*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

ul.timeline {
    --col-gap: 2rem;
    --row-gap: 2rem;
    --line-w: 0.25rem;
    display: grid;
    grid-template-columns: var(--line-w) 1fr;
    grid-auto-columns: max-content;
    column-gap: var(--col-gap);
    list-style: none;
    width: 80%;
    margin-inline: auto;
}

/* line */
ul.timeline::before {
    content: "";
    grid-column: 1;
    grid-row: 1 / span 20;
    background: rgb(225, 225, 225);
    border-radius: calc(var(--line-w) / 2);
}

/* columns*/

/* row gaps */
ul.timeline>li:not(:last-child) {
    margin-bottom: var(--row-gap);
}

/* card */
ul.timeline li {
    grid-column: 2;
    --inlineP: 1.5rem;
    margin-inline: var(--inlineP);
    grid-row: span 2;
    display: grid;
    grid-template-rows: min-content min-content min-content;
}

/* date */
ul.timeline li .timeline-title {
    --dateH: 3rem;
    height: var(--dateH);
    margin-inline: calc(var(--inlineP) * -1);
    background-color: var(--accent-color);
    color: white;
    font-size: 1rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-inline: 1.5rem;
    position: relative;
    border-radius: calc(var(--dateH) / 2) 0 0 calc(var(--dateH) / 2);
    margin-bottom: 15px;
}

/* date flap */
ul.timeline li .timeline-title::before {
    content: "";
    width: var(--inlineP);
    aspect-ratio: 1;
    background: var(--accent-color);
    background-image: linear-gradient(rgba(0, 0, 0, 0.2) 100%, transparent);
    position: absolute;
    top: 100%;
    clip-path: polygon(0 0, 100% 0, 0 100%);
    right: 0;
}

/* circle */
ul.timeline li .timeline-title::after {
    content: "";
    position: absolute;
    width: 2rem;
    aspect-ratio: 1;
    background: var(--bgColor);
    border: 0.3rem solid var(--accent-color);
    border-radius: 50%;
    top: 50%;
    transform: translate(50%, -50%);
    right: calc(100% + var(--col-gap) + var(--line-w) / 2);
}

/* title description */
ul.timeline li .title,
ul.timeline li .description {
    background: var(--bgColor);
    position: relative;
}

ul.timeline li .title {
    overflow: hidden;
    padding-block-start: 1.5rem;
    padding-block-end: 1rem;
    font-weight: 500;
}

ul.timeline li .description {
    padding-block-end: 1.5rem;
}

/* shadows */
ul.timeline li .title::before,
ul.timeline li .description::before {
    content: "";
    position: absolute;
    width: 90%;
    height: 0.5rem;
    background: rgba(0, 0, 0, 0.5);
    left: 50%;
    border-radius: 50%;
    filter: blur(4px);
    transform: translate(-50%, 50%);
}

ul.timeline li .title::before {
    bottom: calc(100% + 0.125rem);
}

ul.timeline li .description::before {
    z-index: -1;
    bottom: 0.25rem;
}

@media (min-width: 40rem) {
    ul.timeline {
        grid-template-columns: 1fr var(--line-w) 1fr;
    }

    ul.timeline::before {
        grid-column: 2;
    }

    ul.timeline li:nth-child(odd) {
        grid-column: 1;
    }

    ul.timeline li:nth-child(even) {
        grid-column: 3;
    }

    /* start second card */
    ul.timeline li:nth-child(2) {
        grid-row: 2/4;
    }

    ul.timeline li:nth-child(odd) .timeline-title::before {
        clip-path: polygon(0 0, 100% 0, 100% 100%);
        left: 0;
    }

    ul.timeline li:nth-child(odd) .timeline-title::after {
        transform: translate(-50%, -50%);
        left: calc(100% + var(--col-gap) + var(--line-w) / 2);
    }

    ul.timeline li:nth-child(odd) .timeline-title {
        border-radius: 0 calc(var(--dateH) / 2) calc(var(--dateH) / 2) 0;
    }
}

div.description h1 {
    font-size: 16px;
    text-align: left;
    line-height: 1.5em;
}

div.description h2 {
    font-size: 14px;
    margin-bottom: 0;
}

div.description p,
div.description ul li {
    font-size: 12px;
    line-height: 1.5em;
    margin-bottom: 0;
}

div.description hr {
    margin-top: 15px;
    padding-bottom: 5px;
}

/* reset timeline list styles inside descriptioniption blocks */
div.description ul {
    display: block;
    margin: 0 0 0 1.5rem;
    padding: 0;
    width: auto;
    grid-template-columns: none;
    grid-auto-columns: auto;
    column-gap: normal;
}

div.description ul li {
    display: list-item;
    margin-bottom: 0;
    grid-column: auto;
    grid-row: auto;
}

/* first item in description lists: no left margin and no bullet */
div.description ul li {
    list-style: none;
    margin: 0;
    margin-left: -1.5rem;

}

div.description ul li ul li {
    list-style: square;
    margin-left: 1.5rem;
}