Theming

You can choose between using CSS variables or Tailwind CSS utility classes for theming.

Utility classes

<div className="bg-zinc-950 dark:bg-white" />

To use utility classes for theming set tailwind.cssVariables to false in your components.json file.

components.json

{
  "style": "default",
  "rsc": true,
  "tailwind": {
    "config": "tailwind.config.ts",
    "css": "app/globals.css",
    "baseColor": "slate",
    "cssVariables": false
  },
  "aliases": {
    "components": "@/components",
    "utils": "@/lib/utils"
  }
}

CSS Variables

<div className="bg-background text-foreground" />

To use CSS variables for theming set tailwind.cssVariables to true in your components.json file.

components.json

{
  "style": "default",
  "rsc": true,
  "tailwind": {
    "config": "tailwind.config.ts",
    "css": "app/globals.css",
    "baseColor": "zinc",
    "cssVariables": true
  },
  "aliases": {
    "components": "@/components",
    "utils": "@/lib/utils"
  }
}

We use a simple background and foreground convention for colors. The background variable is used for the background color of the component and the foreground variable is used for the text color.

The background suffix is omitted when the variable is used for the background color of the component.

Given the following CSS variables:

--primary: 222.2 47.4% 11.2%;
--primary-foreground: 210 40% 98%;

The background color of the following component will be hsl(var(--primary)) and the foreground color will be hsl(var(--primary-foreground)).

<div className="bg-primary text-primary-foreground">Hello</div>

CSS variables must be defined without color space function. See the Tailwind CSS documentation

Here's my globals.css variables

globals.css

@tailwind base;
@tailwind components;
@tailwind utilities;
 
@layer base {
  :root {
    --background: 0 0% 100%;
    --foreground: 240 10% 3.9%;
 
    --card: 0 0% 100%;
    --card-foreground: 240 10% 3.9%;
 
    --popover: 0 0% 100%;
    --popover-foreground: 240 10% 3.9%;
 
    --primary: 240 5.9% 10%;
    --primary-foreground: 0 0% 98%;
 
    --secondary: 240 4.8% 95.9%;
    --secondary-foreground: 240 5.9% 10%;
 
    --muted: 240 4.8% 95.9%;
    --muted-foreground: 240 3.8% 46.1%;
 
    --accent: 240 4.8% 95.9%;
    --accent-foreground: 240 5.9% 10%;
 
    --destructive: 0 84.2% 60.2%;
    --destructive-foreground: 0 0% 98%;
 
    --border: 240 5.9% 90%;
    --input: 240 5.9% 90%;
    --ring: 240 10% 3.9%;
 
    --radius: 0.5rem;
  }
 
  .dark {
    --background: 240 10% 3.9%;
    --foreground: 0 0% 98%;
 
    --card: 240 10% 3.9%;
    --card-foreground: 0 0% 98%;
 
    --popover: 240 10% 3.9%;
    --popover-foreground: 0 0% 98%;
 
    --primary: 0 0% 98%;
    --primary-foreground: 240 5.9% 10%;
 
    --secondary: 240 3.7% 15.9%;
    --secondary-foreground: 0 0% 98%;
 
    --muted: 240 3.7% 15.9%;
    --muted-foreground: 240 5% 64.9%;
 
    --accent: 240 3.7% 15.9%;
    --accent-foreground: 0 0% 98%;
 
    --destructive: 0 62.8% 30.6%;
    --destructive-foreground: 0 0% 98%;
 
    --border: 240 3.7% 15.9%;
    --input: 240 3.7% 15.9%;
    --ring: 240 4.9% 83.9%;
  }
}
 
@layer base {
  * {
    @apply border-border;
  }
  html {
    @apply scroll-smooth;
  }
 
  body {
    @apply bg-background text-foreground font-sans;
  }
}

Adding new colors

To add new colors, you need to add them to your CSS file and to your tailwind.config.ts file.

app/globals.css

:root {
  --warning: 38 92% 50%;
  --warning-foreground: 48 96% 89%;
}
 
.dark {
  --warning: 48 96% 89%;
  --warning-foreground: 38 92% 50%;
}

tailwind.config.ts

module.exports = {
  theme: {
    extend: {
      colors: {
        warning: 'hsl(var(--warning))',
        'warning-foreground': 'hsl(var(--warning-foreground))',
      },
    },
  },
}

You can now use the warning utility class in your components.

<div className="bg-warning text-warning-foreground" />

Other color formats

For effective theming, I recommend leveraging HSL colors (Hue, Saturation, Lightness). HSL offers intuitive control over color properties, making it ideal for creating cohesive color schemes. However, if you prefer, other color formats can also be utilized. To explore a wide range of theme options specifically tailored for shadcn/ui, the resource at ui.jln.dev provides over 10,000 variations, offering ample inspiration and customization possibilities

See the Tailwind CSS documentation for more information on using rgb, rgba or hsl colors.

Theming

Utility classes

CSS Variables

Convention

Adding new colors

Other color formats

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