@yak/solid Copy package name

@yak/solid

Styled-components syntax for SolidJS, compiled away at build time. Your CSS is extracted by the yak SWC compiler and what's left at runtime is a thin layer that fits Solid's model: components run once, and dynamic styles are driven by signals, not re-renders.

Status: experimental. @yak/solid targets Solid 2 (currently at RC) and tracks it closely. Expect breaking changes while Solid 2 stabilizes. Solid 1 is not supported, and neither is SolidStart v2, which still runs on Solid 1.

Why this fits Solid

Most CSS-in-JS libraries assume a re-rendering component model. @yak/solid doesn't. It works the way you'd expect Solid code to work:

• Static styles are just classes. A styled.div with no interpolations compiles to a plain CSS class and a single reactive class binding.
• Dynamic styles are signals in, CSS variables out. Interpolations like ${(props) => props.$angle} become CSS custom properties on the element's inline style. All of them are computed in one memo per component. When a prop changes, the element is not re-created, only its class/style bindings update, and the memo only re-runs for props the CSS actually reads.
• No hidden subscriptions. Reads inside interpolations are tracked like any other reactive read in Solid. If your CSS doesn't read props.theme(), it doesn't subscribe to the theme.

Getting started

pnpm add @yak/solid
pnpm add -D @solidjs/vite-plugin@next

Add the yak plugin before solid() in your Vite config:

// vite.config.ts
import { defineConfig } from "vite";
import solid from "@solidjs/vite-plugin";
import { yak } from "@yak/solid/vite";

export default defineConfig({
  plugins: [yak(), solid()],
});

For server rendering, bundle Solid together with @yak/solid or keep both external. Solid 2 ships a development export condition, so an app that lists only @yak/solid under ssr.noExternal ends up with two copies of Solid on the server and context lookups fail:

ssr: { noExternal: ["@yak/solid", "solid-js", "@solidjs/web", "@solidjs/signals"] },

Then write styled components the way you'd write them anywhere else. Prop-based interpolations are tracked reactively:

import { styled, css, keyframes } from "@yak/solid";

const Button = styled.button<{ $primary?: boolean }>`
  color: #009688;
  ${(props) =>
    props.$primary &&
    css`
      border-width: 2px;
    `}
`;

const Hand = styled.div<{ $angle: number }>`
  transform: rotate(${(props) => props.$angle}deg);
`;

The css prop works on every intrinsic element and maps to Solid's class attribute:

<p
  css={css`
    color: green;
  `}
/>

Theming

Create a yak.context.ts next to your vite.config.ts (picked up automatically) and augment the YakTheme interface:

export function getYakThemeContext() {
  return { highContrast: false };
}

declare module "@yak/solid" {
  export interface YakTheme extends ReturnType<typeof getYakThemeContext> {}
}

useTheme() returns an accessor, like a signal getter. Call it where the value is used. That read is what subscribes the surrounding scope to theme changes:

import { styled, useTheme, YakThemeProvider } from "@yak/solid";

const Button = styled.button`
  color: ${(props) => (props.theme().highContrast ? "#000" : "#555")};
`;

function Toolbar() {
  const theme = useTheme();
  return <span>{theme().highContrast ? "High contrast" : "Default"}</span>;
}

// app root: the theme prop is reactive, signal reads inside it stay live
<YakThemeProvider theme={{ highContrast: highContrast() }}>
  <App />
</YakThemeProvider>;

The theme context itself is exported too, so you can compose it natively, e.g. to override the theme for a subtree. In Solid 2 a context is its own provider and takes an accessor:

import { createMemo } from "solid-js";
import { YakThemeContext, useTheme } from "@yak/solid";

function InvertedSection(props) {
  const parent = useTheme();
  const inverted = createMemo(() => ({ ...parent(), highContrast: true }));
  return <YakThemeContext value={inverted}>{props.children}</YakThemeContext>;
}

Coming from next-yak or React?

If you've used next-yak, the API is the same with a few Solid-shaped differences:

• useTheme() returns an accessor: read theme().highContrast, not theme.highContrast. The same applies to props.theme() in interpolations and in .attrs().
• class instead of className, including inside .attrs({ ... }).
• No jsx-runtime export. Solid compiles JSX natively, which means the css prop types activate simply by importing @yak/solid.
• Components run once. There is no re-render to recompute styles and Solid's reactivity handles it.

How it works

Like next-yak, the yak SWC compiler extracts your CSS at build time. At runtime only a tiny layer remains that merges class names and feeds dynamic values through CSS custom properties:

• Static styles become plain CSS classes. A static styled.div never subscribes to the theme and adds a single reactive class binding.
• Dynamic interpolations (${(props) => ...}) become CSS variables set on the element's inline style. Updates flow through one memo per component: the element is never re-created, only its class/style bindings change, and only props actually used by the CSS re-run the memo.

Requirements

• solid-js >= 2.0.0-rc.6 and @solidjs/web >= 2.0.0-rc.6
• @solidjs/vite-plugin >= 3.0.0-next (the Solid 2 line, npm tag next)
• yak-swc with yak-package auto-detection (bundled as a dependency, version released together with this package or newer)

See the examples/vite-solid app for a full setup.