/* 确保 body 和 html 占据全屏 */
        html, body {
            margin: 0;
            padding: 0;
            width: 100%;
            height: 100%;
            overflow: hidden; /* 防止滚动条 */
            background-color: #0d122b; /* 深色背景 */
        }
        canvas {
            display: block; /* 移除 canvas 下方空隙 */
            width: 100%;
            height: 100%;
        }
        /* 控制面板的默认样式 - NEW: 默认隐藏 */
        .content {
            position: fixed;
            bottom: 20px;
            right: 20px;
            padding: 15px;
            background: rgba(10, 15, 40, 0.5); /* 半透明背景 */
            border-radius: 10px;
            box-shadow: 0 0 20px rgba(100, 150, 255, 0.2);
            backdrop-filter: blur(5px); /* 磨砂效果 */
            max-width: 300px;
            z-index: 10; /* 确保在其他元素之上 */
            text-align: center;
            color: #fff; /* 文字颜色 */
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            opacity: 0.9;
            display: none; /* NEW: Default to hidden */
        }
        /* NEW: Display control panel when body has 'show-controls' class */
        body.show-controls .content {
            display: block;
        }

        .content h2 {
            margin-top: 0;
            color: #fff;
            font-size: 1.2em;
        }
        .content p {
            font-size: 0.9em;
            margin-bottom: 10px;
        }
        .content button {
            background-color: #2a6dbd; /* 按钮背景 */
            color: white;
            border: none;
            /* MODIFIED: Fixed padding and width for alignment */
            padding: 8px 10px; /* Adjust padding to fit text and achieve desired height */
            width: 110px; /* Fixed width for alignment */
            margin: 5px;
            border-radius: 5px;
            cursor: pointer;
            transition: background-color 0.3s ease;
            font-size: 0.9em;
            display: inline-block; /* Ensure buttons behave correctly with width */
        }
        .content button:hover {
            background-color: #3f86e3; /* 按钮悬停效果 */
        }
        /* MODIFIED: Add a container for buttons to handle layout */
        .content div {
            display: flex;
            justify-content: center; /* Center button groups */
            flex-wrap: wrap; /* Allow buttons to wrap if needed */
        }



/* 弹窗样式 */
.popup-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7); /* 半透明黑色背景 */
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000; /* 确保在最上层 */
    visibility: hidden; /* 默认隐藏 */
    opacity: 0;
    transition: visibility 0s, opacity 0.3s ease;
}

.popup-overlay.visible {
    visibility: visible;
    opacity: 1;
}

.popup-content {
    background: rgba(10, 15, 40, 0.95); /* 半透明深色背景 */
    color: #e0e0e0;
    padding: 30px 40px;
    border-radius: 15px;
    box-shadow: 0 0 30px rgba(100, 150, 255, 0.5);
    max-width: 600px;
    max-height: 80vh; /* 最大高度，防止内容过长 */
    overflow-y: auto; /* 内容溢出时显示滚动条 */
    position: relative;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    font-size: 1.1em;
    text-align: justify; /* 内容对齐 */
    backdrop-filter: blur(8px); /* 磨砂效果 */
}

.close-button {
    position: absolute;
    top: 15px;
    right: 20px;
    font-size: 30px;
    color: #aaa;
    cursor: pointer;
    transition: color 0.3s ease;
}

.close-button:hover {
    color: #fff;
}

#popupText {
    margin: 0;
    margin-top: 10px; /* 标题与内容间距 */
    white-space: pre-wrap; /* 保留文本中的换行 */
}