html, body {
  --color: #FAC300;
  --icon-width: 60px;
  --text-width: 90px;
  --padding: 2.5rem;
  --duration: 0.2s;
  font-family: sans-serif;
  background-color: var(--color);
  height: 100%;
  margin: 0;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.bar {
  width: calc(var(--icon-width) + var(--text-width));
  height: calc(100% - var(--padding));
  background-color: var(--color);
  position: absolute;
  top: calc(var(--padding) * 0.5);
  left: calc(var(--padding) * 0.5);
  border-radius: var(--icon-width);
  transform: translatex(calc(var(--icon-width) * var(--active)));
  transition: transform var(--duration) ease-in-out;
}

ul {
  list-style: none;
  background-color: white;
  margin: 0;
  padding: var(--padding) calc(var(--padding) / 2);
  position: relative;
  padding-right: calc(var(--text-width) + var(--padding) / 2);
  box-shadow: 0px 0px 15px rgba(0, 0, 0, 0.2);
  display: grid;
  grid-auto-flow: column;
}

li {
  position: relative;
}
li > * {
  display: flex;
  justify-content: flex-start;
  align-items: center;
  height: 0;
}
li .icon {
  z-index: 100;
  justify-content: center;
  width: var(--icon-width);
  cursor: pointer;
  text-align: center;
  opacity: 0.3;
  transition-property: opacity, transform;
  transition-duration: var(--duration);
  transition-timing-function: ease-in-out;
}
li .text {
  position: absolute;
  left: 0;
  top: 0;
  opacity: 0;
  width: var(--text-width);
  margin-left: var(--icon-width);
  pointer-events: none;
  transition: opacity var(--duration) ease-in-out;
  height: 100%;
  font-size: 0.9rem;
  font-weight: bold;
}
li[data-active] .text, li[data-active] .icon {
  opacity: 1;
}

[data-active] ~ li .icon {
  transform: translatex(calc((var(--i) * 1px) + var(--text-width)));
}