.grid {
    display: grid;
    gap: 14px;
  }
  
  /* Desktop */
  @media (min-width: 768px) {
    .grid {
      grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    }
  }
  
  /* Mobile */
  @media (max-width: 767px) {
    .grid {
      grid-template-columns: 1fr;
      padding: 0 16px;
    }
  }
  
  .card {
    width: 100%;
    max-width: 360px;
    height: 260px;
    margin: 0 auto;
    perspective: 1000px;
  }
  
  .inner {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: 0.6s;
  }
  
  .inner.flip {
    transform: rotateY(180deg);
  }
  
  .front, .back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
  
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
  }
  
  .front {
    background: #fff;
    font-size: 60px;
    font-weight: normal;
  }
  
  .back {
    background: #fff; /* cùng màu front */
    transform: rotateY(180deg);
    padding: 16px;
    gap: 10px;
    text-align: center;
  }
  
  .meaning {
    font-size: 22px;
    font-weight: bold;
  }
  
  .vi, .en {
    margin: 2px 0;
  }
  
  .pinyin {
    font-size: 14px;
    font-style: italic;
    color: #555;
  }
  
  .back img {
    width: 120px;
    height: 120px;
    object-fit: contain;
    margin-top: 10px;
  }