body { 
      font-family: Arial, Helvetica, sans-serif; 
      text-align: center; 
      margin: 0; 
      padding: 0; 
      background-color: #2d3250; 
      color: #e0e0e0; 
    } 
 
    #controls { 
      margin: 20px; 
      padding: 15px; 
      background-color: #2b2b2b; 
      border-radius: 10px; 
      display: inline-block; 
      box-shadow: 0 4px 10px rgba(0,0,0,0.4); 
    } 
 
    .divs { 
      display: inline; 
      padding: 0px 30px; 
    } 
 
    input, button, select { 
      margin: 5px; 
      padding: 8px 12px; 
      border: none; 
      border-radius: 6px; 
      font-size: 14px; 
    } 
 
    input, select { 
      background-color: #333; 
      color: #e0e0e0; 
    } 
 
    button { 
      background-color: #444; 
      color: #e0e0e0; 
      cursor: pointer; 
      transition: background-color 0.3s, color 0.3s; 
    } 
 
    button:hover { 
      background-color: #666; 
      color: #ffffff; 
    } 
 
    svg { 
      width: 700px; 
      height: 500px; 
      background-color: #2d3250; 
      margin-top: 20px; 
    } 
 
    .node circle { 
      fill: #424769; 
      stroke: #eeeeee; 
      stroke-width: 3px; 
    } 
 
    .highlight circle { 
      fill: #c0392b !important; 
      stroke: #e0e0e0; 
      stroke-width: 3px; 
    } 
 
    .inserted circle { 
      fill: #2980b9 !important; 
      stroke: #e0e0e0; 
      stroke-width: 3px; 
    } 
 
    #message { 
      margin-top: 15px; 
      font-weight: bold; 
    } 
 
    #message.success { color: #2ecc71; } 
    #message.error { color: #e74c3c; } 
    #message.info { color: #f1c40f; }