/* 讓背景更有層次，不再是死板的灰色 */
body {
    background: radial-gradient(circle, #ffffff 0%, #d7d7d7 100%);
    font-family: 'PingFang TC', 'Microsoft JhengHei', sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

/* 容器改為毛玻璃質感，並增加圓角 */
.container {
    text-align: center;
    background: rgba(255, 255, 255, 0.95);
    padding: 40px;
    border-radius: 24px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.1); /* 更柔和的大陰影 */
}

h1 {
    color: #2c3e50;
    font-weight: 700;
    margin-bottom: 30px;
}

/* 棋盤優化：增加木質感與深度 */
#chess {
    display: block;
    margin: 25px auto;
    background-color: #f3c178; /* 稍微亮一點的木頭色 */
    background-image: linear-gradient(rgba(0,0,0,0.05) 1px, transparent 1px),
                      linear-gradient(90deg, rgba(0,0,0,0.05) 1px, transparent 1px);
    background-size: 30px 30px; /* 模擬格線背景 */
    border: 8px solid #d4a356;
    border-radius: 4px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3), inset 0 0 100px rgba(0,0,0,0.05);
    cursor: crosshair; /* 改為十字準心，更有對弈感 */
}

/* 控制面板排列更整齊 */
.setup-panel {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    margin-bottom: 20px;
}

input, select {
    padding: 12px 15px;
    border: 2px solid #eee;
    border-radius: 10px;
    outline: none;
    transition: all 0.3s;
}

input:focus, select:focus {
    border-color: #4CAF50;
    box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.2);
}

/* 按鈕改為現代風格 */
button {
    padding: 12px 25px;
    background: linear-gradient(135deg, #4CAF50 0%, #2E7D32 100%);
    color: white;
    font-weight: 600;
    letter-spacing: 1px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(76, 175, 80, 0.3);
    transition: all 0.3s ease;
}

button:hover {
    transform: translateY(-2px); /* 滑過時往上飄 */
    box-shadow: 0 6px 20px rgba(76, 175, 80, 0.4);
    filter: brightness(1.1);
}

button:active {
    transform: translateY(1px); /* 點擊時按下去 */
}

/* 針對「重新開始」按鈕給予不同的視覺暗示 */
.controls button {
    background: #fff;
    color: #e74c3c;
    border: 2px solid #e74c3c;
    box-shadow: none;
}

.controls button:hover {
    background: #e74c3c;
    color: #fff;
}