/* credit to https://codepen.io/bisserof/pen/fdtBm for original idea */
.tree {
    margin: 1em;
    padding-left: 3px;
}

.tree input {
    position: absolute;
    clip: rect(0, 0, 0, 0);
}

.tree input ~ ul {
    display: none;
}

.tree input:checked ~ ul {
    display: block;
}

.tree ul {
    padding-left: 0;
}

.tree span.highlight,
.tree span.highlight a {
    color: #f6ffd9;
}
.tree span.highlight:hover,
.tree span.highlight a:hover {
    color: #c3ec41;
}

/* rows */

.tree li {
    line-height: 1.2;
    position: relative;
    padding: 0 0 1em 1em;
}

.tree ul li {
    padding: 0.8em 0 0 1em;
    list-style: none;
}

.tree > li:last-child {
    padding-bottom: 0;
}

/* labels */

.tree_label {
    position: relative;
    display: inline-block;
}

label.tree_label {
    cursor: pointer;
}
label.tree_label:hover {
    color: #666;
}

/* expanded icon */

label.tree_label::before {
    background: #606777;
    color: #fff;
    position: relative;
    z-index: 1;
    float: left;
    margin: 0 1em 0 -2.15em;
    width: 1em;
    height: 1em;
    border-radius: 1em;
    content: '+';
    text-align: center;
    line-height: .9em;
}

:checked ~ label.tree_label::before {
    content: '-';
    background: #566990;
}

:hover ~ label.tree_label::before {
    background: #6683c5;
}

/* branches */

.tree li::before {
    position: absolute;
    top: 0;
    bottom: 0;
    left: -.5em;
    display: block;
    width: 0;
    border-left: 1px solid #777;
    content: "";
}

.tree_label::after {
    position: absolute;
    top: 0;
    left: -1.5em;
    display: block;
    height: 0.5em;
    width: 1em;
    border-bottom: 1px solid #777;
    border-left: 1px solid #777;
    border-radius: 0 0 0 .3em;
    content: "";
}

label.tree_label::after {
    border-bottom: 0;
}

:checked ~ label.tree_label::after {
    border-radius: 0 .3em 0 0;
    border-top: 1px solid #777;
    border-right: 1px solid #777;
    border-bottom: 0;
    border-left: 0;
    bottom: 0;
    top: 0.5em;
    height: auto;
}

.tree li:last-child::before {
    height: 1em;
    bottom: auto;
}

.tree > li:last-child::before {
    display: none;
}

.tree_custom {
    display: block;
    background: #a1a1a1;
    padding: 1em;
    border-radius: 0.3em;
}