a theme should be prefixed with a selector for the theme name. You can do the prefixing in Sass by enclosing the rules in a nested rule with a selector for the theme name.

Themes are defined as Sass mixins, so after you import the mixin definitions, you can @include them in the theme rule as follows:

CSS

However, this is mainly necessary if you use the UI in portlets, each of which can have its own theme, or in the special circumstance that the theme has rules that use empty parent selector & to refer to the theme name.

Otherwise, you can safely leave the nested theme selector out as follows:

CSS

@import "mytheme.scss";
@include addons;
@include mytheme;

The actual theme should be defined as follows, as a mixin that includes the base theme.

@import "../valo/valo.scss";
@mixin mytheme {
  @include valo;
  /* An actual theme rule */
  .v-button {
    color: blue;
}

Add-on Themes

Some Vaadin add-ons include Sass styles that need to be compiled into the theme. These are managed in the addons.scss file in a theme, included from the styles.scss. The addons.scss file is automatically generated by the Vaadin Plugin for Eclipse or Maven.

In addition to Sass themes, you can create plain old CSS themes. CSS theme are more restricted than Sass styles - you can’t parameterize CSS themes in any way, unlike you can Valo, for example. Further, an application can only have one CSS theme while you can have multiple Sass themes.

A CSS theme is defined in a styles.css file in the VAADIN/themes/mytheme folder. You need to import the legacy-styles.css of the built-in theme as follows:

@import "../reindeer/legacy-styles.css";
.v-app {
    background: yellow;
}

Each user interface component in Vaadin has a CSS style class that you can use to control the appearance of the component. Many components have additional sub-elements that also allow styling. You can add context-specific stylenames with addStyleName(). Notice that getStyleName() returns only the custom stylenames, not the built-in stylenames for the component.

Please see the section on each component for a description of its styles. Most of the style names are determined in the client-side widget of each component. The easiest way to find out the styles of the elements is to use a HTML inspector such as FireBug.

Some client-side components or component styles can be shared by different server-side components. For example, v-textfield style is used for all text input boxes in components, in addition to TextField.

Vaadin currently includes the following built-in themes:

• valo, the primary theme since Vaadin 7.3

• reindeer, the primary theme in Vaadin 6 and 7

• chameleon, an easily customizable theme

• runo, the default theme in IT Mill Toolkit 5

In addition, there is the base theme, which should not be used directly, but is extended by the other built-in themes, except valo.

The built-in themes are provided in the respective VAADIN/themes/<theme>/styles.scss stylesheets in the vaadin-themes JAR. Also the precompiled CSS files are included, in case you want to use the themes directly.

Various constants related to the built-in themes are defined in the theme classes in com.vaadin.ui.themes package. These are mostly special style names for specific components.

@Theme("runo")
    @Override
    protected void init(VaadinRequest request) {
        ...
        Panel panel = new Panel("Regular Panel in the Runo Theme");
        // 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\")"));
        ...

The example with the Runo theme is shown in Runo Theme.

Runo Theme

The built-in themes come with a custom icon font, FontAwesome, which is used for icons in the theme, and which you can use as font icons, as described in .

Creation of a default theme for custom GWT widgets is described in “Styling a Widget”.

The add-on themes need to be included in the project theme. Vaadin Plugin for Eclipse and Maven automatically include them in the addons.scss file in the project theme folder. It should be included by the project theme.