/* body full-screen, centered column */
body {
    margin: 0;
    min-height: 100vh;
    display: flex;
    background: #111;
    color: #eee;
    font-family: system-ui, sans-serif;
    align-items: center;
    justify-content: center;
  }
  
  /* container centers content with max width */
  .container {
    text-align: center;
    padding: 2rem;
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
  }
  
  h1 {
    margin: 0 0 1rem;
    font-size: 2rem;
  }
  
  /* responsive canvas size, centered */
  #board {
    border: 3px solid #444;
    background: #222;
    image-rendering: pixelated;
    width: 80vw;
    max-width: 640px;
    height: auto;
    display: block;
    margin: 0 auto;
  }
  
  #progress {
    margin: .5rem 0 1rem;
    font-size: 1rem;
  }
  
  button#revealBtn {
    font-size: 1.1rem;
    padding: .6rem 1.4rem;
    border: none;
    border-radius: 6px;
    background: #28a;
    color: #fff;
    cursor: pointer;
    transition: background .2s ease;
  }
  
  button#revealBtn:disabled {
    background: #444;
    cursor: not-allowed;
    opacity: .6;
  }
  
  button#revealBtn:not(:disabled):hover {
    background: #3af;
  }
  
  .hint {
    margin-top: 1rem;
    font-size: .8rem;
    color: #888;
  }