Text color not changing using NextJS with Tailwind CSS

In my NextJS app I'm using an <h1> tag for the text and wrap it in a <div> but when I try to apply a color to the text, it doesn't work. I even added in my global.css but it throws an error.

    <div className="mt-2 flex justify-start items-center text-2xl font-bold text-gray-300">
        <Image 
            src={Logo}
            width={40}
            height={40}
        />
        <h1>some text here</h1>
    </div>

The code above does not throw an error, but it also doesn't apply the style to the text.

styles/global.css

    @tailwind base;
    @tailwind components;
    @tailwind utilities;
    
    @layer base{
        body{
            @apply bg-[#06202A] text-gray-300; 
        }
    }

Applying styles in the base layer (above) throws the following error.

.../styles/globals.css The text-gray-300 class does not exist. If text-gray-300 is a custom class, make sure it is defined within a @layer directive.

tailwind.config.js

@type {import('tailwindcss').Config} */
    module.exports = {
      mode: "jit",
      content: [
        "./pages/**/*.{js,ts,jsx,tsx}",
        "./components/**/*.{js,ts,jsx,tsx}",
      ],
      theme: {
        colors: {
          'main-bg-color': '#02172F',
          'text-gray-color': '#fff'
        },
        extend: {},
      },
      plugins: [],
    }

postcss.config.js

    module.exports = {
      plugins: {
        tailwindcss: {},
        autoprefixer: {},
      },
    }

Why is this not working?

Solution

You are replacing the default colors with your new additions. To add colors, but keep the defaults, you should place your new colors within the extend property.

module.exports = {
  mode: "jit",
  content: [
    "./pages/**/*.{js,ts,jsx,tsx}",
    "./components/**/*.{js,ts,jsx,tsx}",
  ],
  theme: {
    extend: {
      colors: {
        'main-bg-color': '#02172F',
        'text-gray-color': '#fff'
      },
    },
  },
  plugins: [],
}

Also, the mode setting is no longer needed in Tailwind 3.0+. If you're still using V2, I would recommend upgrading if possible. If you cannot upgrade for some reason, I would like to point out that the default color classes are different between Tailwind 2 and 3, and you will have to reference the correct version's docs for the proper color set.