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<html>
<body>
<h1>Allow Attribute Example for Iframe with Optimization Best Practices</h1>
<iframe
width="500px"
height="300px"
src="https://www.thewebmaster.com"
allow="layout-animations 'none'; unoptimized-images 'none'; oversized-images 'none'; sync-script 'none'; sync-xhr 'none'; unsized-media 'none';"
></iframe>
</body>
</html>