.activity-list {
    margin: 0;
    padding: 0;
    list-style: none;
    display: grid;
    grid-auto-flow: dense;
    grid-template-columns: repeat(auto-fill, minmax( 100px, 1fr));
    grid-gap: 3px;
}

.activity-list li {
    padding: 1px 1px 1px 1px;
    position: relative;
    border: 1px solid black;
    display: inline-block;
    width: 1in;
    color: white;
    text-shadow: 2px 2px #000000;
}

.activity button {
    width: 100%;
    height: 100%;
    border-radius: 5%;
    background-color: rgba(0, 0, 0, 0.5);
}

.activity-icon {
    height: 2em;
    width: 2em;
}

.activity-button.current {
    background-color: lightblue;
    animation-name: tracking;
    animation-duration: 3s;
    animation-iteration-count: infinite;
    animation-timing-function: ease-in-out;
}
@keyframes tracking {
  0% {
    background-color: lightblue;
  }
  50% {
    background-color: orange;
  }
  100 {
    background-color: lightblue;
  }
}