body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f4f4f4;
}

.container {
    text-align: center;
    width: 90%;
    max-width: 1200px;
}

h1 {
    margin-bottom: 20px;
}

#tree {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
}

.node {
    margin: 10px;
    padding: 20px;
    background: #fff;
    border: 1px solid #ddd;
    border-radius: 5px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.node > .children {
    margin-top: 10px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}