214 lines
6.2 KiB
Markdown
214 lines
6.2 KiB
Markdown
# Customization & Theming
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Components reference semantic CSS variable tokens. Change the variables to change every component.
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## Contents
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- How it works (CSS variables → Tailwind utilities → components)
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- Color variables and OKLCH format
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- Dark mode setup
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- Changing the theme (presets, CSS variables)
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- Adding custom colors (Tailwind v3 and v4)
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- Border radius
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- Customizing components (variants, class, wrappers)
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- Checking for updates
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---
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## How It Works
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1. CSS variables defined in `:root` (light) and `.dark` (dark mode).
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2. Tailwind maps them to utilities: `bg-primary`, `text-muted-foreground`, etc.
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3. Components use these utilities — changing a variable changes all components that reference it.
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---
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## Color Variables
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Every color follows the `name` / `name-foreground` convention. The base variable is for backgrounds, `-foreground` is for text/icons on that background.
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| Variable | Purpose |
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| -------------------------------------------- | -------------------------------- |
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| `--background` / `--foreground` | Page background and default text |
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| `--card` / `--card-foreground` | Card surfaces |
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| `--primary` / `--primary-foreground` | Primary buttons and actions |
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| `--secondary` / `--secondary-foreground` | Secondary actions |
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| `--muted` / `--muted-foreground` | Muted/disabled states |
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| `--accent` / `--accent-foreground` | Hover and accent states |
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| `--destructive` / `--destructive-foreground` | Error and destructive actions |
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| `--border` | Default border color |
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| `--input` | Form input borders |
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| `--ring` | Focus ring color |
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| `--chart-1` through `--chart-5` | Chart/data visualization |
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| `--sidebar-*` | Sidebar-specific colors |
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| `--surface` / `--surface-foreground` | Secondary surface |
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Colors use OKLCH: `--primary: oklch(0.205 0 0)` where values are lightness (0–1), chroma (0 = gray), and hue (0–360).
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---
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## Dark Mode
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Class-based toggle via `.dark` on the root element. In SvelteKit, use [mode-watcher](https://github.com/svecosystem/mode-watcher) (see [Dark mode — Svelte](https://shadcn-svelte.com/docs/dark-mode/svelte)):
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```svelte
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<script lang="ts">
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import { ModeWatcher } from "mode-watcher";
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let { children } = $props();
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</script>
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<ModeWatcher />
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{@render children?.()}
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```
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---
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## Changing the Theme
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Use a **preset** from the design-system builder on [shadcn-svelte.com](https://shadcn-svelte.com) and pass it to `init`:
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```bash
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npx shadcn-svelte@latest init --preset <code>
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```
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Or edit CSS variables directly in the file set in `components.json` as `tailwind.css` (for example `src/app.css`).
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To align config and components with a new preset, re-run `init` with `--preset` and confirm overwrites when prompted.
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---
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## Adding Custom Colors
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Add variables to the global CSS file path in `components.json` (`tailwind.css`). Do not create a second global CSS file for theming unless the project already uses that pattern.
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```css
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/* 1. Define in the global CSS file. */
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:root {
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--warning: oklch(0.84 0.16 84);
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--warning-foreground: oklch(0.28 0.07 46);
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}
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.dark {
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--warning: oklch(0.41 0.11 46);
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--warning-foreground: oklch(0.99 0.02 95);
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}
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```
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```css
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/* 2a. Register with Tailwind v4 (@theme inline). */
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@theme inline {
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--color-warning: var(--warning);
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--color-warning-foreground: var(--warning-foreground);
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}
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```
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On Tailwind v3, register in `tailwind.config.js` (see the [Tailwind v3 docs](https://tw3.shadcn-svelte.com) if you maintain a legacy setup):
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```js
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// 2b. Register with Tailwind v3 (tailwind.config.js).
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module.exports = {
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theme: {
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extend: {
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colors: {
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warning: "oklch(var(--warning) / <alpha-value>)",
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"warning-foreground":
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"oklch(var(--warning-foreground) / <alpha-value>)",
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},
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},
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},
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};
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```
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```svelte
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<!-- 3. Use in components. -->
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<div class="bg-warning text-warning-foreground">Warning</div>
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```
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---
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## Border Radius
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`--radius` controls border radius globally. Components derive values from it (`rounded-lg` = `var(--radius)`, `rounded-md` = `calc(var(--radius) - 2px)`).
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---
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## Customizing Components
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See also: [rules/styling.md](./rules/styling.md) for Incorrect/Correct examples.
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Prefer these approaches in order:
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### 1. Built-in variants
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```svelte
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<script lang="ts">
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import { Button } from "$lib/components/ui/button";
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</script>
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<Button variant="outline" size="sm">Click</Button>
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```
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### 2. Tailwind classes via `class`
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```svelte
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<script lang="ts">
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import * as Card from "$lib/components/ui/card";
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</script>
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<Card.Root class="mx-auto max-w-md">
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<Card.Content>...</Card.Content>
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</Card.Root>
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```
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### 3. Add a new variant
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Edit the component source to add a variant via `tailwind-variants` / `cva` in the `.svelte` or shared variants file:
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```ts
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// e.g. in button variants
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warning: "bg-warning text-warning-foreground hover:bg-warning/90",
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```
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### 4. Wrapper components
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Compose shadcn-svelte primitives into higher-level `.svelte` files:
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```svelte
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<script lang="ts">
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import * as AlertDialog from "$lib/components/ui/alert-dialog";
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let { title, description, onConfirm, children } = $props();
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let open = $state(false);
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</script>
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<AlertDialog.Root bind:open>
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<AlertDialog.Trigger>
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{@render children?.()}
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</AlertDialog.Trigger>
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<AlertDialog.Content>
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<AlertDialog.Header>
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<AlertDialog.Title>{title}</AlertDialog.Title>
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<AlertDialog.Description>{description}</AlertDialog.Description>
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</AlertDialog.Header>
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<AlertDialog.Footer>
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<AlertDialog.Cancel>Cancel</AlertDialog.Cancel>
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<AlertDialog.Action
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onclick={() => {
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onConfirm?.();
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open = false;
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}}>Confirm</AlertDialog.Action
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>
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</AlertDialog.Footer>
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</AlertDialog.Content>
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</AlertDialog.Root>
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```
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---
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## Checking for Updates
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```bash
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npx shadcn-svelte@latest update button
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npx shadcn-svelte@latest update --all
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```
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See [Updating Components in SKILL.md](./SKILL.md#updating-components). Review `git diff` after `update` to see what changed.
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