Everything is immutable in ScalaCSS (except for the small scalacss.internal.mutable package), so any StyleS, StyleF, StyleC can safely be used anywhere else.

StyleA (applicable inline style) is immutable too but one of its properties is a generated class name. If you're using inline stylesheet, class names are generated by StyleSheet.Register so sharing them is not a good idea. Instead what you want is a reusable style module.

Style Modules

It's often preferable to share a collection of named styles, a style module.

The definition of a style module is only slighty different from normal stylesheets in that instead of defining an object

object MyStyles extends StyleSheet.Inline {

you create a class with an implicit register

class MyStyleModule(implicit r: StyleSheet.Register) extends StyleSheet.Inline()(r) {

Note: The ()(r) syntax is weird because Scala has a rule that implicit arguments always come second, even when there are no non-implicit arguments. That is the case here which is why it forces us to specify an empty argument list before setting the implicit one.

To use shared styles, you simply create an instance of them inside another stylesheet.

object MyStyles extends StyleSheet.Inline {
  val shared = new MyStyleModule

That's all there is to it.


A shared module:

class SharedTheme(implicit r: StyleSheet.Register) extends StyleSheet.Inline()(r) {
  import dsl._

  val button = style(
    padding(0.5 ex, 2 ex),
    border(1 px, solid, black)

  val title = style(
    fontSize(32 px)

Concrete styles in the app:

object MyAppStyles extends StyleSheet.Inline {
  import dsl._

  val theme = new SharedTheme // Instantiate shared styles

  val headingTitle = style(
    theme.title,              // Extend shared style

Example usage in scalajs-react:

def showDetailsButton =
    ^.onClick ~~> showLoginDetails(user),
    "Show Details"))

def render =
      "Your Login Details"),

If you're writing a shared library, then we tweak the above snippet so that the sharable style is passed in.

def showDetailsButton(theme: SharedTheme) =
    ^.onClick ~~> showLoginDetails(user),
    "Show Details"))

If you don't want to pass a stylesheet around, see Global Registry.