<div class="percentage">
  My Keyframe is defined with percentages(%)
  <p>
    0% => 25% => 50% => 100%
  </p>
</div>

body {
  background: #000000;
  display: flex;
  justify-content: center;
  flex-direction: column;
  align-items: center;
  padding:10px;
  font-family: 'Roboto Mono', monospace;
}

div.percentage {
  width: 80%;
  height: 400px;
  background-color: orange;
  padding: 10px;
  border-radius: 4px;
  text-align: center;
  animation-name: percentage;
  animation-duration: 5s;
}

@keyframes percentage {
  0% {background-color: orange;}
  25% {background-color: green; color: white;}
  50% {background-color: white; color: black;}
  100% {background-color: red; color: white;}
}