body {
  background-color: rgb(6, 6, 6);
}

.battery {
  position: relative;
  margin: 20% auto 0;
  width: 300px;
  border: 10px solid #3459e6;
  height: 120px;
  border-radius: 15px;
}

.battery:before {
  content: '';
  position: absolute;
  top: 6px;
  left: 6px;
  height: 88px;
  background-color: #009dff;
  border-radius: 5px;
  animation: full 5s linear infinite;
}

.battery:after {
  content: '';
  position: absolute;
  right: -30px;
  top: 28px;
  width: 15px;
  height: 50px;
  background-color: #3459e6;
  border-bottom-right-radius: 90px;
  border-top-right-radius: 90px;
}

@keyframes full {
  0% {
    width: 0%;
  }
  25% {
    width: 24%;
  }
  50% {
    width: 48%;
  }
  75% {
    width: 72%;
  }
  100% {
    width: 96%;
  }
}