Zig-zag timeline layout from https://bootsnipp.com/snippets/featured/zigzag-timeline-layout by https://bootsnipp.com/andrewnite.

zig-zag-timeline.css

.timeline {
    position: relative;
    padding:4px 0 0 0;
    margin-top:22px;
    list-style: none;
}

.timeline>li:nth-child(even) {
    position: relative;
    margin-bottom: 50px;
    height: 180px;
    right:-100px;
}

.timeline>li:nth-child(odd) {
    position: relative;
    margin-bottom: 50px;
    height: 180px;
    left:-100px;
}

.timeline>li:before,
.timeline>li:after {
    content: " ";
    display: table;
}

.timeline>li:after {
    clear: both;
    min-height: 170px;
}

.timeline > li .timeline-panel {
  position: relative;
  float: left;
  width: 41%;
  padding: 0 20px 20px 30px;
  text-align: right;
}

.timeline>li .timeline-panel:before {
    right: auto;
    left: -15px;
    border-right-width: 15px;
    border-left-width: 0;
}

.timeline>li .timeline-panel:after {
    right: auto;
    left: -14px;
    border-right-width: 14px;
    border-left-width: 0;
}

.timeline>li .timeline-image {
    z-index: 100;
    position: absolute;
    left: 50%;
    border: 7px solid #3b5998;
    border-radius: 100%;
    background-color: #3b5998;
    box-shadow: 0 0 5px #4582ec;
    width: 200px;
    height: 200px;
    margin-left: -100px;
}

.timeline>li .timeline-image h4 {
    margin-top: 12px;
    font-size: 10px;
    line-height: 14px;
}

.timeline>li.timeline-inverted>.timeline-panel {
    float: right;
    padding: 0 30px 20px 20px;
    text-align: left;
}

.timeline>li.timeline-inverted>.timeline-panel:before {
    right: auto;
    left: -15px;
    border-right-width: 15px;
    border-left-width: 0;
}

.timeline>li.timeline-inverted>.timeline-panel:after {
    right: auto;
    left: -14px;
    border-right-width: 14px;
    border-left-width: 0;
}

.timeline>li:last-child {
    margin-bottom: 0;
}

.timeline .timeline-heading h4 {
  margin-top:22px;
    margin-bottom: 4px;
    padding:0;
    color: #b3b3b3;
}

.timeline .timeline-heading h4.subheading {
  margin:0;
  padding:0;
    text-transform: none;
    font-size:18px;
    color:#333333;
}

.timeline .timeline-body>p,
.timeline .timeline-body>ul {
    margin-bottom: 0;
    color:#808080;
}
/*Style for even div.line*/
.timeline>li:nth-child(odd) .line:before {
    content: "";
    position: absolute;
    top: 60px;
    bottom: 0;
    left: 690px;
    width: 4px;
    height:340px;
    background-color: #3b5998;
    -ms-transform: rotate(-44deg); /* IE 9 */
    -webkit-transform: rotate(-44deg); /* Safari */
    transform: rotate(-44deg);
    box-shadow: 0 0 5px #4582ec;
}
/*Style for odd div.line*/
.timeline>li:nth-child(even) .line:before  {
    content: "";
    position: absolute;
    top: 60px;
    bottom: 0;
    left: 450px;
    width: 4px;
    height:340px;
    background-color: #3b5998;
    -ms-transform: rotate(44deg); /* IE 9 */
    -webkit-transform: rotate(44deg); /* Safari */
    transform: rotate(44deg);
    box-shadow: 0 0 5px #4582ec;
}
/* Medium Devices, .visible-md-* */
@media (min-width: 992px) and (max-width: 1199px) {
  .timeline > li:nth-child(even) {
    margin-bottom: 0px;
    min-height: 0px;
    right: 0px;
  }
  .timeline > li:nth-child(odd) {
    margin-bottom: 0px;
    min-height: 0px;
    left: 0px;
  }
  .timeline>li:nth-child(even) .timeline-image {
    left: 0;
    margin-left: 0px;
  }
  .timeline>li:nth-child(odd) .timeline-image {
    left: 690px;
    margin-left: 0px;
  }
  .timeline > li:nth-child(even) .timeline-panel {
    width: 76%;
    padding: 0 0 20px 0px;
    text-align: left;
  }
  .timeline > li:nth-child(odd) .timeline-panel {
    width: 70%;
    padding: 0 0 20px 0px;
    text-align: right;
  }
  .timeline > li .line {
    display: none;
  }
}
/* Small Devices, Tablets */
@media (min-width: 768px) and (max-width: 991px) {
  .timeline > li:nth-child(even) {
    margin-bottom: 0px;
    min-height: 0px;
    right: 0px;
  }
  .timeline > li:nth-child(odd) {
    margin-bottom: 0px;
    min-height: 0px;
    left: 0px;
  }
  .timeline>li:nth-child(even) .timeline-image {
    left: 0;
    margin-left: 0px;
  }
  .timeline>li:nth-child(odd) .timeline-image {
    left: 520px;
    margin-left: 0px;
  }
  .timeline > li:nth-child(even) .timeline-panel {
    width: 70%;
    padding: 0 0 20px 0px;
    text-align: left;
  }
  .timeline > li:nth-child(odd) .timeline-panel {
    width: 70%;
    padding: 0 0 20px 0px;
    text-align: right;
  }
  .timeline > li .line {
    display: none;
  }
}
/* Custom, iPhone Retina */
@media only screen and (max-width: 767px) {
  .timeline > li:nth-child(even) {
    margin-bottom: 0px;
    min-height: 0px;
    right: 0px;
  }
  .timeline > li:nth-child(odd) {
    margin-bottom: 0px;
    min-height: 0px;
    left: 0px;
  }
  .timeline>li .timeline-image {
    position: static;
    width: 150px;
    height: 150px;
    margin-bottom:0px;
  }
  .timeline>li:nth-child(even) .timeline-image {
    left: 0;
    margin-left: 0;
  }
  .timeline>li:nth-child(odd) .timeline-image {
    float:right;
    left: 0px;
    margin-left:0;
  }
  .timeline > li:nth-child(even) .timeline-panel {
    width: 100%;
    padding: 0 0 20px 14px;
  }
  .timeline > li:nth-child(odd) .timeline-panel {
    width: 100%;
    padding: 0 14px 20px 0px;
  }
  .timeline > li .line {
    display: none;
  }
}