html {
  background-color: #000000; 
}

.embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 90%; height: auto; margin: 0 auto;} 
.embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }