/share/WebKit/editing/contenteditable.html

<!DOCTYPE html>
<html>
	<head>
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<style>
html {
	height: calc(100% - env(safe-area-inset-top) - env(safe-area-inset-bottom));
}

body {
	min-height: 100%;
	margin: 0;
	padding: 0.5em;
	font-family: ui-monospace;
}
		</style>
	</head>
	<body contenteditable>hello world</body>
</html>