Quizapp-Vite-Reduxttk-TailwindCSS

I think it's because in the build step, Vite will try to find the image after Tailwind has created the CSS rule inside index.css, so you want the url() inside tailwind.config.js to be relative to index.css. It might also work to use an absolute path from the project root.

// tailwind.config.js
export default {
  theme: {
    extend: {
      backgroundImage: {
        "pattern-dark": "url('./assets/images/bg-mobile.svg')",
        "pattern-light": "url('./assets/images/bg-mobile-light.svg')",
        "pattern-dark-tablet": "url('./assets/images/bg-tablet.svg')",
        "pattern-light-tablet": "url('./assets/images/bg-tablet-light.png')",
        // or
        "pattern-dark": "url('/src/assets/images/bg-mobile.svg')",
        "pattern-light": "url('/src/assets/images/bg-mobile-light.svg')",
        "pattern-dark-tablet": "url('/src/assets/images/bg-tablet.svg')",
        "pattern-light-tablet": "url('/src/assets/images/bg-tablet-light.png')",
      },
    },
  },
};