.timeline {
    position: relative;
    padding-left: 40px;
    border-left: 3px solid #e0e0e0;
}
.timeline-item {
    position: relative;
    margin-bottom: 20px;
}
.timeline-item:last-child {
    margin-bottom: 0;
}
.timeline-item::before {
    content: '';
    position: absolute;
    left: -51px;
    top: 3px;
    width: 20px;
    height: 20px;
    background-color: #e0e0e0;
    border-radius: 50%;
    z-index: 1;
}
.timeline-item.active::before {
    background-color: #4caf50; /* Green */
}
.timeline-item.in-progress::before {
    background-color: #3f51b5; /* Blue */
}
.timeline-item.pending::before {
    background-color: #ffc107; /* Yellow */
}
.timeline-item.disabled::before {
    background-color: #bdbdbd; /* Gray */
}