Tailwind CSS classes is not working with React, error "You need to enable JavaScript to run this app..."

Talwind CSS is not working with React. I have installed Tailwind CSS as per the documentation (https://v1.tailwindcss.com/docs/installation) and my code is below.

Can someone help me?

Here is my browser pic of the inspect to understand my problem

Here is my package.json file

{
  "name": "my-app",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^5.16.2",
    "@testing-library/react": "^12.1.2",
    "@testing-library/user-event": "^13.5.0",
    "autoprefixer": "^10.4.2",
    "postcss-cli": "^9.1.0",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-scripts": "5.0.0",
    "tailwindcss": "^3.0.18",
    "web-vitals": "^2.1.4"
  },
  "scripts": {
    "build:css": "postcss src/assets/css/tailwind.css -o src/assets/css/style.css",
    "start": "npm run build:css && react-scripts start ",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}

Below is my postcss.config.js

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

Below is my tailwind.config.js

  module.exports = {
  content: [
    "./src/**/*.{js,jsx,ts,tsx}",
  ],
  plugins: [
    // ...
    require('tailwindcss'),
    require('autoprefixer'),
    // ...
  ]
}

Later, I edited my index.js

import React from "react";
import ReactDOM from "react-dom";
import App from "./App";

//const App = require("./App");

ReactDOM.render(
    <App title="Heyy React Dev Tool"/>, document.getElementById("root")
);

I also edited my App.js like below

  import React from "react";
  import "./assets/css/style.css"

    function App({title}) {
      return (
          <div>
            <div className="bg-gray-600 text-white p-5 border">{title}</div>        
          </div>
      );
    
    }  
    export default App;

Last but now least these is my style.css file is generated

Style.css

/*
! tailwindcss v3.0.18 | MIT License | https://tailwindcss.com
*//*
1. Prevent padding and border from affecting element width. (https://github.com/mozdevs/cssremedy/issues/4)
2. Allow adding a border to an element by just adding a border-width. (https://github.com/tailwindcss/tailwindcss/pull/116)
*/

*,
::before,
::after {
  box-sizing: border-box; /* 1 */
  border-width: 0; /* 2 */
  border-style: solid; /* 2 */
  border-color: #e5e7eb; /* 2 */
}

::before,
::after {
  --tw-content: '';
}

/*
1. Use a consistent sensible line-height in all browsers.
2. Prevent adjustments of font size after orientation changes in iOS.
3. Use a more readable tab size.
4. Use the user's configured `sans` font-family by default.
*/

html {
  line-height: 1.5; /* 1 */
  -webkit-text-size-adjust: 100%; /* 2 */ /* 3 */
  tab-size: 4; /* 3 */
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji"; /* 4 */
}

/*
1. Remove the margin in all browsers.
2. Inherit line-height from `html` so users can set them as a class directly on the `html` element.
*/

body {
  margin: 0; /* 1 */
  line-height: inherit; /* 2 */
}

/*
1. Add the correct height in Firefox.
2. Correct the inheritance of border color in Firefox. (https://bugzilla.mozilla.org/show_bug.cgi?id=190655)
3. Ensure horizontal rules are visible by default.
*/

hr {
  height: 0; /* 1 */
  color: inherit; /* 2 */
  border-top-width: 1px; /* 3 */
}

/*
Add the correct text decoration in Chrome, Edge, and Safari.
*/

abbr:where([title]) {
  text-decoration: underline dotted;
}

/*
Remove the default font size and weight for headings.
*/

h1,
h2,
h3,
h4,
h5,
h6 {
  font-size: inherit;
  font-weight: inherit;
}

/*
Reset links to optimize for opt-in styling instead of opt-out.
*/

a {
  color: inherit;
  text-decoration: inherit;
}

/*
Add the correct font weight in Edge and Safari.
*/

b,
strong {
  font-weight: bolder;
}

/*
1. Use the user's configured `mono` font family by default.
2. Correct the odd `em` font sizing in all browsers.
*/

code,
kbd,
samp,
pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; /* 1 */
  font-size: 1em; /* 2 */
}

/*
Add the correct font size in all browsers.
*/

small {
  font-size: 80%;
}

/*
Prevent `sub` and `sup` elements from affecting the line height in all browsers.
*/

sub,
sup {
  font-size: 75%;
  line-height: 0;
  position: relative;
  vertical-align: baseline;
}

sub {
  bottom: -0.25em;
}

sup {
  top: -0.5em;
}

/*
1. Remove text indentation from table contents in Chrome and Safari. (https://bugs.chromium.org/p/chromium/issues/detail?id=999088, https://bugs.webkit.org/show_bug.cgi?id=201297)
2. Correct table border color inheritance in all Chrome and Safari. (https://bugs.chromium.org/p/chromium/issues/detail?id=935729, https://bugs.webkit.org/show_bug.cgi?id=195016)
3. Remove gaps between table borders by default.
*/

table {
  text-indent: 0; /* 1 */
  border-color: inherit; /* 2 */
  border-collapse: collapse; /* 3 */
}

/*
1. Change the font styles in all browsers.
2. Remove the margin in Firefox and Safari.
3. Remove default padding in all browsers.
*/

button,
input,
optgroup,
select,
textarea {
  font-family: inherit; /* 1 */
  font-size: 100%; /* 1 */
  line-height: inherit; /* 1 */
  color: inherit; /* 1 */
  margin: 0; /* 2 */
  padding: 0; /* 3 */
}

/*
Remove the inheritance of text transform in Edge and Firefox.
*/

button,
select {
  text-transform: none;
}

/*
1. Correct the inability to style clickable types in iOS and Safari.
2. Remove default button styles.
*/

button,
[type='button'],
[type='reset'],
[type='submit'] {
  -webkit-appearance: button; /* 1 */
  background-color: transparent; /* 2 */
  background-image: none; /* 2 */
}

/*
Use the modern Firefox focus style for all focusable elements.
*/

:-moz-focusring {
  outline: auto;
}

/*
Remove the additional `:invalid` styles in Firefox. (https://github.com/mozilla/gecko-dev/blob/2f9eacd9d3d995c937b4251a5557d95d494c9be1/layout/style/res/forms.css#L728-L737)
*/

:-moz-ui-invalid {
  box-shadow: none;
}

/*
Add the correct vertical alignment in Chrome and Firefox.
*/

progress {
  vertical-align: baseline;
}

/*
Correct the cursor style of increment and decrement buttons in Safari.
*/

::-webkit-inner-spin-button,
::-webkit-outer-spin-button {
  height: auto;
}

/*
1. Correct the odd appearance in Chrome and Safari.
2. Correct the outline style in Safari.
*/

[type='search'] {
  -webkit-appearance: textfield; /* 1 */
  outline-offset: -2px; /* 2 */
}

/*
Remove the inner padding in Chrome and Safari on macOS.
*/

::-webkit-search-decoration {
  -webkit-appearance: none;
}

/*
1. Correct the inability to style clickable types in iOS and Safari.
2. Change font properties to `inherit` in Safari.
*/

::-webkit-file-upload-button {
  -webkit-appearance: button; /* 1 */
  font: inherit; /* 2 */
}

/*
Add the correct display in Chrome and Safari.
*/

summary {
  display: list-item;
}

/*
Removes the default spacing and border for appropriate elements.
*/

blockquote,
dl,
dd,
h1,
h2,
h3,
h4,
h5,
h6,
hr,
figure,
p,
pre {
  margin: 0;
}

fieldset {
  margin: 0;
  padding: 0;
}

legend {
  padding: 0;
}

ol,
ul,
menu {
  list-style: none;
  margin: 0;
  padding: 0;
}

/*
Prevent resizing textareas horizontally by default.
*/

textarea {
  resize: vertical;
}

/*
1. Reset the default placeholder opacity in Firefox. (https://github.com/tailwindlabs/tailwindcss/issues/3300)
2. Set the default placeholder color to the user's configured gray 400 color.
*/

input::placeholder,
textarea::placeholder {
  opacity: 1; /* 1 */
  color: #9ca3af; /* 2 */
}

/*
Set the default cursor for buttons.
*/

button,
[role="button"] {
  cursor: pointer;
}

/*
Make sure disabled buttons don't get the pointer cursor.
*/
:disabled {
  cursor: default;
}

/*
1. Make replaced elements `display: block` by default. (https://github.com/mozdevs/cssremedy/issues/14)
2. Add `vertical-align: middle` to align replaced elements more sensibly by default. (https://github.com/jensimmons/cssremedy/issues/14#issuecomment-634934210)
   This can trigger a poorly considered lint error in some tools but is included by design.
*/

img,
svg,
video,
canvas,
audio,
iframe,
embed,
object {
  display: block; /* 1 */
  vertical-align: middle; /* 2 */
}

/*
Constrain images and videos to the parent width and preserve their intrinsic aspect ratio. (https://github.com/mozdevs/cssremedy/issues/14)
*/

img,
video {
  max-width: 100%;
  height: auto;
}

/*
Ensure the default browser behavior of the `hidden` attribute.
*/

[hidden] {
  display: none;
}

*, ::before, ::after {
  --tw-translate-x: 0;
  --tw-translate-y: 0;
  --tw-rotate: 0;
  --tw-skew-x: 0;
  --tw-skew-y: 0;
  --tw-scale-x: 1;
  --tw-scale-y: 1;
  --tw-pan-x:  ;
  --tw-pan-y:  ;
  --tw-pinch-zoom:  ;
  --tw-scroll-snap-strictness: proximity;
  --tw-ordinal:  ;
  --tw-slashed-zero:  ;
  --tw-numeric-figure:  ;
  --tw-numeric-spacing:  ;
  --tw-numeric-fraction:  ;
  --tw-ring-inset:  ;
  --tw-ring-offset-width: 0px;
  --tw-ring-offset-color: #fff;
  --tw-ring-color: rgb(59 130 246 / 0.5);
  --tw-ring-offset-shadow: 0 0 #0000;
  --tw-ring-shadow: 0 0 #0000;
  --tw-shadow: 0 0 #0000;
  --tw-shadow-colored: 0 0 #0000;
  --tw-blur:  ;
  --tw-brightness:  ;
  --tw-contrast:  ;
  --tw-grayscale:  ;
  --tw-hue-rotate:  ;
  --tw-invert:  ;
  --tw-saturate:  ;
  --tw-sepia:  ;
  --tw-drop-shadow:  ;
  --tw-backdrop-blur:  ;
  --tw-backdrop-brightness:  ;
  --tw-backdrop-contrast:  ;
  --tw-backdrop-grayscale:  ;
  --tw-backdrop-hue-rotate:  ;
  --tw-backdrop-invert:  ;
  --tw-backdrop-opacity:  ;
  --tw-backdrop-saturate:  ;
  --tw-backdrop-sepia:  ;
} 

'```

Solution

I've looked at your repo: and even though you said you followed the guide, you didn't. The issue boils down to not really following through the documentation properly.

This line is missing in your tailwind.config.js file, which causes tailwind to fail to detect class usage in all your .js file:

module.exports = {
  // You are missing this block that defines what files tailwind should scan for usage
  content: [
    "./src/**/*.{js,jsx,ts,tsx}",
  ],
  theme: {
    extend: {},
  },
  plugins: [],
}

Once you add this line your CSS should build properly:

Other signs that you didn't follow the guide properly:

tailwindcss is listed as a dependency and not a devDependency
Your tailwind.config.js file appears outdated. Are you sure you ran npx tailwindcss init properly? Are you sure that you are indeed running v3 of Tailwind CSS?