/* Grid container for the board */
      #game-board {
        display: grid;
        grid-template-columns: repeat(9, 1fr);
        gap: 2px;
        width: 95%;
        max-width: 600px;
        border: 3px solid #6366f1;
        border-radius: 8px;
        box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
        background-color: #6366f1;
      }

      /* Tile styling */
      .tile {
        aspect-ratio: 1 / 1;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 1.2rem;
        font-weight: 700;
        background-color: white;
        border-radius: 4px;
        cursor: pointer;
        transition: all 0.2s ease-out;
        color: #1f2937;
      }

      /* Empty tile */
      .tile.empty {
        background-color: #e5e7eb;
        cursor: default;
        color: transparent;
      }

      /* selectedCell tile */
      .tile.selectedCell {
        background-color: #6366f1; /* Indigo */
        color: white;
        transform: scale(1.05);
        box-shadow: 0 0 0 3px #10b981; /* Green glow */
      }

      /* Message Box */
      #message-box {
        position: fixed;
        top: 10%;
        left: 50%;
        transform: translateX(-50%);
        padding: 1rem 2rem;
        background-color: #ef4444;
        color: white;
        border-radius: 8px;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
        opacity: 0;
        transition: opacity 0.5s;
        z-index: 1000;
        pointer-events: none;
      }

      .show-msg {
        opacity: 1 !important;
      }