.centernayef {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
  }

#myVideonayef {
  position: fixed;
  right: 0;
  bottom: 0;
  min-width: 100%; 
  min-height: 100%;
}


@media only screen and (max-width: 600px) {
  .videocenter {
    width: 100%;
    height: 470px;
    position: relative;
    left:50%;
    top:30%;
    transform:translate3d(-50%,-50%,0);
    overflow:hidden;
    box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
  }
}

      .videocenter {
        width: 100%;
        height: 470px;
        position: relative;
        left:50%;
        top:30%;
        transform:translate3d(-50%,-50%,0);
        overflow:hidden;
        box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
  }


  .leftnayef {
    left: 100px;;
  }

  .centernayef {
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 50%;
}