body {
    font-family: Arial, sans-serif;
}

.tree ul {
    padding-left: 40px;
    position: relative;
}

.tree li {
    list-style-type: none;
    margin: 10px;
    position: relative;
}

.tree li::before, .tree li::after {
    content: '';
    position: absolute;
    left: -20px;
}

.tree li::before {
    border-left: 1px solid #999;
    height: 100%;
    top: 0;
}

.tree li::after {
    border-top: 1px solid #999;
    width: 20px;
    top: 50%;
}

.tree li:last-child::before {
    height: 50%;
}

.tree .node {
    border: 1px solid #999;
    padding: 10px;
    background-color: #f0f0f0;
    display: inline-block;
    border-radius: 5px;
}