Breakpoints not working?

[haikbvn]

Hi everyone!

I'm using TailwindCSS, Gulp and PostCSS but Breakpoints not working?

// tailwind.config.js file
module.exports = {
	purge: [],
	darkMode: 'media', // or 'media' or 'class'
	theme: {
		extend: {}
	},
	variants: {
		extend: {}
	},
	plugins: [
		require( '@tailwindcss/typography' ),
		require( '@tailwindcss/forms' )
	]
};

// postcss.config.js file
module.exports = {
	plugins: [
		require( 'tailwindcss' )
	]
};

// html
...
<div class="container flex justify-between items-center px-4 md:mx-auto">
...

Thanks!