css_tree.scss

$css-tree-distance: 8px;
$css-tree-border: 1px solid var(--light-gray-color-80);

.css-tree {
    &, ul {
        list-style: none;
        margin: 0;
        padding: 0;
    }
    ul {
        margin-left: $css-tree-distance;
        position: relative;

        &:before {
            border-left: $css-tree-border;
            content: '';
            display: block;
            position: absolute;
            top: 0;
            bottom: 0;
            left: 0;
            width: 0;
        }
    }
    li {
        overflow: hidden;
        padding-left: ($css-tree-distance + 2px);
        position: relative;

        &.css-tree-hidden {
            display: none;
        }
    }
    ul li:before {
        content: '';
        display: block;
        height: 0;
        width: $css-tree-distance;
        position: absolute;
        border-top: $css-tree-border;
        left: 0;
        top: $css-tree-distance;
    }
    ul li:last-child:before {
        background: var(--white);
        height: auto;
        top: 10px;
        bottom: 0;
    }
}
.css-tree.collapsable {
    input[type=checkbox] {
        display: none;
        + label {
            @include icon(before, arr_1right, clickable);
            cursor: pointer;

            &:before {
                transition: transform var(--transition-duration);
                vertical-align: baseline;
            }
        }
        ~ ul {
            max-height: 0;
            opacity: 0;

            transition: all var(--transition-duration);
        }
        ~ input[type=radio] + label {
            margin-left: 0;