Tailwind CSS Unknown at Rule

VSCode warning for Tailwind Directives

I was running into an issue with VSCode warnings on CSS "Unknown at rule" for Tailwind directives.

./styles/globals.css
@tailwind base;
^^^^^^^^^ 
Unknown at rule @tailwind css(unknownAtRules)
./styles/globals.css
@layer base {
  * {
    @apply text-gray-dark;
    ^^^^^^^^ 
    Unknown at rule @apply css(unknownAtRules)  }
}

VSCode Solution: Define Custom Data for CSS

The solution was to load a custom CSS dataset for Tailwind directives in a workspace settings file settings.json.

A list of the different Tailwind Directives in the docs: Functions & Directives

Note: It's usually necessary to reload the VS Code window for the change to be recognized.

.vscode/settings.json
{
  "css.customData": [".vscode/tailwindcss.json"],
}
.vscode/tailwindcss.json
{
  "version": 1.1,
  "atDirectives": [
    {
      "name": "@tailwind",
      "description": "Use the `@tailwind` directive to insert Tailwind's `base`, `components`, `utilities` and `screens` styles into your CSS.",
      "references": [
        {
          "name": "Tailwind Documentation",
          "url": "https://tailwindcss.com/docs/functions-and-directives#tailwind"
        }
      ]
    },
    {
      "name": "@apply",
      "description": "Use the `@apply` directive to inline any existing utility classes into your own custom CSS. This is useful when you find a common utility pattern in your HTML that you’d like to extract to a new component.",
      "references": [
        {
          "name": "Tailwind Documentation",
          "url": "https://tailwindcss.com/docs/functions-and-directives#apply"
        }
      ]
    },
    {
      "name": "@responsive",
      "description": "You can generate responsive variants of your own classes by wrapping their definitions in the `@responsive` directive:\n```css\n@responsive {\n  .alert {\n    background-color: #E53E3E;\n  }\n}\n```\n",
      "references": [
        {
          "name": "Tailwind Documentation",
          "url": "https://tailwindcss.com/docs/functions-and-directives#responsive"
        }
      ]
    },
    {
      "name": "@screen",
      "description": "The `@screen` directive allows you to create media queries that reference your breakpoints by **name** instead of duplicating their values in your own CSS:\n```css\n@screen sm {\n  /* ... */\n}\n```\n…gets transformed into this:\n```css\n@media (min-width: 640px) {\n  /* ... */\n}\n```\n",
      "references": [
        {
          "name": "Tailwind Documentation",
          "url": "https://tailwindcss.com/docs/functions-and-directives#screen"
        }
      ]
    },
    {
      "name": "@variants",
      "description": "Generate `hover`, `focus`, `active` and other **variants** of your own utilities by wrapping their definitions in the `@variants` directive:\n```css\n@variants hover, focus {\n   .btn-brand {\n    background-color: #3182CE;\n  }\n}\n```\n",
      "references": [
        {
          "name": "Tailwind Documentation",
          "url": "https://tailwindcss.com/docs/functions-and-directives#variants"
        }
      ]
    }
  ]
}