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

body {
    font-family: 'Segoe UI', 'Microsoft YaHei', sans-serif;
    background-color: #f5f0eb;
    background-image: url('images/background.png');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    min-height: 100vh;
    padding: 15px 30px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    max-width: 1300px;
    width: 100%;
    background-color: rgba(255, 248, 240, 0.92);
    border-radius: 24px;
    padding: 18px 35px 14px 35px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.12);
    border: 1px solid rgba(255, 255, 255, 0.4);
    max-height: calc(100vh - 30px);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.nav-bar {
    list-style: none;
    margin-bottom: 10px;
    padding-bottom: 10px;
    border-bottom: 2px solid rgba(181, 101, 29, 0.2);
    overflow: hidden;
    flex-shrink: 0;
}

.nav-bar li {
    float: left;
    margin-right: 24px;
}

.nav-bar li:last-child {
    margin-right: 0;
}

.nav-bar li a {
    display: block;
    text-decoration: none;
    color: #3d2c1e;
    font-weight: 600;
    font-size: 16px;
    letter-spacing: 1px;
    padding: 3px 0;
    transition: color 0.2s, border-bottom 0.2s;
    border-bottom: 2px solid transparent;
}

.nav-bar li a:hover {
    color: #b5651d;
    border-bottom-color: #b5651d;
}

.content {
    display: flex;
    flex: 1;
    min-height: 0;
    gap: 20px;
    height: 100%;
}

.left-panel {
    flex: 0 0 55%;
    max-height: 100%;
    min-height: 0;
    overflow-y: auto;
    padding-right: 20px;
    border-right: 1px solid rgba(181, 101, 29, 0.12);
}

.left-panel p {
    font-size: 15px;
    color: #4a3a2a;
    line-height: 1.8;
    margin-bottom: 8px;
    text-indent: 2em;
}

.left-panel h2 {
    font-size: 26px;
    color: #3d2c1e;
    margin-bottom: 4px;
    letter-spacing: 2px;
}

.left-panel .intro-text {
    font-size: 15px;
    color: #5a4a3a;
    line-height: 1.7;
    margin-bottom: 12px;
}

.left-panel h3 {
    font-size: 18px;
    color: #4a3a2a;
    margin: 14px 0 8px 0;
    border-left: 4px solid #b5651d;
    padding-left: 12px;
}

.left-panel ol {
    padding-left: 22px;
    font-size: 14px;
    color: #3d2c1e;
    line-height: 1.8;
}

.left-panel ol li {
    margin-bottom: 1px;
}

.right-panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding-left: 6px;
}

.board-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 2px;
    flex-shrink: 0;
}

.board-header h3 {
    font-size: 20px;
    color: #3d2c1e;
    margin: 0;
}

.board-header .init-btn {
    padding: 6px 20px;
    border: none;
    border-radius: 30px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    background-color: #4a6a5c;
    color: #f5ede4;
    transition: background-color 0.25s, transform 0.15s;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.board-header .init-btn:hover {
    background-color: #5f7f6f;
    transform: translateY(-2px);
}

.board-header .init-btn:active {
    transform: scale(0.97);
}

#board-container {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 0;
}

#board-container table {
    border-collapse: collapse;
    border: 4px solid #4a3a2b;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 6px 24px rgba(0, 0, 0, 0.15);
}

#board-container td {
    width: 70px;
    height: 70px;
    text-align: center;
    vertical-align: middle;
    cursor: pointer;
    border: 2px solid #4a3a2b;
    transition: transform 0.12s, box-shadow 0.12s;
    position: relative;
}

#board-container td img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
    padding: 11px;
    box-sizing: border-box;
}

.footer {
    text-align: center;
    font-size: 12px;
    color: #b0a090;
    margin-top: 8px;
    padding-top: 10px;
    border-top: 1px solid rgba(181, 101, 29, 0.12);
    letter-spacing: 1px;
    flex-shrink: 0;
}