Demo per The Guard
<style>#SCcont8689{width: 100%;padding-top: 56.25%;position: relative;}#SCgFrame8689 {position: absolute;top: 0;left: 0;bottom: 0;right: 0;}</style> <div id="SCcont8689"> <iframe id="SCgFrame8689" frameborder="0" allowfullscreen="" mozallowfullscreen="" webkitallowfullscreen="" hspace="0" vspace="0" scrolling="none" src="https://slotcatalog.com/it/slots/The-Guard?ajax=1&blck=demo-widget" width="100%" height="100%"></iframe> </div>
copia