Styling Annotations

@Style (Target: TYPE, FIELD, PARAMETER)

public @interface Style {
  String value();  // inline CSS string
}

Applies inline CSS to the component’s root element. Applied on a class, styles the page container.

Example from the demo:

@UI("/home")
@Style("max-width: 900px; margin: auto;")
public class Home { ... }

@CssClasses (Target: TYPE, FIELD, PARAMETER)

public @interface CssClasses {
  String value();  // space-separated class names
}

Adds CSS class names to the component’s root element.

@DivStyle (Target: TYPE, FIELD, PARAMETER)

public @interface DivStyle {
  String value();  // inline CSS string
}

Applies inline CSS to the wrapper <div> around the element, rather than the element itself. Useful when you need to style the layout container rather than the component.

@Compact (Target: TYPE)

public @interface Compact {}

Renders a page in high-density mode: tighter control sizes, smaller spacing, and compressed field labels so information-dense screens fit without scrolling. Implemented by injecting the StyleConstants.COMPACT CSS custom-property block onto the page container. Because CSS custom properties cascade through shadow DOM, every Vaadin/Lumo component inside is condensed automatically. Font size is intentionally left at the standard Lumo value so text stays legible.

In addition to the visual change, @Compact reduces the auto-responsive form-layout minimum column width to 7em (vs the standard default), so more columns fit at the same viewport width. On grids and tables the flag also applies Vaadin’s built-in compact row density theme.

@UI("/checkin/:id")
@Compact
@Style(StyleConstants.FULL_WIDTH_WITH_PADDING)
@Zones({
    @Zone(name = "left",  width = "64%"),
    @Zone(name = "right", width = "36%")
})
public class CheckInForm { ... }

@Compact is opt-in and non-breaking — pages without it are unaffected.

If you need compact density on only part of a page, or want to blend it with other constants, use @Style(StyleConstants.COMPACT) directly on the narrower element.

StyleConstants

Mateu provides a StyleConstants class with predefined style values:

Constant	Effect
StyleConstants.CONTAINER	Centers content with max-width: 900px
StyleConstants.FULL_WIDTH	Sets width: 100%
StyleConstants.FULL_WIDTH_WITH_PADDING	Full width with 2rem horizontal padding
StyleConstants.COMPACT	High-density Lumo preset (used by @Compact)

// Common usage
@Style(StyleConstants.CONTAINER)           // centers content with max-width
@Style(StyleConstants.FULL_WIDTH_WITH_PADDING)  // full-width with padding

Difference between @Style and @DivStyle:

Annotation	Styled element
@Style	The component element itself
@DivStyle	The outer wrapper div