body {
  font-family: 'Source Sans Pro',Helvetica Neue,Helvetica,Arial,sans-serif;
  font-size: 16px;
  line-height: 1.75;
}

#timeline {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  background-color: rgba(232, 244, 248, 0.041);
}
#timeline:hover .tl-item {
  width: 23.3333%;
}

.tl-item {
  -webkit-transform: translate3d(0, 0, 0);
          transform: translate3d(0, 0, 0);
  position: relative;
  width: 25%;
  height: 50vh;
  min-height: 300px;
  color: #ffffff;
  overflow: hidden;
  -webkit-transition: width 0.5s ease;
  transition: width 0.5s ease;
}
.tl-item:before, .tl-item:after {
  -webkit-transform: translate3d(0, 0, 0);
          transform: translate3d(0, 0, 0);
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
}
.tl-item:after {
  background: rgba(3, 22, 37, 0.85);
  opacity: 1;
  -webkit-transition: opacity 0.5s ease;
  transition: opacity 0.5s ease;
}
.tl-item:before {
  background: -webkit-linear-gradient(top, transparent 0%, rgb(58, 126, 204) 75%);
  background: linear-gradient(to bottom, transparent 0%, rgb(11, 83, 131) 75%);
  z-index: 1;
  opacity: 0;
  -webkit-transform: translate3d(0, 0, 0) translateY(50%);
          transform: translate3d(0, 0, 0) translateY(50%);
  -webkit-transition: opacity 0.5s ease, -webkit-transform 0.5s ease;
  transition: opacity 0.5s ease, -webkit-transform 0.5s ease;
  transition: opacity 0.5s ease, transform 0.5s ease;
  transition: opacity 0.5s ease, transform 0.5s ease, -webkit-transform 0.5s ease;
}
.tl-item:hover {
  width: 30% !important;
}
.tl-item:hover:after {
  opacity: 0;
}
.tl-item:hover:before {
  opacity: 1;
  -webkit-transform: translate3d(0, 0, 0) translateY(0);
          transform: translate3d(0, 0, 0) translateY(0);
  -webkit-transition: opacity 1s ease, -webkit-transform 1s ease 0.25s;
  transition: opacity 1s ease, -webkit-transform 1s ease 0.25s;
  transition: opacity 1s ease, transform 1s ease 0.25s;
  transition: opacity 1s ease, transform 1s ease 0.25s, -webkit-transform 1s ease 0.25s;
}
.tl-item:hover .tl-content {
  opacity: 1;
  -webkit-transform: translateY(0);
          transform: translateY(0);
  -webkit-transition: all 0.75s ease 0.5s;
  transition: all 0.75s ease 0.5s;
}
.tl-item:hover .tl-bg {
  -webkit-filter: grayscale(0);
          filter: grayscale(0);
}

.tl-content {
  -webkit-transform: translate3d(0, 0, 0) translateY(25px);
          transform: translate3d(0, 0, 0) translateY(25px);
  position: relative;
  z-index: 1;
  text-align: center;
  margin: 0 1.618em;
  top: 30%;
  opacity: 0;
}
.tl-content h1 {
  font-family: 'Pathway Gothic One',Helvetica Neue,Helvetica,Arial,sans-serif;
  text-transform: uppercase;
  color: #17cf64;
  font-size: 1.44rem;
  font-weight: normal;
}

.tl-year {
  position: absolute;
  top: 20%;
  left: 50%;
  -webkit-transform: translateX(-50%) translateY(-50%);
          transform: translateX(-50%) translateY(-50%);
  z-index: 1;
}
.tl-year p {
  font-family: 'Pathway Gothic One',Helvetica Neue,Helvetica,Arial,sans-serif;
  font-size: 1.728rem;
  line-height: 0;
}

.tl-bg {
  -webkit-transform: translate3d(0, 0, 0);
          transform: translate3d(0, 0, 0);
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  background-size: cover;
  background-position: center center;
  -webkit-transition: -webkit-filter 0.5s ease;
  transition: -webkit-filter 0.5s ease;
  transition: filter 0.5s ease;
  transition: filter 0.5s ease, -webkit-filter 0.5s ease;
  -webkit-filter: grayscale(100%);
          filter: grayscale(100%);
}