Dart Pad with html index.html

index.html

<h1 id="header">empty</h1>

main.dart

/// https://dart.dev/tutorials/web/low-level-html/connect-dart-html

import 'dart:html';

void main() {
  final header = querySelector('#header');
  header?.text = "Hello, World!";
}

styles.css

body {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  position: absolute;
  width: 100%;
  height: 100%;
}

h1 {
  color: white;
  font-family: Arial, Helvetica, sans-serif;
}