treehouse/static/css/new.css

/* Give the intro and outro some breathing room. */
section {
    padding: 1em 2em;
}

/* Style all links in the last paragraph as big buttons. */
.tree th-bc>p:last-child {
    --transition-duration: 0.2s;

    margin-top: 8px;
    margin-bottom: 4px;

    &>a {
        display: inline-block;

        padding: 0.5em 1.5em;

        color: var(--text-color);
        background-color: transparent;
        border: 1px solid var(--border-1);
        border-radius: 2em;
        text-decoration: none;

        transition:
            color var(--transition-duration),
            background-color var(--transition-duration),
            border-color var(--transition-duration);

        &:hover,
        &:focus {
            color: white;
            background-color: #058ef0;
            border-color: white;
        }
    }
}

.tree li>div:first-child,
.tree li>details>summary:first-child {
    --margin: 2.5em;

    border: none;
    margin-left: var(--tree-indent-width);
    width: calc(100% - var(--tree-indent-width));
    margin-top: var(--margin);
    margin-bottom: var(--margin);
}

.tree th-bp {
    display: none;
}

.tree th-bb {
    opacity: 100%;

    & .branch-date {
        display: block !important;
    }
}

@media (max-width: 600px) {
    .tree .branch-container {
        flex-direction: column-reverse;
    }
}

section[is="th-settings"] {
    & h3 {
        display: inline;
    }

    & details>summary {
        --recursive-wght: 700;

        list-style: none;
        cursor: pointer;

        opacity: 50%;
        transition: opacity var(--transition-duration);

        &::-webkit-details-marker {
            display: none;
        }

        &::before {
            --recursive-casl: 0.0;
            --recursive-mono: 1.0;
            --recursive-slnt: 0.0;

            content: '+';
            margin-right: 0.3em;

            opacity: 50%;
        }

        &:hover {
            opacity: 100%;
        }
    }

    & details[open]>summary {
        opacity: 100%;

        &::before {
            content: '-';
        }
    }

    & p {
        margin-bottom: 8px;
    }

    & button {
        border: 1px solid var(--border-1);
        border-radius: 999px;
        padding: 4px 12px;
        background: none;
        color: var(--text-color);
        font-size: 1rem;

        cursor: pointer;

        transition:
            color var(--transition-duration),
            background-color var(--transition-duration),
            border-color var(--transition-duration);

        &:hover {
            color: white;
            background-color: #058ef0;
            border-color: white;
        }
    }
}