/* Element Name Selector */
body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    background-color: #6da3d6;
    color: #3e3333;
    padding: 20px;
}

/* ID Selector */
#main-header {
    text-align: center;
    color: #050f1a;
    border-bottom: 2px solid #01172d;
    margin-bottom: 30px;
}

/* Class Name Selector */
.content-box {
    background-color: #eff1ff;
    padding: 15px;
    margin-bottom: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.tree-diagram {
    display: block;
    margin: 20px auto;
    max-width: 100%;
    height: auto;
    border: 1px solid #ddd;
}