html,
body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
 }

body {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #f8f9fa; 
} 

iframe {
    width: 100%; 
    height: 100%; 
    border: none; 
    max-width: 100vw; 
    max-height: 100vh; 
}