browser.html

<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title></title>
	<link rel="stylesheet" href="ui.css">
</head>

<body>
	<style>
		body{
			position: fixed;
			padding: 0;
			margin: 0;
		}
		#flex {
			display: flex;
			flex-direction: column;
			height: 100vh;
		}
		iframe {
			width: 100vw;
			flex: 0 1 100vh;
		}
	</style>
	<div id=flex>
		<input type="text" style="font-family: monospace;" name="" id="url" value="">
		<iframe id="i" frameborder="0" style="background-color: #fff;"></iframe>
	</div>
	<script>
		setTimeout(() => {
			if ((window.arg || '').startsWith("$open ")) {
				i.src = url.value = window.arg.slice(6)
			}
			url.onkeypress = (ev) => {
				if((ev.code||ev.key)!="Enter")return;
				i.src=url.value
			}
		}, 100)
	</script>
</body>

</html>