.countdown-10s {
}

.countdown-1s::after,
.countdown-10s::after {
  width: 100vw;
  position: relative;
  display: block;
  clear: both;
  color: orange;
  font-size: 300%;
  text-align: center;
}

.countdown-1s::after {
  content: '1';
}
.countdown-10s::after {
  animation: countingdown10 linear 10s;
  -webkit-animation: countingdown10 linear 10s;
  content: '_';
}

@keyframes countingdown10 {
  0% {content: '9';}
  10% {content: '8';}
  20% {content: '7';}
  30% {content: '6';}
  40% {content: '5';}
  50% {content: '4';}
  70% {content: '3';}
  80% {content: '2';}
  90% {content: '1';}
  100% {content: '0';}
}
@-webkit-keyframes countingdown10 {
  0% {content: '9';}
  10% {content: '8';}
  20% {content: '7';}
  30% {content: '6';}
  40% {content: '5';}
  50% {content: '4';}
  70% {content: '3';}
  80% {content: '2';}
  90% {content: '1';}
  100% {content: '0';}
}