/* 现代化英语学习系统样式 */
:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --success-color: #4facfe;
    --warning-color: #43e97b;
    --danger-color: #fa709a;
    --light-bg: #f8fafc;
    --white: #ffffff;
    --text-dark: #2d3748;
    --text-light: #718096;
    --border-radius: 12px;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.15);
    --shadow-lg: 0 8px 25px rgba(0,0,0,0.2);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    font-family: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-dark);
    line-height: 1.6;
    position: relative;
    overflow-x: hidden;
}

/* 背景动画 */
.animated-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

.floating-shapes {
    position: relative;
    width: 100%;
    height: 100%;
}

.shape {
    position: absolute;
    font-size: 2rem;
    opacity: 0.1;
    animation: float 6s ease-in-out infinite;
}

.shape-1 {
    top: 10%;
    left: 10%;
    animation-delay: 0s;
}

.shape-2 {
    top: 20%;
    right: 10%;
    animation-delay: 1s;
}

.shape-3 {
    top: 60%;
    left: 20%;
    animation-delay: 2s;
}

.shape-4 {
    bottom: 20%;
    right: 20%;
    animation-delay: 3s;
}

.shape-5 {
    bottom: 10%;
    left: 50%;
    animation-delay: 4s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px) rotate(0deg);
    }
    50% {
        transform: translateY(-20px) rotate(180deg);
    }
}

/* 导航栏样式 */
.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.navbar-brand {
    font-weight: 700;
    font-size: 1.5rem;
    background: linear-gradient(45deg, var(--primary-color), var(--accent-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-link {
    font-weight: 500;
    color: var(--text-dark) !important;
    transition: var(--transition);
    position: relative;
}

.nav-link:hover {
    color: var(--primary-color) !important;
    transform: translateY(-1px);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background: linear-gradient(45deg, var(--primary-color), var(--accent-color));
    transition: var(--transition);
    transform: translateX(-50%);
}

.nav-link:hover::after {
    width: 80%;
}

/* 容器样式 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

/* 输入框加载状态样式 */
.loading-input {
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%) !important;
    background-size: 200% 100% !important;
    animation: loading-shimmer 1.5s infinite !important;
    color: #999 !important;
    cursor: not-allowed !important;
}

.loading-input::placeholder {
    color: #666 !important;
    font-style: italic !important;
}

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

/* 卡片样式 */
.card, .mode-content {
    background: var(--white);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    border: none;
    overflow: hidden;
    transition: var(--transition);
}

.card:hover, .mode-content:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
    border: none;
    padding: 1.5rem;
    font-weight: 600;
}

.card-body {
    padding: 2rem;
}

/* 统计卡片 */
.stat-card {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 2rem 1.5rem;
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

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

.stat-card:hover {
    transform: translateY(-6px) scale(1.02);
    box-shadow: var(--shadow-lg);
}

.stat-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    display: block;
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.stat-label {
    color: #1ec296;
    font-weight: 500;
    font-size: 0.9rem;
    text-shadow: 0 0 2px rgba(44, 64, 150, 0.7)
}

/* 欢迎区域 */
.welcome-section {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 2.5rem;
    text-align: center;
    box-shadow: var(--shadow-md);
    margin-bottom: 2rem;
    position: relative;
    overflow: hidden;
}

.welcome-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.05), rgba(240, 147, 251, 0.05));
    z-index: 0;
}

.welcome-section > * {
    position: relative;
    z-index: 1;
}

.welcome-section h2 {
    background: linear-gradient(45deg, var(--primary-color), var(--accent-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
    margin-bottom: 1rem;
}

/* 模式选择器 */
.mode-selector .card {
    height: 100%;
    transition: var(--transition);
    cursor: pointer;
    border: 2px solid transparent;
}

.mode-selector .card:hover {
    border-color: var(--primary-color);
    transform: translateY(-8px) scale(1.03);
}

.mode-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    display: block;
}

.mode-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.mode-description {
    color: var(--text-light);
    font-size: 0.9rem;
}

/* 单词卡片 */
.word-card-container {
    max-width: 200%; /* 与col-md-8相同的宽度 */
    margin: 0 auto;
}

.word-card {
    background: linear-gradient(135deg, #9a6769, #bbbcb6);
    border-radius: var(--border-radius);
    margin: 1rem 0;
    padding: 1rem 2rem;
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    width: 100%;
    padding-top: 66.66%;
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.word-card:hover {
    transform: scale(1.02);
    box-shadow: var(--shadow-lg);
}

.word {
    font-family: 'Arial', sans-serif; /* 或者您喜欢的其他字体 */
    font-size: 3rem;
    font-weight: 1000;
    color: #333; /* 设置为深灰色，您可以根据需要调整颜色 */
    margin-bottom: 1rem;
    /* 添加底框突出显示 */
    padding: 20px 40px;
    border-radius: 15px;
    background: rgba(255, 255, 255, 0.95);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    border: 3px solid transparent;
    background-clip: padding-box;
    position: relative;
    display: inline-block;
}

.word::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    border-radius: 15px;
    padding: 3px;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    mask-composite: exclude;
    z-index: -1;
}

.word::after {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    border-radius: 17px;
    background: linear-gradient(45deg, var(--primary-color), var(--accent-color));
    z-index: -2;
    opacity: 0.3;
    filter: blur(8px);
}

.phonetic {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 1rem;
    font-style: italic;
}

.meaning {
    font-size: 1.3rem;
    color: var(--text-dark);
    font-weight: 500;
}

/* 游戏容器 */
.game-container {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    margin: 2rem 0;
}

.question {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 2rem;
    color: var(--text-dark);
    text-align: center;
}

.options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

/* 按钮样式 */
.btn {
    border-radius: var(--border-radius);
    font-weight: 600;
    padding: 0.75rem 1.5rem;
    transition: var(--transition);
    border: none;
    position: relative;
    overflow: hidden;
}

.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: var(--transition);
}

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

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    background: linear-gradient(135deg, var(--secondary-color), var(--primary-color));
}

.btn-success {
    background: linear-gradient(135deg, var(--success-color), var(--warning-color));
    color: var(--white);
}

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

.btn-outline-primary {
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    background: transparent;
}

.btn-outline-primary:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* 表单样式 */
.form-control {
    border-radius: var(--border-radius);
    border: 2px solid #e2e8f0;
    padding: 0.75rem 1rem;
    transition: var(--transition);
    font-size: 1rem;
}

.form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    outline: none;
    caret-color: #2d3748;
}

.form-label {
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

/* 进度条 */
.progress {
    height: 8px;
    border-radius: 4px;
    background-color: #e2e8f0;
    overflow: hidden;
}

.progress-bar {
    background: linear-gradient(90deg, var(--success-color), var(--warning-color));
    transition: var(--transition);
}

/* 词汇列表 */
.word-list-item {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border-left: 4px solid var(--primary-color);
}

.word-list-item:hover {
    transform: translateX(4px);
    box-shadow: var(--shadow-md);
}

/* 筛选器 */
.filter-section {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-sm);
}

/* 分页 */
.pagination {
    justify-content: center;
}

.page-link {
    border-radius: var(--border-radius);
    margin: 0 0.25rem;
    border: none;
    color: var(--primary-color);
    transition: var(--transition);
}

.page-link:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-1px);
}

.page-item.active .page-link {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border: none;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    .stat-card {
        margin-bottom: 1rem;
    }
    
    .word {
        font-size: 2rem;
    }
    
    .options {
        grid-template-columns: 1fr;
    }
    
    .welcome-section {
        padding: 1.5rem;
    }
}

/* 动画 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

.pulse {
    animation: pulse 2s infinite;
}

/* 工具类 */
.hidden {
    display: none !important;
}

.text-gradient {
    background: linear-gradient(45deg, var(--primary-color), var(--accent-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.glass-effect {
    background: rgba(255, 255, 255, 0.25);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.18);
}

/* 加载动画 */
.loading-spinner {
    width: 40px;
    height: 40px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 20px auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* 成功/错误提示 */
.alert {
    border-radius: var(--border-radius);
    border: none;
    padding: 1rem 1.5rem;
    margin-bottom: 1rem;
}

.alert-success {
    background: linear-gradient(135deg, rgba(79, 172, 254, 0.1), rgba(67, 233, 123, 0.1));
    color: var(--success-color);
    border-left: 4px solid var(--success-color);
}

.alert-danger {
    background: linear-gradient(135deg, rgba(250, 112, 154, 0.1), rgba(255, 94, 77, 0.1));
    color: var(--danger-color);
    border-left: 4px solid var(--danger-color);
}

/* 模态框 */
.modal-content {
    border-radius: var(--border-radius);
    border: none;
    box-shadow: var(--shadow-lg);
}

.modal-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
    border-bottom: none;
    border-radius: var(--border-radius) var(--border-radius) 0 0;
}

.modal-body {
    padding: 2rem;
}

/* 语音按钮 */
.voice-btn {
    background: linear-gradient(135deg, var(--accent-color), var(--primary-color));
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    color: var(--white);
    font-size: 1.2rem;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.voice-btn:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-md);
}

/* 难度标签 */
.difficulty-badge {
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
}

.difficulty-1 {
    background: linear-gradient(135deg, #4facfe, #00f2fe);
    color: var(--white);
}

.difficulty-2 {
    background: linear-gradient(135deg, #43e97b, #38f9d7);
    color: var(--white);
}

.difficulty-3 {
    background: linear-gradient(135deg, #fa709a, #fee140);
    color: var(--white);
}

.difficulty-4 {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: var(--white);
}

.difficulty-5 {
    background: linear-gradient(135deg, #f093fb, #f5576c);
    color: var(--white);
}