slider.css

#pl-comprehension {
  position: absolute;
  top: 64px;
  left: 16px;
  width: 97px;
  padding: 20px;
  background: rgba(0, 0, 0, 0.6);
  border-radius: 4px;
  opacity: 0.3;
  transition: opacity 0.3s;
}

#pl-comprehension:hover {
  opacity: 1;
}

#pl-comprehension-container {
  display: flex;
}

#pl-comprehension-title {
  font-size: 14px;
  font-weight: 500;
  color: rgb(203, 203, 203);
  margin-bottom: 10px;
}

#pl-comprehension-slider {
  display: flex;
}

#pl-slider-clip {
  width: 30px;
  height: 150px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

#pl-slider-labels {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

#pl-slider-labels p {
  color: white;
  font-size: 16px;
}

#pl-slider-elmt {
  -webkit-appearance: none;
  padding: 18px 0;
  width: 150px;
  height: 30px;
  background: transparent;
  transform: rotate(-90deg) translateY(-100%);
}

#pl-slider-elmt:focus {
  outline: none; /* Removes the blue border. You should probably do some kind of focus styling for accessibility reasons though. */
}

#pl-slider-elmt::-webkit-slider-thumb {
  -webkit-appearance: none;
  -webkit-appearance: none;
  border: 2px solid white;
  height: 20px;
  width: 20px;
  border-radius: 50%;
  background: #dfdfdf;
  cursor: ns-resize;
  margin-top: -6px; /* You need to specify a margin in Chrome, but in Firefox and IE it is automatic */
}

#pl-slider-elmt::-webkit-slider-runnable-track {
  height: 8.4px;
  cursor: pointer;
  background: linear-gradient(to left, #e66465, #9198e5);
  border-radius: 4.2px;
  border: 0.2px solid rgba(255, 255, 255, 0.4);
}