* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.container {
  display: flex;
  flex-direction: row;
  justify-content: space-around;
  height: 550px;
  align-items: flex-end;
}
.tube {
  width: 50px;
  height: 500px;
  border-style: solid;
  border-width: 0 5px 5px 5px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  position: relative;
  border-bottom-left-radius: 20px;
  border-bottom-right-radius: 20px;
}
/* .tube-red {
  border-color: red;
}
.tube-green {
  border-color: green;
}
.tube-blue {
  border-color: blue;
} */
.ball {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  /* border-style: solid; */
  /* border-width: 2px; */
}
.ball-red {
  /* background-color: lightcoral; */
  /* border-color: red; */
  background: radial-gradient(circle, red 30%, darkred 70%);
}
.ball-green {
  /* background-color: lightgreen; */
  /* border-color: green; */
  background: radial-gradient(circle, green 30%, darkgreen 70%);
}
.ball-blue {
  /* background-color: lightskyblue; */
  /* border-color: blue; */
  background: radial-gradient(circle, blue 30%, darkblue 70%);
}
.ball-float {
  position: absolute;
  top: -40px;
}

@media only screen and (min-width: 600px) {
  .container {
    justify-content: center;
    gap: 100px;
  }
}