.timeline {
    display: block;
    position: relative;
    margin: 50px auto;
    height: 100px;
    width: 90vw;        /* 90% of viewport width */
    max-width: none;
}

/* The line */
.line {
    position: absolute;
    top: 50%;
    left: 0;
    width: 100%;
    height: 4px;
    background-color: #ddd;
    transform: translateY(-50%);
}

/* Markers */
.marker {
    position: absolute;
    top: 50%;
    width: 12px;
    height: 12px;
    background-color: #007BFF;
    border-radius: 50%;
    transform: translate(-50%, -50%); /* center on point */
}

.current-marker {
    background-color: #FF5722;
}

/* Labels */
.timeline-label {
    position: absolute;
    transform: translateX(-50%);
    text-align: center;
    font-size: 12px;
    white-space: nowrap;
}

/* Start + End labels BELOW markers */
#start-label,
#end-label {
    top: calc(50% + 20px); /* 20px below the line */
}

/* Current label ABOVE marker */
#current-label {
    top: calc(50% - 30px); /* 30px above the line */
}