.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
    padding: 10px;
    list-style: none;
}
.timeline:before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 50%;
    margin-left: -1px;
    width: 2px;
    background-color: #e9e9e9;
}
.timeline-item {
    padding: 20px;
    position: relative;
    width: 50%;
    left: 50%;
    margin-bottom: 20px;
    background-color: #ffffff;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    border-radius: 4px;
}
.timeline-item:nth-child(odd) {
    left: 0;
}
.timeline-item::after {
    content: '';
    position: absolute;
    width: 0;
    height: 0;
    border-style: solid;
    top: 20px;
}
.timeline-item:nth-child(even)::after {
    left: -8px;
    border-width: 8px 8px 8px 0;
    border-color: transparent #ffffff transparent transparent;
}
.timeline-item:nth-child(odd)::after {
    right: -8px;
    border-width: 8px 0 8px 8px;
    border-color: transparent transparent transparent #ffffff;
}
.timeline-item time {
    display: block;
    font-size: 1.1em;
    font-weight: bold;
    margin-bottom: 10px;
}
.timeline-item p {
    margin: 0;
}