timeline.css

.timeline {
    position: relative;
    width: 660px;
    margin: 0 auto;
    margin-top: 150px;
    padding: 1em 0;
    list-style-type: none;
}

.timeline:before {
    position: absolute;
    left: 50%;
    top: 0;
    content: ' ';
    display: block;
    width: 6px;
    height: 100%;
    margin-left: -3px;
    background: rgb(80, 80, 80);
    background: -moz-linear-gradient(top, rgba(80, 80, 80, 0) 0%, rgb(80, 80, 80) 8%, rgb(80, 80, 80) 92%, rgba(80, 80, 80, 0) 100%);
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(30, 87, 153, 1)), color-stop(100%, rgba(125, 185, 232, 1)));
    background: -webkit-linear-gradient(top, rgba(80, 80, 80, 0) 0%, rgb(80, 80, 80) 8%, rgb(80, 80, 80) 92%, rgba(80, 80, 80, 0) 100%);
    background: -o-linear-gradient(top, rgba(80, 80, 80, 0) 0%, rgb(80, 80, 80) 8%, rgb(80, 80, 80) 92%, rgba(80, 80, 80, 0) 100%);
    background: -ms-linear-gradient(top, rgba(80, 80, 80, 0) 0%, rgb(80, 80, 80) 8%, rgb(80, 80, 80) 92%, rgba(80, 80, 80, 0) 100%);
    background: linear-gradient(to bottom, rgba(80, 80, 80, 0) 0%, rgb(80, 80, 80) 8%, rgb(80, 80, 80) 92%, rgba(80, 80, 80, 0) 100%);

    z-index: 5;
}

.timeline li {
    padding: 1em 0;
}

.timeline li:after {
    content: "";
    display: block;
    height: 0;
    clear: both;
    visibility: hidden;
}

.direction-l {
    position: relative;
    width: 300px;
    float: left;
    text-align: right;
}

.direction-r {
    position: relative;
    width: 300px;
    float: right;
}

.flag-wrapper {
    position: relative;
    display: inline-block;

    text-align: center;
}

.flag {
    position: relative;
    display: inline;
    background: rgb(248, 248, 248);
    padding: 6px 10px;
    border-radius: 5px;
    color: black;
    font-weight: 600;
    text-align: left;
}

.direction-l .flag {
    -webkit-box-shadow: -1px 1px 1px rgba(0, 0, 0, 0.15), 0 0 1px rgba(0, 0, 0, 0.15);
    -moz-box-shadow: -1px 1px 1px rgba(0, 0, 0, 0.15), 0 0 1px rgba(0, 0, 0, 0.15);
    box-shadow: -1px 1px 1px rgba(0, 0, 0, 0.15), 0 0 1px rgba(0, 0, 0, 0.15);
}

.direction-r .flag {
    -webkit-box-shadow: 1px 1px 1px rgba(0, 0, 0, 0.15), 0 0 1px rgba(0, 0, 0, 0.15);
    -moz-box-shadow: 1px 1px 1px rgba(0, 0, 0, 0.15), 0 0 1px rgba(0, 0, 0, 0.15);
    box-shadow: 1px 1px 1px rgba(0, 0, 0, 0.15), 0 0 1px rgba(0, 0, 0, 0.15);
}

.direction-l .flag:before,
.direction-r .flag:before {
    position: absolute;
    top: 50%;
    right: -40px;
    content: ' ';
    display: block;
    width: 12px;
    height: 12px;
    margin-top: -10px;
    background: #fff;
    border-radius: 10px;
    border: 4px solid var(--color-30);
    z-index: 10;
}

.direction-r .flag:before {
    left: -40px;
}

.direction-l .flag:after {
    content: "";
    position: absolute;
    left: 100%;
    top: 50%;
    height: 0;
    width: 0;
    margin-top: -8px;
    border: solid transparent;
    border-left-color: rgb(248, 248, 248);
    border-width: 8px;
    pointer-events: none;
}

.direction-r .flag:after {
    content: "";
    position: absolute;
    right: 100%;
    top: 50%;
    height: 0;
    width: 0;
    margin-top: -8px;
    border: solid transparent;
    border-right-color: rgb(248, 248, 248);
    border-width: 8px;
    pointer-events: none;
}

.time-wrapper {
    display: inline;

    line-height: 1em;
    font-size: 0.66666em;
    color: var(--color-30);
    vertical-align: middle;
}

.direction-l .time-wrapper {
    float: left;
}

.direction-r .time-wrapper {
    float: right;
}

.time {
    display: inline-block;
    padding: 4px 6px;
    background: rgb(248, 248, 248);
}

.desc {
    margin: 1em 0.75em 0 0;
    color: var(--font-color);
    font-size: 0.77777em;
    font-style: italic;
    line-height: 1.5em;
}

.direction-r .desc {
    margin: 1em 0 0 0.75em;
}

/* ================ Timeline Media Queries ================ */

@media screen and (max-width: 660px) {

    .timeline {
        width: 100%;
        padding: 4em 0 1em 0;
    }

    .timeline li {
        padding: 2em 0;
    }

    .direction-l,
    .direction-r {
        float: none;
        width: 100%;

        text-align: center;
    }

    .flag-wrapper {
        text-align: center;
    }

    .flag {
        background: white;
        z-index: 15;
    }

    .direction-l .flag:before,
    .direction-r .flag:before {
        position: absolute;
        top: -30px;
        left: 50%;
        content: ' ';
        display: block;
        width: 12px;
        height: 12px;
        margin-left: -9px;
        background: var(--color-10);
        border-radius: 10px;
        border: 4px solid var(--color-30);
        z-index: 10;
    }

    .direction-l .flag:after,
    .direction-r .flag:after {
        content: "";
        position: absolute;
        left: 50%;
        top: -8px;
        height: 0;
        width: 0;
        margin-left: -8px;
        border: solid transparent;
        border-bottom-color: white;
        border-width: 8px;
        pointer-events: none;
    }

    .time-wrapper {
        display: block;
        position: relative;
        margin: 4px 0 0 0;
        z-index: 14;
    }

    .direction-l .time-wrapper {
        float: none;
    }

    .direction-r .time-wrapper {
        float: none;
    }

    .desc {
        position: relative;
        margin: 1em 0 0 0;
        padding: 1em;
        background: var(--color-20);
        -webkit-box-shadow: 0 0 1px rgba(0, 0, 0, 0.20);
        -moz-box-shadow: 0 0 1px rgba(0, 0, 0, 0.20);
        box-shadow: 0 0 1px rgba(0, 0, 0, 0.20);

        z-index: 15;
    }

    .direction-l .desc,
    .direction-r .desc {
        position: relative;
        margin: 1em 1em 0 1em;
        padding: 1em;

        z-index: 15;
    }

}

@media screen and (min-width: 400px) and (max-width: 660px) {

    .direction-l .desc,
    .direction-r .desc {
        margin: 1em 4em 0 4em;
    }

}