<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>bora is bitch</title>
<style>
body,
html {
width: 100%;
height: 100%;
margin: 0px;
padding: 0px;
}
#gameCanvas {
width: auto;
height: 100%;
background-color: blueviolet;
}
</style>
</head>
<body>
<center style="height: 100%">
<div id="gameCanvas">
burası oyun
</div>
</center>
</body>
<script>
var height = screen.availHeight;
var width = 0;
width = height * 9 / 16;
var widthScreen = screen.width;
var marginForGameCanvas = (widthScreen - width) / 2;
document.getElementById("gameCanvas").style.width = width + "px";
</script>
</html>