* {
     margin: 0;
     padding: 0;
     box-sizing: border-box;
 }

 body {
     font-family: 'Microsoft YaHei', sans-serif;
     background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
     min-height: 100vh;
     display: flex;
     flex-direction: column;
     justify-content: center;
     align-items: center;
     padding: 20px;
     padding-bottom: 60px;
 }

 .game-container {
     background: rgba(255, 255, 255, 0.95);
     border-radius: 20px;
     padding: 30px;
     box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
     width: 100%;
     max-width: 660px;
 }

 h1 {
     text-align: center;
     color: #333;
     margin-bottom: 20px;
     font-size: 2.5em;
     text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
 }

 .info-panel {
     display: flex;
     justify-content: space-between;
     align-items: center;
     margin-bottom: 20px;
     padding: 15px 20px;
     background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
     border-radius: 10px;
 }

 .player-info {
     display: flex;
     align-items: center;
     gap: 10px;
 }

 .stone-preview {
     width: 25px;
     height: 25px;
     border-radius: 50%;
     box-shadow: 2px 2px 5px rgba(0, 0, 0, 0.3);
 }

 .black-stone {
     background: radial-gradient(circle at 30% 30%, #555, #000);
 }

 .white-stone {
     background: radial-gradient(circle at 30% 30%, #fff, #ccc);
     border: 1px solid #999;
 }

 .status {
     font-size: 1.2em;
     font-weight: bold;
     color: #333;
 }

 .board-container {
     position: relative;
     margin: 0 auto;
 }

 #board {
     display: block;
     cursor: pointer;
     border-radius: 10px;
     box-shadow: 0 5px 20px rgba(0, 0, 0, 0.2);
 }

 .bottom-section {
     display: flex;
     justify-content: space-between;
     align-items: center;
     margin-top: 20px;
 }

 .score-board {
     display: flex;
     gap: 20px;
     padding: 10px 20px;
     background: #f5f5f5;
     border-radius: 10px;
 }

 .score-item {
     text-align: center;
 }

 .score-label {
     font-size: 0.85em;
     color: #666;
 }

 .score-value {
     font-size: 1.3em;
     font-weight: bold;
     color: #333;
 }

 .controls {
     display: flex;
     gap: 10px;
 }

 button {
     padding: 10px 20px;
     font-size: 1em;
     border: none;
     border-radius: 20px;
     cursor: pointer;
     transition: all 0.3s ease;
     font-weight: bold;
 }

 .btn-restart {
     background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
     color: white;
 }

 .btn-restart:hover {
     transform: translateY(-2px);
     box-shadow: 0 5px 20px rgba(102, 126, 234, 0.4);
 }

 .btn-undo {
     background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
     color: white;
 }

 .btn-undo:hover {
     transform: translateY(-2px);
     box-shadow: 0 5px 20px rgba(245, 87, 108, 0.4);
 }

 .difficulty {
     display: flex;
     justify-content: center;
     gap: 10px;
     margin-top: 15px;
 }

 .difficulty label {
     padding: 8px 16px;
     background: #e0e0e0;
     border-radius: 20px;
     cursor: pointer;
     transition: all 0.3s ease;
 }

 .difficulty input[type="radio"] {
     display: none;
 }

 .difficulty input[type="radio"]:checked+label {
     background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
     color: white;
 }

 .modal {
     display: none;
     position: fixed;
     top: 0;
     left: 0;
     width: 100%;
     height: 100%;
     background: rgba(0, 0, 0, 0.7);
     justify-content: center;
     align-items: center;
     z-index: 1000;
 }

 .modal.show {
     display: flex;
 }

 .modal-content {
     background: white;
     padding: 40px;
     border-radius: 20px;
     text-align: center;
     animation: popIn 0.3s ease;
 }

 @keyframes popIn {
     from {
         transform: scale(0.5);
         opacity: 0;
     }

     to {
         transform: scale(1);
         opacity: 1;
     }
 }

 .modal h2 {
     font-size: 2em;
     margin-bottom: 20px;
     color: #333;
 }

 .winner-text {
     font-size: 1.5em;
     margin-bottom: 30px;
     color: #666;
 }

 /* 底部备案信息 */
 footer {
     position: fixed;
     bottom: 0;
     left: 0;
     right: 0;
     text-align: center;
     padding: 15px 0;
     background: transparent;
 }

 footer a {
     color: white;
     text-decoration: none;
     font-size: 14px;
 }

 footer a:hover {
     text-decoration: underline;
 }