body {
    display: flex;
    flex-direction: column;
    align-items: center;
    font-family: Arial, sans-serif;
  }
  
  #new-grid-btn {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
  }
  
  #container {
    margin-top: 20px;
    display: flex;
    flex-wrap: wrap;
    width: 960px;
    height: 960px;
    border: 2px solid black;
    background-color: #f0f0f0;
  }
  
  .square {
    border: 1px solid #bbb;
    box-sizing: border-box;
    flex-shrink: 0;
  }