Trilium/apps/client/src/widgets/react/Card.css

:where(.tn-card) {
    --card-border-radius: 8px;
    --card-padding-block: 8px;
    --card-padding-inline: 16px;
    --card-section-gap: 3px;
    --card-nested-section-indent: 30px;
}

.tn-card-heading {
    margin-bottom: 10px;
    font-size: .75rem;
    font-weight: 600;
    letter-spacing: .4pt;
    text-transform: uppercase;
}

.tn-card {
    display: flex;
    flex-direction: column;
    gap: var(--card-section-gap);

    .tn-card-section {
        padding: var(--card-padding-block) var(--card-padding-inline);
        border: 1px solid var(--card-border-color, var(--main-border-color));
        background: var(--card-background-color);

        &:first-of-type {
            border-top-left-radius: var(--card-border-radius);
            border-top-right-radius: var(--card-border-radius);
        }

        &:last-of-type {
            border-bottom-left-radius: var(--card-border-radius);
            border-bottom-right-radius: var(--card-border-radius);
        }

        &.tn-card-section-nested {
            padding-left: calc(var(--card-padding-inline) + var(--card-nested-section-indent) * var(--tn-card-section-nesting-level));
            background-color: color-mix(in srgb, var(--card-background-color) calc(100% / (var(--tn-card-section-nesting-level) + 1)) , transparent);
        }

        &.tn-card-section-highlight-on-hover:hover {
            background-color: var(--card-background-hover-color);
            transition: background-color .2s ease-out;
        }

    }
}