<script>
const trigger = document.querySelector('#demo-modal-open');
const dialog = document.querySelector('#demo-modal');
trigger.addEventListener('click', () => {
dialog.showModal();
});
</script>
<button id="demo-modal-open">Open</button>
<dialog id="demo-modal">
<p>Login</p>
<form method="dialog">
<input type="text" placeholder="username" />
<input type="password" placeholder="password" />
<button type="submit">Login</button>
</form>
</dialog>