multiple background image

Hello!
Can you explain please why my second background image doesn’t show up?
this is my CSS:

 html{
    background-image: url("https://s3-us-west- 
    2.amazonaws.com/s.cdpn.io/104215/launch-day- 
    boom_copy.svg"), url("https://s3-us-west- 
   2.amazonaws.com/s.cdpn.io/104215/superhero-152840.png");
    background-repeat: no-repeat, no-repeat;
    background-size: cover, 20%;
    background-position: center center ,left top;
    height: 100%;
 }

Your other image is covering it