:root {
    --tree-line-color: #ddd;
    --tree-line-alignment: 1.2rem;
}

.checkListControl {
    position: relative;
    padding-left: 1.5rem;
}

.checkListControl:not(.firstLevel)::before {
    content: '';
    position: absolute;
    left: 0.3rem;
    top: 0;
    bottom: 0;
    width: 1px;
    background-color: var(--tree-line-color); /* Line color */
    z-index: 0;
}

.checkListControl.lastItem::before {
    height: 50%;
}

.checkListControl .form-check {
    position: relative;
}

.checkListControl:not(.firstLevel) .form-check::before {
    content: '';
    position: absolute;
    top: 50%;
    left: calc(-1 * var(--tree-line-alignment)); 
    width: var(--tree-line-alignment);
    height: 1px;
    background-color: var(--tree-line-color); /* Line color */
    z-index: 1;
}

.checkListControl:first-child::before {
    display: none;
}