ol {
  margin: 0;
  list-style: none;
  padding: 0;
  --hue: 1;
  --unit: 1rem;
}

.event-date {
  margin: 0 0 0.25rem;
  font-weight: bold;
}
.event-description {
  margin: 0;
}
.timeline li {
  --height: 7rem;
  position: relative;
  display: block;
  background-color: hsl(calc(var(--hue) * 132 / 20), 72%, 47%);
  border-color: hsl(calc(var(--hue) * 132 / 20), 72%, 47%);
  padding: 20px;
  margin: 10px 0; 
  color: #ffffff;
}
.timeline li::before {
  content: "";
  background-color: inherit;
  position: absolute;
  display: block;
  width: var(--unit);
  height: var(--unit);
  top: 100%;
  left: calc(50% - (var(--unit)/2));
}
.timeline li::after {
  content: "";
  position: absolute;
  display: block;
  top: calc(100% + var(--unit));
  left: calc(50% - (var(--unit)));
  border: var(--unit) solid transparent;
  border-top-color: inherit;
}
.timeline li:last-child::before,
.timeline li:last-child::after {
  content: none;
}
.timeline li:nth-child(20n+1){
  --hue: 1;
}
.timeline li:nth-child(20n+2){
  --hue: 2;
}
.timeline li:nth-child(20n+3){
  --hue: 3;
}
.timeline li:nth-child(20n+4){
  --hue: 4;
}
.timeline li:nth-child(20n+5){
  --hue: 5;
}
.timeline li:nth-child(20n+6){
  --hue: 6;
}
.timeline li:nth-child(20n+7){
  --hue: 7;
}
.timeline li:nth-child(20n+8){
  --hue: 8;
}
.timeline li:nth-child(20n+9){
  --hue: 9;
}
/*li:nth-child(20n+10){
  --hue: 10;
}
li:nth-child(20n+11){
  --hue: 11;
}
li:nth-child(20n+12){
  --hue: 12;
}
li:nth-child(20n+13){
  --hue: 13;
}
li:nth-child(20n+14){
  --hue: 14;
}
li:nth-child(20n+15){
  --hue: 15;
}
li:nth-child(20n+16){
  --hue: 16;
}
li:nth-child(20n+17){
  --hue: 17;
}
li:nth-child(20n+18){
  --hue: 18;
}
li:nth-child(20n+19){
  --hue: 19;
}
li:nth-child(20n+20){
  --hue: 20;
}*/
@media (min-width: 550px) and (max-width: 899px){
  .timeline li {
    margin: 1rem;
    width: calc(50% - 4rem);
    float: left;
    min-height: var(--height);
  }
  .timeline li:nth-child(4n+3),
  .timeline li:nth-child(4n+4) {
    float: right;
  }
  .timeline li:nth-child(4n+1)::before {
    top: calc(var(--height)/2 + var(--unit)/2);
    left: 100%;
  }
  .timeline li:nth-child(4n+1)::after {
    top: calc(var(--height)/2);
    left: calc(100% + (var(--unit)));
    border: var(--unit) solid transparent;
    border-left-color: inherit;
  }
  .timeline li:nth-child(4n+3)::before {
    top: calc(var(--height)/2 + var(--unit)/2);
    left: -1rem;
  }
  .timeline li:nth-child(4n+3)::after {
    top: calc(var(--height)/2);
    left: -3rem;
    border: var(--unit) solid transparent;
    border-right-color: inherit;
  }
}
@media (min-width: 900px) and (max-width: 1199px){
  .timeline li {
    margin: 1rem;
    width: calc(33.33% - 4rem);
    float: left;
    min-height: 7rem;
  }
  .timeline li:nth-child(6n+4),
  .timeline li:nth-child(6n+5),
  .timeline li:nth-child(6n+6) {
    float: right;
  }
  .timeline li:nth-child(6n+1)::before,
  .timeline li:nth-child(6n+2)::before {
    top: calc(var(--height)/2 + var(--unit)/2);
    left: 100%;
  }
  .timeline li:nth-child(6n+1)::after,
  .timeline li:nth-child(6n+2)::after {
    top: 3.5rem;
    left: calc(100% + (var(--unit)));
    border: var(--unit) solid transparent;
    border-left-color: inherit;
  }
  .timeline li:nth-child(6n+4)::before,
  .timeline li:nth-child(6n+5)::before{
    top: calc(var(--height)/2 + var(--unit)/2);
    left: -1rem;
  }
  .timeline li:nth-child(6n+4)::after,
  .timeline li:nth-child(6n+5)::after{
    top: calc(var(--height)/2);
    left: -3rem;
    border: var(--unit) solid transparent;
    border-right-color: inherit;
  }
}
@media (min-width: 1200px){
  /*ol {
    max-width: 1600px;
    margin: 0 auto;
  }*/
  .timeline li {
        margin: 1rem;
        width: calc(25% - 2rem);
        float: left;
        min-height: 7rem;
    }
  .timeline li:nth-child(8n+5),
  .timeline li:nth-child(8n+6),
  .timeline li:nth-child(8n+7),
  .timeline li:nth-child(8n+8){
    float: right;
  }
  .timeline li:nth-child(8n+1)::before,
  .timeline li:nth-child(8n+2)::before,
  .timeline li:nth-child(8n+3)::before{
    top: calc(var(--height)/2 + var(--unit)/2);
    left: 100%;
  }
  .timeline li:nth-child(8n+1)::after,
  .timeline li:nth-child(8n+2)::after,
  .timeline li:nth-child(8n+3)::after{
    top: calc(var(--height)/2);
    left: calc(100% + (var(--unit)));
    border: var(--unit) solid transparent;
    border-left-color: inherit;
  }
  .timeline li:nth-child(8n+5)::before,
  .timeline li:nth-child(8n+6)::before,
  .timeline li:nth-child(8n+7)::before {
    top: calc(var(--height)/2 + var(--unit)/2);
    left: -1rem;
  }
  .timeline li:nth-child(8n+5)::after,
  .timeline li:nth-child(8n+6)::after,
  .timeline li:nth-child(8n+7)::after {
    top: calc(var(--height)/2);
    left: -3rem;
    border: var(--unit) solid transparent;
    border-right-color: inherit;
  }
}