test-tube.css

body {
  background-color: #1d1d19;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  padding: 0;
  margin: 0;
  font-family: sans-serif;
}

:root {
  --tube-percentage: 50%;
  --tube-title: "50%";
  --tube-color: #9198e5;
}

.tube {
  position: relative;
  height: 200px;
  width: 50px;
  border: 3px solid #272822;
  border-radius: 0 0 50rem 50rem;
  background-color: #272822;
}

.tube::after {
  content: "";
  position: absolute;
  left: -10px;
  top: -3px;
  width: calc(100% + 20px);
  height: 8px;
  border-radius: 50rem;
  background-color: #272822;
}

.tube .body {
  position: absolute;
  border-radius: inherit;
  height: 100%;
  width: 100%;
  bottom: 0;
  overflow: hidden;
  z-index: 5;
}

.tube .shine {
  position: absolute;
  left: 10%;
  top: 0;
  width: 10%;
  height: 100%;
  z-index: 90;
  opacity: 0.2;
}

.tube .shine::before,
.tube .shine::after {
  content: "";
  position: absolute;
  background-color: #fff;
  border-radius: 50rem;
  top: 10%;
  height: 40%;
  width: 100%;
}

.tube .shine::after {
  height: 15%;
  top: 60%;
  bottom: 0;
}

@keyframes liquid {
  0% {
    transform: translateX(-50%) rotate(0deg);
  }

  100% {
    transform: translateX(-50%) rotate(360deg);
  }
}

.tube .liquid {
  position: absolute;
  height: 80%;
  width: 100%;
  bottom: 0;
}

.tube .liquid .percentage {
  position: absolute;
  height: var(--tube-percentage);
  width: 100%;
  bottom: 0;
  left: 0;
  z-index: 80;
  transition: 1s;
}

.tube .liquid .percentage::after,
.tube .liquid .percentage::before {
  position: absolute;
  content: "";
  width: 200px;
  height: 200px;
  border-radius: 75px;
  animation: liquid 4s infinite linear;
  transform: translateX(-50%);
  left: 50%;
  top: 0;
  background: var(--tube-color);
  transition: 1s;
}

.tube .liquid .percentage::after {
  opacity: 0.4;
  animation-direction: reverse;
  border-radius: 60px;
}

@keyframes bubble {
  from {
    background: #272822;
    transform: scale(0.3) rotate(50deg);
    margin-left: 0;
  }

  10% {
    margin-left: 1px;
  }

  20% {
    margin-left: -1px;
  }

  30% {
    margin-left: 1px;
  }

  40% {
    margin-left: -1px;
  }

  50% {
    margin-left: 1px;
    background: var(--tube-color);
    transform: scale(0.85) rotate(50deg);
    opacity: .75;
  }

  60% {
    margin-left: -1px;
  }

  70% {
    margin-left: 1px;
  }

  80% {
    margin-left: -1px;
  }

  90% {
    margin-left: 1px;
  }

  to {
    margin-left: -1px;
    bottom: 135%;
    opacity: 0;
    transform: scale(1) rotate(50deg);
  }
}

.tube .bubbles {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: calc(var(--tube-percentage) + calc(100% - var(--tube-percentage)));
  z-index: 10;
}

.tube .bubbles div {
  position: absolute;
  left: 30%;
  border-radius: 50% 50% 0 50%;
  background: var(--tube-color);
  width: 10px;
  height: 10px;
  opacity: 0.8;
  bottom: calc(var(--tube-percentage) / 3);
  animation: bubble 3s infinite linear;
  transform: scale(0.3) rotate(50deg);
  transition: 1s;
}

.tube .bubbles div:nth-child(2) {
  left: 40%;
  opacity: 0.7;
  animation-delay: 100ms;
  animation-duration: 2.5s;
}

.tube .bubbles div:nth-child(3) {
  left: 40%;
  opacity: 0.6;
  animation-delay: 200ms;
}

.tube .bubbles div:nth-child(4) {
  left: 60%;
  animation-delay: 250ms;
  animation-duration: 1.75s;
}

.tube .bubbles div:nth-child(5) {
  left: 50%;
  opacity: 0.8;
  animation-delay: 150ms;
  animation-duration: 2.25s;
}

.tube .meter {
  position: absolute;
  height: 80%;
  right: 0;
  bottom: 0;
  width: 100%;
}

.tube .meter::after,
.tube .meter::before {
  content: var(--tube-title);
  position: inherit;
  left: 100%;
  margin-left: 10px;
  bottom: var(--tube-percentage);
  transform: translateY(50%);
  background: var(--tube-color);
  color: #1D1D19;
  padding: 10px;
  font-size: 20px;
  font-weight: bold;
  border-radius: 50%;
  transition: 1s;
}

.tube .meter::after {
  content: '';
  border: 12px solid transparent;
  border-right-color: var(--tube-color);
  padding: 0;
  border-radius: 0;
  background: transparent;
  transform: translate(-78%, 50%);
}

.tube .meter div {
  position: absolute;
  left: -4px;
  top: 0;
  font-size: 12px;
  padding: 6px 2px 6px 4px;
  color: #65665f;
  border-top: 1px solid #65665f;
  transform: translateX(-100%);
}

.tube .meter div:nth-child(2) {
  top: 20%;
}

.tube .meter div:nth-child(3) {
  top: 40%;
}

.tube .meter div:nth-child(4) {
  top: 60%;
}

.tube .meter div:nth-child(5) {
  top: 80%;
}

.tube .meter div:nth-child(6) {
  top: 100%;
}