body {
        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen,
            Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
        background-color: #fff;
        color: #333;
        padding: 2rem;
        margin: auto;
    }

    h2 {
        margin-top: 0;
    }

    .toolbar {
        margin-bottom: 10px;
    }

    button {
        background-color: transparent;
        border: 1px solid #ccc;
        padding: 0.4rem 0.8rem;
        cursor: pointer;
        font-size: 14px;
        transition: background 0.2s ease;
    }

    button:hover {
        background-color: #eee;
    }

    .node-input {
        display: flex;
        align-items: center;
        margin-top: 5px;
    }

    input[type="text"] {
        width: 200px;
        padding: 5px;
        margin-right: 5px;
    }

    #treeOutput {
        white-space: pre;
        background-color: #f9f9f9;
        padding: 1rem;
        overflow-x: auto;
        margin-top: 1rem;
        font-family: monospace;
        font-size: 14px;
        line-height: 1.6;
    }