<!DOCTYPE html>
<html>
<head>
<script>
function boom()
{
var ctx = document.querySelector("canvas").getContext('2d');
ctx.rotate(470);
ctx.clearRect(71.5, -0.5, 666, 380);
}
</script>
</head>
<body onload="boom();"><canvas width="41700" height="500"></canvas></body>
</html>