.embed { 
    position: relative; 
    padding-bottom: 56.25%; 
    height: 0; 
    overflow: hidden; 
    max-width: 100%;
} 

.embed iframe, .embed object, .embed embed { 
    position: absolute; 
    top: 0; 
    left: 0; 
    width: 100%; 
    height: 100%; 
}