@css-tree-delay: 300ms;
@css-tree-distance: 8px;
@css-tree-border: 1px solid @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: #fff;
        height: auto;
        top: 10px;
        bottom: 0;
    }
}
.css-tree.collapsable {
    input[type=checkbox] {
        display: none;
        + label {
            .icon('before', 'arr_1right', 'clickable');
            cursor: pointer;

            &:before {
                transition: transform @css-tree-delay;
                vertical-align: baseline;
            }
        }
        ~ ul {
            max-height: 0;
            opacity: 0;

            transition: all @css-tree-delay;
        }
        ~ input[type=radio] + label {
            margin-left: 0;
        }

        &:checked {
            + label::before {
                transform: rotate(90deg);
            }
            ~ ul {
                max-height: 10000px;
                opacity: 1;
            }
        }
    }
}
.css-tree.selectable {
    input[type=checkbox] {
        + label {
            .hide-text();
        }
        ~ input[type=radio] + label {
            margin-left: 0;
        }
    }

    input[type=radio] {
        display: none;

        + label {
            color: @brand-color-dark;
            border-radius: 2px;
            cursor: pointer;
            padding: 0 3px;
            margin-left: 1px;
        }

        &:checked + label {
            font-weight: bold;
            background: @content-color-40;
        }

        &[disabled] + label {
            color: #888;
        }
    }
}