* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  :root {
    --main-bg-color: #0a0a23;
    --section-bg-color: #ffffff;
    --golden-yellow: #feac32;
  }
  
  body {
    background-color: var(--main-bg-color);
  }
  
  .start-screen {
    background-color: var(--section-bg-color);
    width: 100%;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-right: -50%;
    transform: translate(-50%, -50%);
    border-radius: 30px;
    padding: 20px;
    padding-bottom: 5px;
  }
  
  .main-title {
    text-align: center;
  }
  
  .instructions {
    text-align: center;
    font-size: 1.2rem;
    margin: 15px;
    line-height: 2rem;
  }
  
  .btn {
    cursor: pointer;
    width: 100px;
    margin: 10px;
    color: #0a0a23;
    font-size: 18px;
    background-color: var(--golden-yellow);
    background-image: linear-gradient(#fecc4c, #ffac33);
    border-color: var(--golden-yellow);
    border-width: 3px;
  }
  
  .btn:hover {
    background-image: linear-gradient(#ffcc4c, #f89808);
  }
  
  .btn-container {
    display: flex;
    align-items: center;
    justify-content: center;
  }
  
  .checkpoint-screen {
    position: absolute;
    left: 0;
    right: 0;
    margin-left: auto;
    margin-right: auto;
    width: 100%;
    text-align: center;
    background-color: var(--section-bg-color);
    border-radius: 20px;
    padding: 10px;
    display: none;
  }
  
  #canvas {
    display: none;
  }
  
  @media (min-width: 768px) {
    .start-screen {
      width: 60%;
      max-width: 700px;
    }
  
    .checkpoint-screen {
      max-width: 300px;
    }
  }