index.js

import './style';
import { Component } from 'preact';

export default class App extends Component {
	render() {
		return (
			<div>
				<h1>Hello, World!</h1>
			</div>
		);
	}
}

package.json

{
  "name": "preact-cli-starter",
  "version": "1.0.0",
  "scripts": {
    "start": "preact watch",
    "build": "preact build",
    "serve": "serve build -s -n"
  },
  "dependencies": {
    "preact": "^10.0.5",
    "preact-render-to-string": "^5.1.1"
  },
  "devDependencies": {
    "eslint": "6.7.2",
    "eslint-config-developit": "^1.1.1",
    "preact-cli": "^3.0.0-rc.6",
    "serve": "^11.2.0"
  },
  "eslintConfig": {
    "extends": "developit"
  }
}

style.css

html, body {
	font: 14px/1.21 'Helvetica Neue', arial, sans-serif;
	font-weight: 400;
}

h1 {
	text-align: center;
}