/* 小学英语同步学习平台 - 现代化样式 */

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

:root {
    /* 主色调 - 渐变蓝紫 */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-color: #667eea;
    --primary-dark: #5568d8;
    --secondary-color: #764ba2;
    
    /* 辅助色 */
    --success-color: #10b981;
    --success-light: #d1fae5;
    --warning-color: #f59e0b;
    --warning-light: #fef3c7;
    --danger-color: #ef4444;
    --danger-light: #fee2e2;
    --info-color: #3b82f6;
    --info-light: #dbeafe;
    
    /* 背景色 */
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
    
    /* 文字色 */
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    
    /* 边框 */
    --border-color: #e2e8f0;
    --border-light: #f1f5f9;
    
    /* 阴影 */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.3);
    
    /* 圆角 */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;
    
    /* 过渡 */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 夜间模式 */
body.dark-mode {
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-light: #64748b;
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --border-color: #334155;
    --border-light: #1e293b;
    --shadow-glow: 0 0 30px rgba(102, 126, 234, 0.5);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: var(--bg-gradient);
    background-attachment: fixed;
    min-height: 100vh;
    padding: 20px;
    color: var(--text-primary);
    transition: var(--transition);
    line-height: 1.6;
}

/* 主容器 */
.app-container {
    max-width: 1400px;
    margin: 0 auto;
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
    animation: slideUp 0.6s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========== 顶部导航 ========== */
.header {
    background: var(--primary-gradient);
    color: white;
    padding: 30px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 300px;
    height: 300px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    animation: float 6s ease-in-out infinite;
}

.header::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -5%;
    width: 200px;
    height: 200px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 50%;
    animation: float 8s ease-in-out infinite reverse;
}

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

.header-content {
    position: relative;
    z-index: 1;
}

.header-content h1 {
    font-size: 2em;
    margin-bottom: 8px;
    font-weight: 700;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.header-content .subtitle {
    opacity: 0.95;
    font-size: 1em;
    font-weight: 400;
}

.header-actions {
    display: flex;
    gap: 12px;
    position: relative;
    z-index: 1;
}

.btn-icon {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: 10px 16px;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.95em;
    transition: var(--transition);
    font-weight: 500;
}

.btn-icon:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-icon:active {
    transform: translateY(0);
}

/* ========== 控制面板 ========== */
.control-panel {
    background: var(--bg-primary);
    padding: 24px 40px;
    border-bottom: 1px solid var(--border-color);
}

.version-selector, .grade-selector, .semester-selector {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.version-selector:last-child, .grade-selector:last-child, .semester-selector:last-child {
    margin-bottom: 0;
}

.version-selector label, 
.grade-selector label, 
.semester-selector label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95em;
    min-width: 100px;
}

.version-selector select {
    padding: 10px 20px;
    font-size: 0.95em;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-full);
    background: var(--bg-secondary);
    cursor: pointer;
    min-width: 280px;
    transition: var(--transition);
    color: var(--text-primary);
    font-weight: 500;
}

.version-selector select:hover {
    border-color: var(--primary-color);
}

.version-selector select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.version-description {
    color: var(--text-secondary);
    font-size: 0.85em;
    margin-left: 8px;
    font-style: italic;
}

.grade-buttons {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.grade-btn, .semester-btn {
    padding: 10px 20px;
    border: 2px solid var(--border-color);
    background: var(--bg-secondary);
    color: var(--text-secondary);
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.9em;
    transition: var(--transition);
    font-weight: 500;
}

.grade-btn:hover, .grade-btn.active,
.semester-btn:hover, .semester-btn.active {
    background: var(--primary-gradient);
    color: white;
    border-color: transparent;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.grade-btn:active, .semester-btn:active {
    transform: translateY(0);
}

/* ========== 单元导航 ========== */
.unit-nav {
    background: var(--bg-primary);
    padding: 24px 40px;
    border-bottom: 1px solid var(--border-color);
}

.unit-nav h3 {
    margin-bottom: 16px;
    color: var(--text-primary);
    font-size: 1.1em;
    font-weight: 600;
}

.unit-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.unit-btn {
    padding: 14px 24px;
    border: 2px solid var(--border-color);
    background: var(--bg-secondary);
    color: var(--text-primary);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.95em;
    transition: var(--transition);
    min-width: 140px;
    font-weight: 500;
    text-align: left;
}

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

.unit-btn.active {
    background: var(--primary-gradient);
    color: white;
    border-color: transparent;
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.unit-btn .unit-status {
    display: block;
    font-size: 0.8em;
    margin-top: 4px;
    opacity: 0.7;
}

/* ========== 主容器 ========== */
.main-container {
    display: flex;
    min-height: 600px;
}

/* ========== 侧边栏 ========== */
.sidebar {
    width: 280px;
    background: var(--bg-primary);
    border-right: 1px solid var(--border-color);
    padding: 24px;
    flex-shrink: 0;
}

.mode-nav {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 32px;
}

.mode-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 18px;
    border: none;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.95em;
    transition: var(--transition);
    text-align: left;
    font-weight: 500;
    border: 2px solid transparent;
}

.mode-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateX(4px);
}

.mode-btn.active {
    background: var(--primary-gradient);
    color: white;
    box-shadow: var(--shadow-md);
    transform: translateX(4px);
}

.mode-icon {
    font-size: 1.3em;
    width: 24px;
    text-align: center;
}

/* ========== 单元信息 ========== */
.unit-info {
    background: var(--bg-secondary);
    padding: 24px;
    border-radius: var(--radius-lg);
    text-align: center;
    border: 1px solid var(--border-color);
}

.unit-info h4 {
    color: var(--text-secondary);
    margin-bottom: 12px;
    font-size: 0.9em;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

#current-unit-name {
    font-weight: 700;
    margin-bottom: 20px;
    font-size: 1.1em;
    color: var(--text-primary);
}

.progress-ring {
    position: relative;
    display: inline-block;
    margin-bottom: 12px;
}

.progress-ring svg {
    transform: rotate(-90deg);
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
}

.progress-ring-bg {
    fill: none;
    stroke: var(--border-color);
    stroke-width: 6;
}

.progress-ring-fill {
    fill: none;
    stroke: url(#progressGradient);
    stroke-width: 6;
    stroke-linecap: round;
    stroke-dasharray: 226;
    stroke-dashoffset: 226;
    transition: stroke-dashoffset 0.5s ease;
}

.progress-percent {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-weight: 700;
    font-size: 1.1em;
    color: var(--primary-color);
}

.progress-detail {
    font-size: 0.85em;
    color: var(--text-secondary);
}

/* ========== 内容区域 ========== */
.content-area {
    flex: 1;
    padding: 32px 40px;
    overflow-y: auto;
    max-height: 800px;
}

.content-area::-webkit-scrollbar {
    width: 8px;
}

.content-area::-webkit-scrollbar-track {
    background: var(--bg-primary);
    border-radius: 4px;
}

.content-area::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 4px;
}

.content-section {
    display: none;
    animation: fadeIn 0.4s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.content-section.active {
    display: block;
}

/* ========== 单词学习区域 ========== */
.word-list-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    flex-wrap: wrap;
    gap: 16px;
}

.word-list-header h3 {
    color: var(--text-primary);
    font-size: 1.5em;
    font-weight: 700;
}

.word-list-actions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.btn-action {
    padding: 10px 20px;
    border: none;
    background: var(--primary-gradient);
    color: white;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.9em;
    transition: var(--transition);
    font-weight: 500;
    box-shadow: var(--shadow-sm);
}

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

.btn-action:active {
    transform: translateY(0);
}

/* ========== 单词卡片 ========== */
.word-card-view {
    max-width: 700px;
    margin: 0 auto;
}

.progress-bar {
    background: var(--bg-primary);
    height: 8px;
    border-radius: var(--radius-full);
    margin-bottom: 24px;
    position: relative;
    overflow: hidden;
    box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.05);
}

.progress-fill {
    background: var(--primary-gradient);
    height: 100%;
    width: 0%;
    border-radius: var(--radius-full);
    transition: width 0.4s ease;
    box-shadow: 0 0 10px rgba(102, 126, 234, 0.5);
}

.progress-text {
    position: absolute;
    right: 0;
    top: -28px;
    font-size: 0.9em;
    color: var(--text-secondary);
    font-weight: 500;
}

.word-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 48px;
    text-align: center;
    margin-bottom: 32px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.word-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
}

.word-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.word-index {
    background: var(--primary-gradient);
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1em;
    box-shadow: var(--shadow-md);
}

.btn-favorite {
    background: none;
    border: none;
    font-size: 2em;
    cursor: pointer;
    color: var(--text-light);
    transition: var(--transition);
    filter: grayscale(100%);
}

.btn-favorite:hover {
    transform: scale(1.2) rotate(10deg);
    filter: grayscale(0%);
}

.btn-favorite.active {
    color: var(--warning-color);
    filter: grayscale(0%);
}

.english-word {
    font-size: 3.5em;
    color: var(--text-primary);
    margin-bottom: 12px;
    font-weight: 800;
    letter-spacing: -1px;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.phonetic {
    font-size: 1.4em;
    color: var(--primary-color);
    margin-bottom: 16px;
    font-family: 'Courier New', monospace;
    font-weight: 500;
}

.chinese-meaning {
    font-size: 2em;
    color: var(--text-primary);
    font-weight: 700;
    margin-bottom: 8px;
}

.word-tags {
    margin-top: 20px;
    display: flex;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
}

.word-tag {
    padding: 6px 14px;
    background: var(--primary-gradient);
    color: white;
    border-radius: var(--radius-full);
    font-size: 0.8em;
    font-weight: 500;
    box-shadow: var(--shadow-sm);
}

.word-actions {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-top: 32px;
    flex-wrap: wrap;
}

.btn-speak, .btn-example {
    padding: 14px 28px;
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 1em;
    transition: var(--transition);
    font-weight: 600;
    box-shadow: var(--shadow-md);
}

.btn-speak {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
}

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

.btn-example {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
}

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

.example-sentence {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: 24px;
    margin-top: 24px;
    text-align: left;
    border-left: 4px solid var(--primary-color);
}

.sentence-en {
    font-size: 1.2em;
    color: var(--text-primary);
    margin-bottom: 8px;
    font-weight: 500;
}

.sentence-cn {
    font-size: 1em;
    color: var(--text-secondary);
}

.btn-speak-small {
    background: var(--primary-gradient);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: var(--radius-full);
    cursor: pointer;
    margin-top: 12px;
    font-weight: 500;
    transition: var(--transition);
}

.btn-speak-small:hover {
    transform: scale(1.05);
}

.navigation {
    display: flex;
    justify-content: space-between;
    gap: 16px;
}

.nav-btn {
    flex: 1;
    padding: 14px 24px;
    border: none;
    background: var(--primary-gradient);
    color: white;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 1em;
    transition: var(--transition);
    font-weight: 600;
    box-shadow: var(--shadow-md);
}

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

.nav-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* ========== 单词列表视图 ========== */
.word-list-view {
    overflow-x: auto;
    border-radius: var(--radius-lg);
}

.word-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.word-table th, .word-table td {
    padding: 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.word-table th {
    background: var(--primary-gradient);
    color: white;
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.85em;
    letter-spacing: 0.5px;
}

.word-table tr {
    transition: var(--transition);
}

.word-table tr:hover {
    background: var(--bg-primary);
}

.word-table-actions {
    display: flex;
    gap: 8px;
}

.btn-table-action {
    padding: 6px 12px;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.85em;
    transition: var(--transition);
}

.btn-speak-sm {
    background: var(--success-color);
    color: white;
}

.btn-fav-sm {
    background: var(--warning-color);
    color: white;
}

/* ========== 课文区域 ========== */
.text-nav {
    margin-bottom: 24px;
}

.text-nav h3 {
    margin-bottom: 12px;
    color: var(--text-primary);
    font-size: 1.2em;
}

.text-nav select {
    width: 100%;
    padding: 14px 20px;
    font-size: 1em;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    cursor: pointer;
    transition: var(--transition);
    color: var(--text-primary);
}

.text-nav select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.text-content {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 40px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
}

.text-content h3 {
    color: var(--text-primary);
    margin-bottom: 24px;
    font-size: 1.8em;
    font-weight: 700;
}

.text-line {
    display: flex;
    align-items: center;
    padding: 20px 16px;
    border-bottom: 1px dashed var(--border-color);
    transition: var(--transition);
    border-radius: var(--radius-md);
}

.text-line:hover {
    background: var(--bg-primary);
    transform: translateX(4px);
}

.text-line:last-child {
    border-bottom: none;
}

.text-en {
    flex: 2;
    font-size: 1.2em;
    color: var(--text-primary);
    font-weight: 500;
}

.text-cn {
    flex: 2;
    font-size: 1em;
    color: var(--text-secondary);
}

.btn-speak-line {
    background: var(--primary-gradient);
    color: white;
    border: none;
    padding: 10px 18px;
    border-radius: var(--radius-full);
    cursor: pointer;
    margin-left: 16px;
    transition: var(--transition);
    font-weight: 500;
}

.btn-speak-line:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
}

.text-actions {
    margin-top: 24px;
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.btn-speak-full {
    padding: 14px 28px;
    border: none;
    background: var(--primary-gradient);
    color: white;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 1em;
    transition: var(--transition);
    font-weight: 600;
    box-shadow: var(--shadow-md);
}

.btn-speak-full:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* ========== 听写区域 ========== */
.dictation-container {
    max-width: 700px;
    margin: 0 auto;
    text-align: center;
}

.dictation-container h3 {
    color: var(--text-primary);
    margin-bottom: 12px;
    font-size: 1.8em;
    font-weight: 700;
}

.dictation-instruction {
    color: var(--text-secondary);
    margin-bottom: 24px;
    font-size: 1em;
}

.dictation-controls {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.btn-dictation {
    padding: 12px 24px;
    border: none;
    background: var(--primary-gradient);
    color: white;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.95em;
    transition: var(--transition);
    font-weight: 600;
    box-shadow: var(--shadow-md);
}

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

.dictation-area {
    background: var(--bg-secondary);
    padding: 32px;
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
}

.dictation-progress {
    margin-bottom: 24px;
    font-size: 1.1em;
    color: var(--text-secondary);
    font-weight: 500;
}

.dictation-input {
    width: 100%;
    padding: 16px;
    font-size: 1.8em;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    text-align: center;
    margin-bottom: 20px;
    transition: var(--transition);
    color: var(--text-primary);
    background: var(--bg-primary);
    font-weight: 600;
}

.dictation-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
}

.dictation-feedback {
    font-size: 1.3em;
    font-weight: 700;
    min-height: 40px;
    margin-bottom: 16px;
}

.dictation-feedback.correct {
    color: var(--success-color);
}

.dictation-feedback.wrong {
    color: var(--danger-color);
}

.dictation-answer {
    margin-top: 16px;
    padding: 16px;
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    font-size: 1.2em;
    color: var(--primary-color);
    font-weight: 600;
}

.dictation-result {
    margin-top: 32px;
    padding: 32px;
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
}

.dictation-result h4 {
    color: var(--text-primary);
    margin-bottom: 16px;
    font-size: 1.5em;
}

/* ========== 测试区域 ========== */
.test-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    flex-wrap: wrap;
    gap: 16px;
}

.test-header h3 {
    color: var(--text-primary);
    font-size: 1.5em;
}

.test-info {
    display: flex;
    gap: 24px;
    font-size: 1em;
    color: var(--text-secondary);
}

.test-info strong {
    color: var(--primary-color);
}

.test-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 48px;
    text-align: center;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
}

.test-card h4 {
    margin-bottom: 24px;
    color: var(--text-primary);
    font-size: 1.3em;
}

.btn-listen {
    padding: 14px 28px;
    border: none;
    background: var(--primary-gradient);
    color: white;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 1em;
    transition: var(--transition);
    font-weight: 600;
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
}

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

.options {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    margin-top: 24px;
}

.option-btn {
    padding: 20px;
    border: 2px solid var(--border-color);
    background: var(--bg-primary);
    color: var(--text-primary);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 1.05em;
    transition: var(--transition);
    font-weight: 500;
}

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

.option-btn.correct {
    background: var(--success-light);
    color: var(--success-color);
    border-color: var(--success-color);
}

.option-btn.wrong {
    background: var(--danger-light);
    color: var(--danger-color);
    border-color: var(--danger-color);
}

.test-result, .test-final-result {
    margin-top: 24px;
    padding: 24px;
    border-radius: var(--radius-lg);
    text-align: center;
}

.test-result.correct, .test-final-result {
    background: var(--success-light);
    color: var(--success-color);
}

.test-result.wrong {
    background: var(--danger-light);
    color: var(--danger-color);
}

.final-score {
    font-size: 4em;
    font-weight: 800;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin: 20px 0;
}

.score-label {
    font-size: 0.4em;
}

#final-comment {
    font-size: 1.3em;
    margin-bottom: 20px;
    font-weight: 600;
}

/* ========== 标签区域 ========== */
.tags-filter {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 24px;
    margin-bottom: 24px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
}

.tags-filter h3 {
    color: var(--text-primary);
    margin-bottom: 16px;
    font-size: 1.3em;
}

.tags-list {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.tag-btn {
    padding: 10px 20px;
    border: 2px solid var(--border-color);
    background: var(--bg-primary);
    color: var(--text-secondary);
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.9em;
    transition: var(--transition);
    font-weight: 500;
}

.tag-btn:hover, .tag-btn.active {
    background: var(--primary-gradient);
    color: white;
    border-color: transparent;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.tagged-words {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 24px;
    border: 1px solid var(--border-color);
}

.tag-hint {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.05em;
    padding: 20px;
}

.tagged-word-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 16px;
}

.tagged-word-item {
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    padding: 16px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.tagged-word-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.tagged-word-item .en {
    font-size: 1.2em;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.tagged-word-item .cn {
    font-size: 0.9em;
    color: var(--text-secondary);
}

/* ========== 收藏区域 ========== */
#favorites-section h3 {
    color: var(--text-primary);
    margin-bottom: 24px;
    font-size: 1.5em;
}

.favorites-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 16px;
}

.favorite-item {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.favorite-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.favorite-word {
    font-size: 1.4em;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 4px;
}

.favorite-meaning {
    font-size: 0.9em;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.btn-remove-fav {
    background: var(--danger-color);
    color: white;
    border: none;
    padding: 8px 12px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
}

.btn-remove-fav:hover {
    background: #dc2626;
    transform: scale(1.05);
}

.empty-hint {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1em;
    padding: 60px 20px;
}

/* ========== 统计区域 ========== */
#stats-section h3 {
    color: var(--text-primary);
    margin-bottom: 24px;
    font-size: 1.5em;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 32px;
}

.stat-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 24px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.stat-card h4 {
    color: var(--text-secondary);
    margin-bottom: 12px;
    font-size: 0.9em;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.stat-value {
    font-size: 2.2em;
    font-weight: 800;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stats-chart {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 32px;
    margin-bottom: 24px;
    border: 1px solid var(--border-color);
}

.stats-chart h4 {
    color: var(--text-primary);
    margin-bottom: 24px;
    font-size: 1.2em;
}

.progress-bars {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.unit-progress-bar {
    display: flex;
    align-items: center;
    gap: 16px;
}

.unit-progress-bar .unit-name {
    min-width: 120px;
    font-weight: 600;
    color: var(--text-primary);
}

.unit-progress-bar .progress-track {
    flex: 1;
    height: 24px;
    background: var(--bg-primary);
    border-radius: var(--radius-full);
    overflow: hidden;
    box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.05);
}

.unit-progress-bar .progress-fill-sm {
    height: 100%;
    background: var(--primary-gradient);
    border-radius: var(--radius-full);
    transition: width 0.5s ease;
    box-shadow: 0 0 10px rgba(102, 126, 234, 0.5);
}

.unit-progress-bar .progress-text-sm {
    min-width: 100px;
    text-align: right;
    font-size: 0.9em;
    color: var(--text-secondary);
    font-weight: 600;
}

/* ========== 设置面板 ========== */
.settings-panel {
    background: var(--bg-primary);
    padding: 24px 40px;
    border-top: 1px solid var(--border-color);
}

.settings-panel h4 {
    color: var(--text-primary);
    margin-bottom: 20px;
    font-size: 1.1em;
}

.setting-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.setting-item {
    display: flex;
    align-items: center;
    gap: 16px;
}

.setting-item label {
    min-width: 100px;
    color: var(--text-secondary);
    font-weight: 500;
}

.setting-item input[type="range"] {
    flex: 1;
    height: 6px;
    border-radius: 3px;
    background: var(--border-color);
    outline: none;
}

.setting-item input[type="range"]::-webkit-slider-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-gradient);
    cursor: pointer;
    box-shadow: var(--shadow-md);
}

.setting-item select {
    flex: 1;
    padding: 10px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-full);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 0.95em;
}

.btn-reset {
    padding: 10px 20px;
    border: none;
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.9em;
    transition: var(--transition);
    font-weight: 600;
}

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

/* ========== 页脚 ========== */
.footer {
    background: var(--text-primary);
    color: white;
    text-align: center;
    padding: 24px;
    font-size: 0.9em;
}

/* ========== 响应式设计 ========== */
@media (max-width: 1024px) {
    .main-container {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
        border-right: none;
        border-bottom: 1px solid var(--border-color);
    }

    .mode-nav {
        flex-direction: row;
        flex-wrap: wrap;
    }

    .mode-btn {
        flex: 1;
        min-width: 150px;
        justify-content: center;
    }
}

@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    .app-container {
        border-radius: var(--radius-lg);
    }

    .header {
        flex-direction: column;
        gap: 16px;
        text-align: center;
        padding: 24px 20px;
    }

    .header-content h1 {
        font-size: 1.6em;
    }

    .control-panel, .unit-nav, .content-area, .settings-panel {
        padding: 20px;
    }

    .word-list-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .word-list-actions {
        width: 100%;
    }

    .options {
        grid-template-columns: 1fr;
    }

    .english-word {
        font-size: 2.5em;
    }

    .chinese-meaning {
        font-size: 1.5em;
    }

    .word-card {
        padding: 32px 24px;
    }

    .grade-buttons {
        flex-direction: column;
    }

    .unit-buttons {
        flex-direction: column;
    }

    .dictation-controls {
        flex-direction: column;
    }

    .test-info {
        flex-direction: column;
        gap: 12px;
    }
}

/* ========== 拼写练习 ========== */
.spelling-container {
    max-width: 700px;
    margin: 0 auto;
    text-align: center;
}

.spelling-container h3 {
    color: var(--text-primary);
    margin-bottom: 12px;
    font-size: 1.8em;
    font-weight: 700;
}

.spelling-instruction {
    color: var(--text-secondary);
    margin-bottom: 24px;
    font-size: 1em;
}

.spelling-controls {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.btn-spelling {
    padding: 12px 24px;
    border: none;
    background: var(--primary-gradient);
    color: white;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.95em;
    transition: var(--transition);
    font-weight: 600;
    box-shadow: var(--shadow-md);
}

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

.spelling-area {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 40px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
}

.spelling-progress {
    margin-bottom: 24px;
    font-size: 1.1em;
    color: var(--text-secondary);
    font-weight: 600;
}

.spelling-meaning {
    font-size: 1.5em;
    color: var(--primary-color);
    margin-bottom: 24px;
    font-weight: 700;
}

.spelling-input {
    width: 100%;
    padding: 16px 24px;
    font-size: 1.5em;
    border: 3px solid var(--border-color);
    border-radius: var(--radius-lg);
    text-align: center;
    font-weight: 700;
    letter-spacing: 2px;
    transition: var(--transition);
    color: var(--text-primary);
    background: var(--bg-primary);
}

.spelling-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.2);
}

.spelling-input:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.spelling-feedback {
    margin-top: 20px;
    font-size: 1.2em;
    font-weight: 700;
    min-height: 30px;
}

.spelling-feedback.correct {
    color: var(--success-color);
}

.spelling-feedback.wrong {
    color: var(--danger-color);
}

.spelling-hint {
    margin-top: 16px;
    padding: 12px 20px;
    background: var(--warning-light);
    border-radius: var(--radius-md);
    font-size: 1em;
    color: var(--text-primary);
    border-left: 4px solid var(--warning-color);
}

.spelling-result {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: 40px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
}

.spelling-result h4 {
    color: var(--text-primary);
    margin-bottom: 20px;
    font-size: 1.6em;
    font-weight: 700;
}

.spelling-result p {
    font-size: 1.1em;
    margin-bottom: 12px;
    color: var(--text-secondary);
}

.spelling-result strong {
    color: var(--primary-color);
    font-size: 1.3em;
}

.spelling-review {
    margin-top: 24px;
    text-align: left;
}

.spelling-review h5 {
    color: var(--text-primary);
    margin-bottom: 16px;
    font-size: 1.1em;
}

.review-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    background: var(--danger-light);
    border-radius: var(--radius-md);
    margin-bottom: 8px;
    border-left: 4px solid var(--danger-color);
}

.review-item.wrong {
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.review-word {
    font-weight: 700;
    color: var(--text-primary);
    font-size: 1.1em;
}

.review-meaning {
    color: var(--text-secondary);
    font-size: 0.95em;
}

.perfect-score {
    text-align: center;
    font-size: 1.3em;
    color: var(--success-color);
    font-weight: 700;
    padding: 20px;
    background: var(--success-light);
    border-radius: var(--radius-lg);
}

/* ========== 统计操作按钮 ========== */
.stats-actions {
    display: flex;
    gap: 12px;
    margin-top: 24px;
    justify-content: center;
    flex-wrap: wrap;
}

/* ========== 打印样式 ========== */
@media print {
    body {
        background: white;
        padding: 0;
    }

    .app-container {
        box-shadow: none;
        border-radius: 0;
    }

    .header, .control-panel, .unit-nav, .sidebar, .settings-panel, .footer,
    .word-actions, .navigation, .btn-action {
        display: none !important;
    }

    .main-container {
        display: block;
    }

    .content-area {
        padding: 0;
        max-height: none;
    }

    .word-table {
        border: 1px solid #333;
    }

    .word-table th, .word-table td {
        border: 1px solid #333;
    }
}