/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 三体风格设计系统 - 英语学习游戏主题 */
    /* 主色调：三体青色 - 代表科技与未来 */
    --primary-color: #00ffff;      /* 三体青色 */
    --primary-dark: #00cccc;       /* 深青色 */
    --primary-light: rgba(0, 255, 255, 0.3); /* 浅青色 */
    --primary-50: rgba(0, 255, 255, 0.1);    /* 超浅青色 */
    
    /* 次要色：三体品红 - 代表神秘与力量 */
    --secondary-color: #ff00ff;    /* 三体品红 */
    --secondary-dark: #cc00cc;     /* 深品红 */
    --secondary-light: rgba(255, 0, 255, 0.3); /* 浅品红 */
    
    /* 强调色：成就金 - 奖励和成就 */
    --accent-color: #FBBF24;       /* 金色 */
    --accent-dark: #D97706;        /* 深金色 */
    --accent-light: #FEF3C7;       /* 浅金色 */
    
    /* 紫色系：三体紫 - 创意和想象 */
    --purple-color: #8B5CF6;       /* 紫色 */
    --purple-dark: #7C3AED;        /* 深紫色 */
    --purple-light: #EDE9FE;       /* 浅紫色 */
    
    /* 绿色系：成长绿 - 学习和成长 */
    --success-color: #10B981;      /* 成功绿色 */
    --success-dark: #059669;       /* 深绿色 */
    --success-light: #D1FAE5;      /* 浅绿色 */
    
    /* 红色系：警示红 */
    --error-color: #EF4444;        /* 错误红色 */
    --error-dark: #DC2626;         /* 深红色 */
    --error-light: #FEE2E2;        /* 浅红色 */
    
    /* 警告色 */
    --warning-color: #F59E0B;      /* 警告橙色 */
    --warning-dark: #D97706;       /* 深橙色 */
    --warning-light: #FEF3C7;      /* 浅橙色 */
    
    /* 三体风格中性色 */
    --background-color: #0a0a1a;   /* 三体深色背景 */
    --text-color: #ffffff;         /* 三体白色文字 - 更亮 */
    --light-text: #c0c0e0;         /* 三体次要文字 - 更亮 */
    --muted-text: #a0a0c0;         /* 三体更浅文字 - 更亮 */
    --border-color: rgba(0, 255, 255, 0.25); /* 三体边框色 - 更明显 */
    --border-light: rgba(0, 255, 255, 0.15); /* 三体极浅边框色 - 更明显 */
    
    /* 三体风格阴影系统 */
    --shadow-sm: 0 0 5px rgba(0, 255, 255, 0.1);
    --shadow: 0 0 15px rgba(0, 255, 255, 0.2);
    --shadow-md: 0 0 25px rgba(0, 255, 255, 0.3);
    --shadow-lg: 0 0 35px rgba(0, 255, 255, 0.4);
    --shadow-xl: 0 0 50px rgba(0, 255, 255, 0.5);
    --shadow-hover: 0 0 30px rgba(0, 255, 255, 0.4);
    
    /* 圆角系统 */
    --border-radius-sm: 8px;
    --border-radius: 12px;
    --border-radius-md: 16px;
    --border-radius-lg: 24px;
    --border-radius-xl: 32px;
    --border-radius-full: 9999px;
    
    /* 过渡动画 */
    --transition-fast: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-bounce: all 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
    
    /* 字体变量 */
    --font-display: 'Segoe UI', 'Microsoft YaHei', sans-serif;
    --font-body: 'Segoe UI', 'Microsoft YaHei', sans-serif;
    --font-mono: 'Fira Code', monospace;
    
    /* 间距系统 */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    --space-4xl: 6rem;
    
    /* 三体风格游戏特定主题色 */
    /* 大富翁主题 - 三体青色 */
    --monopoly-primary: #00cccc;
    --monopoly-secondary: #00ffff;
    --monopoly-accent: #00e6e6;
    --monopoly-bg: linear-gradient(135deg, #0a0a1a 0%, #1a1a3a 50%, #0a0a1a 100%);
    
    /* 单词配对主题 - 三体品红 */
    --wordmatch-primary: #cc00cc;
    --wordmatch-secondary: #ff00ff;
    --wordmatch-accent: #e600e6;
    --wordmatch-bg: linear-gradient(135deg, #0a0a1a 0%, #1a0a1a 50%, #0a0a1a 100%);
    
    /* 单词大爆炸主题 - 三体金色 */
    --wordblast-primary: #D97706;
    --wordblast-secondary: #FBBF24;
    --wordblast-accent: #F59E0B;
    --wordblast-bg: linear-gradient(135deg, #0a0a1a 0%, #1a1a0a 50%, #0a0a1a 100%);
}

body {
    font-family: var(--font-body);
    background: var(--background-color);
    background-size: 400% 400%;
    animation: gradient-shift 15s ease infinite;
    color: var(--text-color);
    min-height: 100vh;
    overflow: hidden;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 80%, rgba(0, 255, 255, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255, 0, 255, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(0, 255, 255, 0.05) 0%, transparent 70%);
    pointer-events: none;
    z-index: 0;
}

@keyframes gradient-shift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* 三体风格粒子背景 */
body::after {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        radial-gradient(circle at 10% 20%, rgba(0, 255, 255, 0.15) 1px, transparent 1px),
        radial-gradient(circle at 90% 80%, rgba(255, 0, 255, 0.15) 1px, transparent 1px),
        radial-gradient(circle at 50% 50%, rgba(0, 255, 255, 0.1) 1px, transparent 1px);
    background-size: 100px 100px, 150px 150px, 200px 200px;
    pointer-events: none;
    z-index: 0;
    animation: float-particles 20s linear infinite;
}

@keyframes float-particles {
    0% { transform: translateY(0) rotate(0deg); }
    100% { transform: translateY(-100px) rotate(5deg); }
}

/* 游戏容器 */
#game-container {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    z-index: 1;
}

/* 三体风格加载屏幕 */
#loading-screen {
    text-align: center;
    color: var(--text-color);
    background: var(--background-color);
    border: 1px solid var(--border-color);
    padding: 40px;
    border-radius: var(--border-radius);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

#loading-screen::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(0, 255, 255, 0.1) 0%, transparent 70%);
    animation: loading-glow 3s ease-in-out infinite;
}

#loading-screen h1 {
    font-family: var(--font-display);
    font-size: 3rem;
    margin-bottom: var(--space-md);
    text-shadow: 0 0 20px rgba(0, 255, 255, 0.5);
    position: relative;
    z-index: 1;
    letter-spacing: 2px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.loading-subtitle {
    font-size: 1.2rem;
    color: var(--light-text);
    margin-bottom: var(--space-xl);
    position: relative;
    z-index: 1;
    font-weight: 600;
}

.loading-text {
    font-size: 1rem;
    color: rgba(255, 255, 255, 0.8);
    position: relative;
    z-index: 1;
    margin-top: var(--space-md);
}

.menu-subtitle {
    font-size: 1.3rem;
    color: var(--light-text);
    text-align: center;
    margin-bottom: var(--space-xl);
    font-weight: 600;
}

.loading-bar {
    width: 350px;
    height: 24px;
    background: rgba(0, 255, 255, 0.1);
    border-radius: 12px;
    margin: 30px auto;
    overflow: hidden;
    position: relative;
    z-index: 1;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2);
    border: 1px solid rgba(0, 255, 255, 0.2);
}

.loading-progress {
    width: 0%;
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 12px;
    transition: width 0.3s ease;
    animation: loading 2s ease-in-out infinite;
    box-shadow: 0 0 10px rgba(0, 255, 255, 0.3);
}

@keyframes loading {
    0% { width: 0%; }
    50% { width: 75%; }
    100% { width: 100%; }
}

@keyframes loading-glow {
    0%, 100% { transform: rotate(0deg); }
    50% { transform: rotate(180deg); }
}

/* UI覆盖层 */
#ui-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 100;
    pointer-events: none;
}

/* 三体风格UI屏幕 */
.ui-screen {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--background-color);
    padding: var(--space-3xl);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-xl);
    pointer-events: all;
    max-width: 1200px;
    width: 94%;
    max-height: 90vh;
    overflow-y: auto;
    backdrop-filter: blur(25px);
    border: 1px solid var(--border-color);
    animation: screen-enter 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
    z-index: 10;
}

@keyframes screen-enter {
    from {
        opacity: 0;
        transform: translate(-50%, -50%) scale(0.85) translateY(30px);
        filter: blur(10px);
    }
    to {
        opacity: 1;
        transform: translate(-50%, -50%) scale(1) translateY(0);
        filter: blur(0px);
    }
}

.ui-screen h1, .ui-screen h2 {
    color: var(--primary-color);
    margin-bottom: var(--space-lg);
    text-align: center;
    font-family: var(--font-display);
    letter-spacing: 1px;
    text-shadow: 0 0 10px rgba(0, 255, 255, 0.3);
}

.ui-screen h1 {
    font-size: 2.8rem;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: none;
    margin-bottom: var(--space-xl);
}

.ui-screen h2 {
    font-size: 2rem;
    color: var(--primary-color);
    position: relative;
}

.ui-screen h2::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 2px;
}

.hidden {
    display: none !important;
}

/* 菜单按钮 */
.menu-buttons {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-xl);
    margin: var(--space-2xl) 0;
}

.menu-btn {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--background-color);
    border: none;
    border-left: 5px solid rgba(0, 255, 255, 0.6);
    padding: var(--space-xl) var(--space-2xl);
    border-radius: var(--border-radius-md);
    font-family: var(--font-body);
    font-size: 1.4rem;
    font-weight: 800;
    cursor: pointer;
    transition: var(--transition-bounce);
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
    text-transform: capitalize;
    letter-spacing: 0.5px;
    transform: perspective(1000px) rotateX(0deg);
    transform-origin: center center;
    width: 100%;
    max-width: 420px;
    text-align: center;
}

.menu-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: 0.6s;
}

.menu-btn:hover {
    transform: translateY(-6px) scale(1.03);
    box-shadow: var(--shadow-lg);
    border-left-width: 6px;
    border-left-color: var(--primary-color);
}

.menu-btn:hover::before {
    left: 100%;
}

.menu-btn:active {
    transform: translateY(-2px) scale(0.98);
    box-shadow: var(--shadow);
}

/* 3D悬停效果 */
.menu-btn:nth-child(1):hover {
    transform: perspective(1000px) rotateX(-5deg) translateY(-6px) scale(1.03);
}

.menu-btn:nth-child(2):hover {
    transform: perspective(1000px) rotateX(-5deg) translateY(-6px) scale(1.03);
}

.menu-btn:nth-child(3):hover {
    transform: perspective(1000px) rotateY(5deg) translateY(-6px) scale(1.03);
}

.menu-btn:nth-child(4):hover {
    transform: perspective(1000px) rotateX(5deg) translateY(-6px) scale(1.03);
}

/* 菜单按钮颜色 - 每个游戏独特的主题 */
.menu-btn:nth-child(1) { /* 记单词 */
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-left-color: var(--primary-color);
    font-size: 1.4rem;
    padding: var(--space-xl) var(--space-2xl);
    width: 100%;
    max-width: 420px;
    box-shadow: 0 10px 25px -5px rgba(0, 255, 255, 0.4);
    position: relative;
    overflow: hidden;
}

.menu-btn:nth-child(1)::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 80%, rgba(255, 255, 255, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255, 255, 255, 0.08) 0%, transparent 50%);
    opacity: 0.5;
    pointer-events: none;
}

.menu-btn:nth-child(1):hover {
    box-shadow: 0 15px 35px -5px rgba(0, 255, 255, 0.5);
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-color));
}

.menu-btn:nth-child(1):hover::after {
    opacity: 0.8;
}

.menu-btn:nth-child(2) { /* 大富翁 */
    background: linear-gradient(135deg, var(--monopoly-primary), var(--monopoly-secondary));
    border-left-color: var(--monopoly-accent);
    font-size: 1.4rem;
    padding: var(--space-xl) var(--space-2xl);
    width: 100%;
    max-width: 420px;
    box-shadow: 0 10px 25px -5px rgba(5, 150, 105, 0.4);
    position: relative;
    overflow: hidden;
}

.menu-btn:nth-child(2)::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(45deg, rgba(255, 255, 255, 0.1) 25%, transparent 25%),
        linear-gradient(-45deg, rgba(255, 255, 255, 0.1) 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, rgba(255, 255, 255, 0.1) 75%),
        linear-gradient(-45deg, transparent 75%, rgba(255, 255, 255, 0.1) 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
    opacity: 0.3;
    pointer-events: none;
}

.menu-btn:nth-child(2):hover {
    box-shadow: 0 15px 35px -5px rgba(5, 150, 105, 0.5);
    background: linear-gradient(135deg, var(--monopoly-secondary), var(--monopoly-primary));
}

.menu-btn:nth-child(2):hover::after {
    opacity: 0.5;
}

.menu-btn:nth-child(3) { /* 单词匹配 */
    background: linear-gradient(135deg, var(--wordmatch-primary), var(--wordmatch-secondary));
    border-left-color: var(--wordmatch-accent);
    font-size: 1.4rem;
    padding: var(--space-xl) var(--space-2xl);
    width: 100%;
    max-width: 420px;
    box-shadow: 0 10px 25px -5px rgba(139, 92, 246, 0.4);
    position: relative;
    overflow: hidden;
}

.menu-btn:nth-child(3)::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 30px;
    height: 30px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 4px;
    transform: translate(-50%, -50%) rotate(45deg);
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
}

.menu-btn:nth-child(3):hover::after {
    opacity: 1;
    transform: translate(-50%, -50%) rotate(45deg) scale(1.5);
    background: rgba(255, 255, 255, 0.3);
}

.menu-btn:nth-child(3):hover {
    box-shadow: 0 15px 35px -5px rgba(139, 92, 246, 0.5);
    background: linear-gradient(135deg, var(--wordmatch-secondary), var(--wordmatch-primary));
}

.menu-btn:nth-child(4) { /* 单词爆炸 */
    background: linear-gradient(135deg, var(--wordblast-primary), var(--wordblast-secondary));
    border-left-color: var(--wordblast-accent);
    font-size: 1.4rem;
    padding: var(--space-xl) var(--space-2xl);
    width: 100%;
    max-width: 420px;
    box-shadow: 0 10px 25px -5px rgba(239, 68, 68, 0.4);
    position: relative;
    overflow: hidden;
}

.menu-btn:nth-child(4)::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: radial-gradient(circle, rgba(255, 209, 102, 0.6) 0%, rgba(239, 68, 68, 0.3) 50%, transparent 70%);
    border-radius: 50%;
    transform: translate(-50%, -50%);
    transition: all 0.4s ease;
    pointer-events: none;
    opacity: 0;
}

.menu-btn:nth-child(4):hover::before {
    width: 300px;
    height: 300px;
    opacity: 1;
}

.menu-btn:nth-child(4):hover {
    box-shadow: 0 15px 35px -5px rgba(239, 68, 68, 0.5), 0 0 30px rgba(255, 209, 102, 0.3);
    background: linear-gradient(135deg, var(--wordblast-secondary), var(--wordblast-primary));
}

/* 三体风格玩家信息 */
.player-info {
    display: flex;
    align-items: center;
    background: var(--background-color);
    padding: var(--space-lg);
    border-radius: var(--border-radius);
    margin-top: var(--space-xl);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
}

.player-info::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color), var(--accent-color));
}

.player-avatar {
    font-size: 4rem;
    margin-right: var(--space-lg);
    text-shadow: 0 0 20px rgba(0, 255, 255, 0.5);
    background: linear-gradient(135deg, rgba(0, 255, 255, 0.1), rgba(255, 0, 255, 0.1));
    width: 80px;
    height: 80px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    box-shadow: var(--shadow);
    border: 3px solid var(--primary-color);
}

.player-stats {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.player-name {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-shadow: 0 0 10px rgba(0, 255, 255, 0.5);
}

.player-level {
    color: var(--secondary-color);
    font-weight: 700;
    font-size: 1.1rem;
    text-shadow: 0 0 10px rgba(255, 0, 255, 0.3);
}

.player-exp {
    color: var(--light-text);
    font-size: 0.95rem;
}

/* 年级选择 */
.grade-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: var(--space-lg);
    margin-top: var(--space-xl);
}

.grade-btn {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--background-color);
    border: 1px solid rgba(0, 255, 255, 0.3);
    padding: var(--space-xl);
    border-radius: var(--border-radius);
    font-family: var(--font-body);
    font-size: 1.2rem;
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
}

.grade-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: 0.6s;
}

.grade-btn:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: var(--shadow-hover);
}

.grade-btn:hover::before {
    left: 100%;
}



/* 三体风格游戏界面 */
#game-screen {
    padding: 0;
    background: var(--background-color);
    max-width: 100%;
    width: 100%;
    height: 100%;
    max-height: 100%;
    border-radius: 0;
    backdrop-filter: blur(10px);
    display: flex;
    flex-direction: column;
}

.game-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-sm) var(--space-md);
    background: rgba(10, 10, 26, 0.9);
    color: var(--text-color);
    backdrop-filter: blur(5px);
    border-bottom: 1px solid var(--border-color);
}

.back-btn {
    background: rgba(0, 255, 255, 0.1);
    color: var(--primary-color);
    border: 1px solid rgba(0, 255, 255, 0.3);
    padding: var(--space-sm) var(--space-md);
    border-radius: 25px;
    cursor: pointer;
    transition: var(--transition);
    font-family: var(--font-body);
    font-weight: 600;
}

.back-btn:hover {
    background: rgba(0, 255, 255, 0.2);
    transform: translateY(-1px);
    box-shadow: 0 0 10px rgba(0, 255, 255, 0.3);
}

.game-title {
    font-family: var(--font-display);
    font-size: 1.6rem;
    font-weight: 700;
    letter-spacing: 1px;
    color: var(--primary-color);
    text-shadow: 0 0 10px rgba(0, 255, 255, 0.3);
}

.game-score {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--accent-color);
    background: rgba(251, 191, 36, 0.1);
    padding: var(--space-sm) var(--space-md);
    border-radius: 20px;
    border: 1px solid rgba(251, 191, 36, 0.3);
    text-shadow: 0 0 10px rgba(251, 191, 36, 0.5);
}

#game-canvas-container {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0;
    min-height: 0;
    position: relative;
    overflow: hidden;
}

/* 音效切换按钮 */
.sound-toggle-btn {
    position: absolute;
    top: var(--space-lg);
    left: var(--space-lg);
    width: 44px;
    height: 44px;
    border: none;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(10px);
    font-size: 1.4rem;
    cursor: pointer;
    transition: var(--transition);
    z-index: 10;
}

.sound-toggle-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.1);
}

/* 语言切换按钮 */
.lang-toggle-wrap {
    position: absolute;
    top: var(--space-lg);
    right: var(--space-lg);
    display: flex;
    align-items: center;
    gap: 8px;
    z-index: 10;
}

.lang-label {
    font-size: 12px;
    font-weight: 700;
    color: rgba(255, 255, 255, 0.9);
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
    letter-spacing: 0.5px;
    user-select: none;
}

.lang-switch {
    position: relative;
    display: inline-block;
    width: 48px;
    height: 26px;
}

.lang-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.lang-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(255, 255, 255, 0.3);
    transition: 0.3s;
    border-radius: 26px;
    backdrop-filter: blur(4px);
    border: 2px solid rgba(255, 255, 255, 0.4);
}

.lang-slider:before {
    position: absolute;
    content: "中";
    height: 20px;
    width: 20px;
    left: 2px;
    bottom: 1px;
    background-color: white;
    transition: 0.3s;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 10px;
    font-weight: 800;
    color: var(--primary-color);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.lang-switch input:checked + .lang-slider {
    background-color: rgba(255, 255, 255, 0.5);
}

.lang-switch input:checked + .lang-slider:before {
    transform: translateX(22px);
    content: "EN";
    color: #2E7D32;
}

.lang-switch input:focus + .lang-slider {
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.3);
}

.lang-slider:hover {
    background-color: rgba(255, 255, 255, 0.45);
}

/* 三体风格成就界面 */
.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--space-lg);
    margin: var(--space-xl) 0;
}

.achievement {
    background: var(--background-color);
    padding: var(--space-xl);
    border-radius: var(--border-radius);
    text-align: center;
    border: 1px solid var(--border-color);
    transition: var(--transition);
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
}

.achievement::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-color), var(--secondary-color));
}

.achievement.unlocked {
    background: linear-gradient(135deg, var(--success-color), #2F855A);
    border-color: var(--success-color);
    color: white;
    transform: scale(1.02);
    box-shadow: 0 10px 15px -3px rgba(72, 187, 120, 0.3);
}

.achievement.unlocked::before {
    background: linear-gradient(90deg, #FFD166, #FF6B6B);
}

.achievement.locked {
    opacity: 0.7;
    filter: grayscale(40%);
    transform: scale(0.98);
}

.achievement-icon {
    font-size: 3rem;
    margin-bottom: var(--space-md);
    text-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.achievement-name {
    font-family: var(--font-display);
    font-weight: 700;
    margin-bottom: var(--space-sm);
    font-size: 1.2rem;
}

.achievement-desc {
    font-size: 0.95rem;
    color: var(--light-text);
}

.achievement.unlocked .achievement-desc {
    color: rgba(255, 255, 255, 0.9);
}

/* 三体风格模态框 */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 10, 26, 0.9);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    pointer-events: all;
    backdrop-filter: blur(8px);
    animation: modal-fade-in 0.3s ease;
}

@keyframes modal-fade-in {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal-content {
    background: var(--background-color);
    padding: var(--space-2xl);
    border-radius: var(--border-radius);
    max-width: 550px;
    width: 92%;
    position: relative;
    box-shadow: var(--shadow-xl);
    animation: modal-slide-in 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border: 1px solid var(--border-color);
    color: var(--text-color);
}

@keyframes modal-slide-in {
    from {
        opacity: 0;
        transform: translateY(20px) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.close-modal {
    position: absolute;
    top: var(--space-lg);
    right: var(--space-lg);
    font-size: 2rem;
    cursor: pointer;
    color: var(--light-text);
    transition: var(--transition);
    background: none;
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.close-modal:hover {
    color: var(--primary-color);
    background: rgba(0, 255, 255, 0.1);
}

/* 三体风格单词详情 */
.word-detail {
    text-align: center;
    padding: var(--space-md) 0;
}

.word-text {
    font-family: var(--font-display);
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: var(--space-sm);
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: none;
    filter: drop-shadow(0 0 10px rgba(0, 255, 255, 0.5));
}

.word-phonetic {
    font-size: 1.4rem;
    color: var(--light-text);
    margin-bottom: var(--space-lg);
    font-style: italic;
    font-family: var(--font-mono);
}

.word-meaning {
    font-size: 1.6rem;
    color: var(--text-color);
    margin-bottom: var(--space-xl);
    font-weight: 700;
}

.word-example {
    background: rgba(0, 255, 255, 0.05);
    padding: var(--space-lg);
    border-radius: 12px;
    margin-bottom: var(--space-xl);
    font-style: italic;
    color: var(--light-text);
    border-left: 4px solid var(--primary-color);
    text-align: left;
    font-size: 1.1rem;
    line-height: 1.6;
}

.word-audio {
    margin-bottom: var(--space-xl);
}

.audio-btn {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--background-color);
    border: none;
    padding: var(--space-md) var(--space-xl);
    border-radius: 50px;
    font-family: var(--font-body);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.audio-btn:hover {
    transform: scale(1.05) translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.word-progress {
    margin-top: var(--space-xl);
}

.progress-bar {
    height: 12px;
    background: rgba(0, 255, 255, 0.1);
    border-radius: 6px;
    overflow: hidden;
    margin-bottom: var(--space-md);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2);
    border: 1px solid rgba(0, 255, 255, 0.1);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 6px;
    transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 0 10px rgba(0, 255, 255, 0.3);
}

/* 三体风格游戏特定样式 */
.game-controls {
    display: flex;
    justify-content: center;
    gap: var(--space-md);
    padding: var(--space-md);
    background: rgba(10, 10, 26, 0.8);
    backdrop-filter: blur(5px);
    border-top: 1px solid var(--border-color);
}

.game-control-btn {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--background-color);
    border: none;
    padding: var(--space-md) var(--space-xl);
    border-radius: 25px;
    font-family: var(--font-body);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.game-control-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.game-control-btn.secondary {
    background: rgba(0, 255, 255, 0.1);
    color: var(--primary-color);
    border: 1px solid rgba(0, 255, 255, 0.3);
}

/* 动画效果 */
@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-30px); }
    60% { transform: translateY(-15px); }
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

@keyframes shimmer {
    0% { background-position: -200px 0; }
    100% { background-position: 200px 0; }
}

.pulse {
    animation: pulse 2s infinite;
}

.shake {
    animation: shake 0.5s;
}

.bounce {
    animation: bounce 1s;
}

.float {
    animation: float 3s ease-in-out infinite;
}

/* 交互状态 */
.menu-btn:focus,
.grade-btn:focus {
    outline: none;
    box-shadow: 0 0 0 4px rgba(0, 255, 255, 0.3);
}

.menu-btn:disabled,
.grade-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
}

/* 工具提示 */
[title] {
    position: relative;
}

[title]:hover::after {
    opacity: 1;
    visibility: visible;
    bottom: calc(100% + 8px);
}

/* 加载状态 */
.loading-spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 20px auto;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* 特色动画和微交互 */
@keyframes gradient-shift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

@keyframes text-glow {
    0%, 100% { text-shadow: 0 0 10px rgba(0, 255, 255, 0.5); }
    50% { text-shadow: 0 0 20px rgba(0, 255, 255, 0.8), 0 0 30px rgba(255, 0, 255, 0.6); }
}

@keyframes card-flip {
    0% { transform: perspective(1000px) rotateY(0deg); }
    100% { transform: perspective(1000px) rotateY(180deg); }
}

@keyframes success-pop {
    0% { transform: scale(0.8); opacity: 0; }
    50% { transform: scale(1.1); }
    100% { transform: scale(1); opacity: 1; }
}

.gradient-animate {
    background-size: 200% 200%;
    animation: gradient-shift 4s ease infinite;
}

.text-glow {
    animation: text-glow 2s ease-in-out infinite;
}

.card-flip {
    animation: card-flip 0.6s ease-in-out;
}

.success-pop {
    animation: success-pop 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 悬停效果增强 */
.menu-btn:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: var(--shadow-hover);
}

.menu-btn:active {
    transform: translateY(-2px) scale(0.98);
}

/* 焦点样式 */
:focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
}

/* 三体风格选择文本样式 */
::selection {
    background: var(--primary-color);
    color: var(--background-color);
}

/* 三体风格滚动条样式 */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--background-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: rgba(0, 255, 255, 0.3);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}

/* ===== 英语排行榜弹窗样式 ===== */
.english-lb-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(10, 10, 26, 0.92);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2000;
    opacity: 0;
    transition: opacity 0.3s ease;
    backdrop-filter: blur(8px);
}

.english-lb-modal.active {
    opacity: 1;
}

.english-lb-box {
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    max-width: 800px;
    width: 94%;
    max-height: 85vh;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-xl), 0 0 60px rgba(0, 255, 255, 0.15);
    animation: modal-slide-in 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
    overflow: hidden;
}

.english-lb-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-lg) var(--space-xl);
    border-bottom: 1px solid var(--border-color);
    background: rgba(0, 255, 255, 0.03);
}

.english-lb-title {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin: 0;
}

.english-lb-close {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.15);
    color: var(--light-text);
    font-size: 1.6rem;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    line-height: 1;
}

.english-lb-close:hover {
    background: rgba(239, 68, 68, 0.2);
    border-color: rgba(239, 68, 68, 0.5);
    color: var(--error-color);
    box-shadow: 0 0 10px rgba(239, 68, 68, 0.3);
}

.english-lb-tabs {
    display: flex;
    gap: var(--space-xs);
    padding: var(--space-md) var(--space-xl);
    border-bottom: 1px solid var(--border-light);
    background: rgba(0, 0, 0, 0.2);
    overflow-x: auto;
}

.english-lb-tab {
    background: rgba(0, 255, 255, 0.06);
    border: 1px solid rgba(0, 255, 255, 0.15);
    color: var(--light-text);
    padding: var(--space-sm) var(--space-lg);
    border-radius: var(--border-radius-full);
    font-family: var(--font-body);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
    flex-shrink: 0;
}

.english-lb-tab:hover {
    background: rgba(0, 255, 255, 0.12);
    color: var(--primary-color);
    border-color: rgba(0, 255, 255, 0.3);
}

.english-lb-tab.active {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--background-color);
    border-color: var(--primary-color);
    box-shadow: 0 0 12px rgba(0, 255, 255, 0.3);
}

.english-lb-content {
    flex: 1;
    overflow-y: auto;
    padding: var(--space-lg) var(--space-xl);
    min-height: 200px;
}

.english-lb-loading {
    text-align: center;
    padding: var(--space-4xl) var(--space-xl);
    color: var(--light-text);
    font-size: 1.1rem;
}

.english-lb-loading::before {
    content: '';
    display: block;
    width: 36px;
    height: 36px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto var(--space-lg);
}

.english-lb-empty {
    text-align: center;
    padding: var(--space-4xl) var(--space-xl);
    color: var(--muted-text);
    font-size: 1.1rem;
}

.english-lb-empty::before {
    content: '📭';
    display: block;
    font-size: 3rem;
    margin-bottom: var(--space-md);
    opacity: 0.6;
}

.english-lb-table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    font-size: 0.9rem;
}

.english-lb-table thead th {
    color: var(--muted-text);
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 1px;
    padding: var(--space-sm) var(--space-md);
    text-align: left;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    background: var(--background-color);
    z-index: 1;
}

.english-lb-table tbody tr {
    transition: var(--transition-fast);
}

.english-lb-table tbody tr:hover {
    background: rgba(0, 255, 255, 0.05);
}

.english-lb-table td {
    padding: var(--space-sm) var(--space-md);
    border-bottom: 1px solid var(--border-light);
    color: var(--text-color);
    vertical-align: middle;
}

.english-lb-row.english-lb-top3 td {
    background: rgba(251, 191, 36, 0.04);
}

.english-lb-rank {
    font-weight: 700;
    text-align: center;
    width: 50px;
}

.english-lb-row:first-child .english-lb-rank {
    font-size: 1.3rem;
}

.english-lb-name {
    font-weight: 600;
    color: var(--primary-color);
    max-width: 120px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.english-lb-score {
    font-weight: 700;
    color: var(--success-color);
    text-shadow: 0 0 8px rgba(16, 185, 129, 0.3);
}

.english-lb-grade,
.english-lb-unit,
.english-lb-combo {
    color: var(--accent-color);
    text-align: center;
}

.english-lb-time {
    color: var(--secondary-color);
    font-family: var(--font-mono);
    font-size: 0.85rem;
}

.english-lb-date {
    color: var(--muted-text);
    font-size: 0.8rem;
}

/* 排行榜响应式 */
@media (max-width: 600px) {
    .english-lb-box {
        width: 98%;
        max-height: 90vh;
        border-radius: var(--border-radius);
    }

    .english-lb-header {
        padding: var(--space-md);
    }

    .english-lb-title {
        font-size: 1.2rem;
    }

    .english-lb-tabs {
        padding: var(--space-sm) var(--space-md);
    }

    .english-lb-tab {
        font-size: 0.8rem;
        padding: var(--space-xs) var(--space-md);
    }

    .english-lb-content {
        padding: var(--space-md);
    }

    .english-lb-table {
        font-size: 0.8rem;
    }

    .english-lb-table thead th {
        font-size: 0.65rem;
        padding: var(--space-xs) var(--space-sm);
    }

    .english-lb-table td {
        padding: var(--space-xs) var(--space-sm);
    }
}