Using CSS Variables
Hilla apps typically use either the Lumo or Aura theme as a base for component and application styling. Both themes are based on a set of CSS custom properties that you can use to achieve a consistent look and feel across applications.
You can use these properties in place of hard-coded units using var().
Source code
CSS
.card {
border: 1px solid var(--lumo-contrast-30pct);
border-radius: var(--lumo-border-radius-s);
box-shadow: var(--lumo-box-shadow-s);
}The Styling section provides more information about styling Vaadin applications.