/* ===== 全局变量与重置 ===== */
:root {
    --primary: #4a6cf7;
    --primary-dark: #3a56d4;
    --primary-light: #e8edff;
    --secondary: #f0a500;
    --success: #28a745;
    --danger: #dc3545;
    --warning: #ffc107;
    --info: #17a2b8;
    --dark: #1a1a2e;
    --light: #f8f9fa;
    --gray: #6c757d;
    --gray-light: #e9ecef;
    --border: #dee2e6;
    --bg: #f0f2f5;
    --card-bg: #ffffff;
    --text: #333;
    --text-secondary: #666;
    --shadow: 0 2px 8px rgba(0,0,0,0.1);
    --shadow-hover: 0 4px 16px rgba(0,0,0,0.15);
    --radius: 12px;
    --radius-sm: 8px;
    --sidebar-width: 240px;
    --header-height: 60px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    overflow: hidden;
    height: 100vh;
}

#app {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

/* ===== 顶部导航栏 ===== */
.app-header {
    height: var(--header-height);
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
    box-shadow: var(--shadow);
    z-index: 100;
    flex-shrink: 0;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 15px;
}

.menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-around;
    width: 28px;
    height: 28px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
}

.menu-toggle span {
    display: block;
    width: 100%;
    height: 3px;
    background: white;
    border-radius: 2px;
    transition: var(--transition);
}

.app-title {
    font-size: 20px;
    font-weight: 600;
    white-space: nowrap;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 15px;
}

.progress-bar-container {
    display: flex;
    align-items: center;
    gap: 8px;
    background: rgba(255,255,255,0.2);
    border-radius: 20px;
    padding: 4px 12px;
    width: 200px;
}

.progress-bar {
    height: 8px;
    background: var(--success);
    border-radius: 4px;
    width: 0%;
    transition: width 0.5s ease;
    max-width: 150px;
}

.progress-text {
    font-size: 13px;
    font-weight: 600;
    white-space: nowrap;
}

/* ===== 主布局 ===== */
.main-body {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* ===== 侧边栏 ===== */
.sidebar {
    width: var(--sidebar-width);
    background: var(--card-bg);
    box-shadow: 2px 0 8px rgba(0,0,0,0.05);
    overflow-y: auto;
    flex-shrink: 0;
    transition: var(--transition);
}

.sidebar::-webkit-scrollbar {
    width: 6px;
}

.sidebar::-webkit-scrollbar-thumb {
    background: var(--gray-light);
    border-radius: 3px;
}

.nav-menu {
    padding: 10px 0;
}

.nav-section {
    margin-bottom: 5px;
}

.nav-section-title {
    padding: 8px 20px;
    font-size: 12px;
    font-weight: 700;
    color: var(--gray);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 20px;
    color: var(--text);
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    font-size: 14px;
    border-left: 3px solid transparent;
}

.nav-item:hover {
    background: var(--primary-light);
    color: var(--primary);
}

.nav-item.active {
    background: var(--primary-light);
    color: var(--primary);
    border-left-color: var(--primary);
    font-weight: 600;
}

.nav-icon {
    font-size: 16px;
    width: 20px;
    text-align: center;
}

/* ===== 主内容区 ===== */
.content {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
}

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

.content::-webkit-scrollbar-thumb {
    background: var(--gray-light);
    border-radius: 4px;
}

.content::-webkit-scrollbar-thumb:hover {
    background: var(--gray);
}

/* ===== 通用组件 ===== */
.page-title {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--dark);
}

.section-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
    margin-bottom: 20px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}

.btn-primary {
    background: var(--primary);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-hover);
}

.btn-secondary {
    background: var(--gray-light);
    color: var(--text);
}

.btn-secondary:hover {
    background: var(--border);
}

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

.btn-danger {
    background: var(--danger);
    color: white;
}

.btn-warning {
    background: var(--warning);
    color: var(--dark);
}

.btn-sm {
    padding: 6px 12px;
    font-size: 12px;
}

.btn-lg {
    padding: 14px 28px;
    font-size: 16px;
}

/* ===== 章节网格 ===== */
.chapter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
    margin-bottom: 20px;
}

.chapter-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 20px;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.chapter-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}

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

.chapter-card.completed::before {
    background: var(--success);
}

.chapter-card.in-progress::before {
    background: var(--warning);
}

.chapter-number {
    font-size: 13px;
    color: var(--gray);
    margin-bottom: 4px;
}

.chapter-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 8px;
}

.chapter-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 12px;
    color: var(--gray);
}

.chapter-status {
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    display: inline-block;
}

.status-dot.completed { background: var(--success); }
.status-dot.in-progress { background: var(--warning); }
.status-dot.not-started { background: var(--gray-light); }

/* ===== 词汇学习页面 ===== */
.vocab-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.vocab-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 16px;
    background: var(--card-bg);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border-left: 4px solid var(--primary);
}

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

.vocab-item .word-image {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-sm);
    object-fit: cover;
    cursor: pointer;
    flex-shrink: 0;
    background: var(--gray-light);
}

.vocab-item .word-image-placeholder {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-sm);
    background: var(--primary-light);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    cursor: pointer;
    flex-shrink: 0;
    transition: var(--transition);
}

.vocab-item .word-image-placeholder:hover {
    background: var(--primary);
    color: white;
}

.vocab-info {
    flex: 1;
}

.vocab-word {
    font-size: 20px;
    font-weight: 700;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.vocab-phonetic {
    font-size: 14px;
    color: var(--gray);
    font-style: italic;
}

.speaker-btn {
    background: none;
    border: none;
    color: var(--primary);
    cursor: pointer;
    font-size: 18px;
    padding: 2px 6px;
    border-radius: 4px;
    transition: var(--transition);
}

.speaker-btn:hover {
    background: var(--primary-light);
}

.vocab-meaning {
    font-size: 15px;
    color: var(--text);
    margin: 4px 0;
}

.vocab-usage {
    font-size: 13px;
    color: var(--text-secondary);
    background: var(--light);
    padding: 8px 12px;
    border-radius: 6px;
    margin-top: 4px;
}

.vocab-usage .usage-label {
    font-weight: 600;
    color: var(--primary);
}

/* ===== 练习页面 ===== */
.practice-container {
    max-width: 800px;
    margin: 0 auto;
}

.question-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
    margin-bottom: 20px;
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--gray-light);
}

.question-type-badge {
    background: var(--primary-light);
    color: var(--primary);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 600;
}

.question-number {
    font-size: 14px;
    color: var(--gray);
}

.question-text {
    font-size: 18px;
    color: var(--dark);
    margin-bottom: 20px;
    line-height: 1.8;
}

.question-text .blank {
    display: inline-block;
    min-width: 120px;
    border-bottom: 2px solid var(--primary);
    margin: 0 4px;
}

.answer-input-group {
    margin-bottom: 16px;
}

.answer-input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 16px;
    transition: var(--transition);
    outline: none;
}

.answer-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(74, 108, 247, 0.1);
}

.options-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
}

.option-item:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}

.option-item.selected {
    border-color: var(--primary);
    background: var(--primary-light);
}

.option-item.correct {
    border-color: var(--success);
    background: rgba(40, 167, 69, 0.1);
}

.option-item.wrong {
    border-color: var(--danger);
    background: rgba(220, 53, 69, 0.1);
}

.option-label {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--gray-light);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 14px;
    flex-shrink: 0;
}

.option-item.selected .option-label {
    background: var(--primary);
    color: white;
}

.option-item.correct .option-label {
    background: var(--success);
    color: white;
}

.option-item.wrong .option-label {
    background: var(--danger);
    color: white;
}

.option-text {
    flex: 1;
    font-size: 15px;
}

.feedback-box {
    margin-top: 16px;
    padding: 16px;
    border-radius: var(--radius-sm);
    display: none;
}

.feedback-box.show {
    display: block;
    animation: fadeIn 0.3s ease;
}

.feedback-box.correct {
    background: rgba(40, 167, 69, 0.1);
    border: 1px solid var(--success);
}

.feedback-box.wrong {
    background: rgba(220, 53, 69, 0.1);
    border: 1px solid var(--danger);
}

.feedback-title {
    font-weight: 700;
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.feedback-title.correct { color: var(--success); }
.feedback-title.wrong { color: var(--danger); }

.feedback-detail {
    font-size: 14px;
    color: var(--text);
}

.feedback-detail strong {
    color: var(--primary);
}

.practice-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 20px;
}

.practice-stats {
    display: flex;
    gap: 20px;
    font-size: 14px;
    color: var(--gray);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 6px;
}

.stat-item .stat-value {
    font-weight: 700;
    font-size: 18px;
}

.stat-item.correct .stat-value { color: var(--success); }
.stat-item.wrong .stat-value { color: var(--danger); }

/* ===== 语法学习页面 ===== */
.grammar-content {
    line-height: 1.8;
}

.grammar-title {
    font-size: 22px;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--primary);
}

.grammar-section {
    margin-bottom: 20px;
}

.grammar-section h3 {
    font-size: 18px;
    color: var(--primary-dark);
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.grammar-section p {
    font-size: 15px;
    margin-bottom: 10px;
    color: var(--text);
}

.grammar-example {
    background: var(--light);
    border-left: 4px solid var(--secondary);
    padding: 12px 16px;
    margin: 10px 0;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    font-size: 14px;
}

.grammar-example .ex-label {
    font-weight: 700;
    color: var(--secondary);
}

.grammar-table {
    width: 100%;
    border-collapse: collapse;
    margin: 12px 0;
    font-size: 14px;
}

.grammar-table th,
.grammar-table td {
    border: 1px solid var(--border);
    padding: 8px 12px;
    text-align: left;
}

.grammar-table th {
    background: var(--primary-light);
    color: var(--primary);
    font-weight: 600;
}

.grammar-table tr:nth-child(even) {
    background: var(--light);
}

.grammar-tip {
    background: rgba(255, 193, 7, 0.1);
    border: 1px solid var(--warning);
    border-radius: var(--radius-sm);
    padding: 12px 16px;
    margin: 12px 0;
    font-size: 14px;
}

.grammar-tip::before {
    content: '💡 提示: ';
    font-weight: 700;
    color: var(--warning);
}

/* ===== 应用文页面 ===== */
.writing-section {
    margin-bottom: 24px;
}

.writing-section-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--primary-dark);
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 8px;
}

.golden-sentence {
    background: linear-gradient(135deg, #fff9e6 0%, #fff3d4 100%);
    border-left: 4px solid var(--secondary);
    padding: 16px;
    margin: 10px 0;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    position: relative;
    transition: var(--transition);
}

.golden-sentence:hover {
    transform: translateX(4px);
    box-shadow: var(--shadow);
}

.golden-sentence .gs-english {
    font-size: 15px;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 6px;
}

.golden-sentence .gs-chinese {
    font-size: 13px;
    color: var(--text-secondary);
}

.golden-sentence .gs-tag {
    position: absolute;
    top: 8px;
    right: 12px;
    font-size: 11px;
    color: var(--secondary);
    font-weight: 600;
}

.writing-template {
    background: var(--light);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px;
    margin: 12px 0;
}

.writing-template h4 {
    color: var(--primary);
    margin-bottom: 8px;
    font-size: 15px;
}

.writing-template p {
    font-size: 14px;
    line-height: 1.8;
    margin-bottom: 6px;
}

/* ===== 阅读页面 ===== */
.reading-search-bar {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.reading-search-input {
    flex: 1;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    outline: none;
    transition: var(--transition);
}

.reading-search-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(74, 108, 247, 0.1);
}

.reading-article {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
    margin-bottom: 20px;
}

.reading-article h3 {
    font-size: 20px;
    color: var(--dark);
    margin-bottom: 8px;
}

.reading-meta {
    font-size: 13px;
    color: var(--gray);
    margin-bottom: 16px;
    display: flex;
    gap: 16px;
}

.reading-content {
    font-size: 15px;
    line-height: 2;
    color: var(--text);
}

.reading-content .vocab-highlight {
    background: var(--primary-light);
    color: var(--primary);
    padding: 1px 4px;
    border-radius: 3px;
    cursor: pointer;
    position: relative;
    font-weight: 600;
    transition: var(--transition);
}

.reading-content .vocab-highlight:hover {
    background: var(--primary);
    color: white;
}

.reading-content .vocab-tooltip {
    display: none;
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--dark);
    color: white;
    padding: 6px 12px;
    border-radius: 6px;
    font-size: 12px;
    font-weight: normal;
    white-space: nowrap;
    z-index: 10;
    margin-bottom: 4px;
}

.reading-content .vocab-highlight:hover .vocab-tooltip {
    display: block;
}

.reading-vocab-list {
    margin-top: 20px;
    padding-top: 16px;
    border-top: 2px solid var(--gray-light);
}

.reading-vocab-list h4 {
    color: var(--primary-dark);
    margin-bottom: 12px;
    font-size: 16px;
}

.vocab-tag {
    display: inline-block;
    margin: 4px;
    padding: 4px 10px;
    background: var(--primary-light);
    color: var(--primary);
    border-radius: 20px;
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition);
}

.vocab-tag:hover {
    background: var(--primary);
    color: white;
}

/* ===== 错题本 ===== */
.wrong-book-stats {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.wrong-stat-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 20px;
    text-align: center;
}

.wrong-stat-card .stat-icon {
    font-size: 32px;
    margin-bottom: 8px;
}

.wrong-stat-card .stat-num {
    font-size: 28px;
    font-weight: 700;
    color: var(--danger);
}

.wrong-stat-card .stat-label {
    font-size: 13px;
    color: var(--gray);
    margin-top: 4px;
}

.wrong-question-item {
    background: var(--card-bg);
    border-radius: var(--radius-sm);
    padding: 16px;
    margin-bottom: 12px;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--danger);
}

.wrong-question-item .wq-module {
    font-size: 12px;
    color: var(--gray);
    margin-bottom: 8px;
}

.wrong-question-item .wq-question {
    font-size: 15px;
    color: var(--dark);
    margin-bottom: 8px;
}

.wrong-question-item .wq-answer {
    display: flex;
    gap: 20px;
    font-size: 13px;
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid var(--gray-light);
}

.wrong-question-item .wq-your {
    color: var(--danger);
}

.wrong-question-item .wq-correct {
    color: var(--success);
}

/* ===== 仪表盘 ===== */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 20px;
}

.dashboard-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
    text-align: center;
    transition: var(--transition);
}

.dashboard-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}

.dashboard-card .dc-icon {
    font-size: 40px;
    margin-bottom: 12px;
}

.dashboard-card .dc-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 8px;
}

.dashboard-card .dc-value {
    font-size: 32px;
    font-weight: 700;
    color: var(--primary);
}

.dashboard-card .dc-subtitle {
    font-size: 13px;
    color: var(--gray);
    margin-top: 4px;
}

.progress-ring {
    width: 80px;
    height: 80px;
    margin: 0 auto 12px;
    position: relative;
}

.progress-ring svg {
    transform: rotate(-90deg);
}

.progress-ring circle {
    fill: none;
    stroke-width: 8;
}

.progress-ring .ring-bg {
    stroke: var(--gray-light);
}

.progress-ring .ring-fg {
    stroke: var(--primary);
    stroke-linecap: round;
    transition: stroke-dashoffset 0.5s ease;
}

.progress-ring .ring-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 16px;
    font-weight: 700;
    color: var(--primary);
}

/* ===== 弹窗 ===== */
.modal-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.5);
    z-index: 1000;
    justify-content: center;
    align-items: center;
}

.modal-overlay.show {
    display: flex;
}

.modal {
    background: var(--card-bg);
    border-radius: var(--radius);
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    position: relative;
    padding: 24px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.3);
}

.image-modal {
    max-width: 400px;
    text-align: center;
}

.modal-close {
    position: absolute;
    top: 12px;
    right: 12px;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--gray);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.modal-close:hover {
    background: var(--gray-light);
    color: var(--dark);
}

.modal-content h2 {
    color: var(--dark);
    margin-bottom: 16px;
}

.modal-content p {
    margin-bottom: 12px;
    line-height: 1.8;
}

/* ===== Toast 通知 ===== */
.toast-container {
    position: fixed;
    top: 80px;
    right: 24px;
    z-index: 2000;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.toast {
    background: var(--dark);
    color: white;
    padding: 12px 20px;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-hover);
    font-size: 14px;
    display: flex;
    align-items: center;
    gap: 8px;
    animation: slideIn 0.3s ease;
    min-width: 200px;
}

.toast.success { background: var(--success); }
.toast.error { background: var(--danger); }
.toast.warning { background: var(--warning); color: var(--dark); }
.toast.info { background: var(--info); }

/* ===== 章节选择器 ===== */
.chapter-selector {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.chapter-select {
    padding: 8px 12px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 14px;
    cursor: pointer;
    outline: none;
    background: white;
}

.chapter-select:focus {
    border-color: var(--primary);
}

/* ===== 动画 ===== */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

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

/* ===== 空状态 ===== */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--gray);
}

.empty-state .empty-icon {
    font-size: 64px;
    margin-bottom: 16px;
    opacity: 0.5;
}

.empty-state .empty-text {
    font-size: 16px;
    margin-bottom: 20px;
}

/* ===== app.js 补充样式 ===== */

/* Modal/Toast 修复 */
.modal-overlay.active { display: flex; }
.toast-show { opacity: 1 !important; transform: translateX(0) !important; }
.toast { opacity: 0; transform: translateX(100%); transition: all 0.3s ease; }
.toast-success, .toast.toast-success { background: var(--success); }
.toast-error, .toast.toast-error { background: var(--danger); }
.toast-warning, .toast.toast-warning { background: var(--warning); color: var(--dark); }
.toast-info, .toast.toast-info { background: var(--info); }

/* 模块头部/底部 */
.module-header {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
    margin-bottom: 20px;
}
.module-header h2 {
    font-size: 22px;
    font-weight: 700;
    color: var(--dark);
    flex: 1;
}
.module-footer {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 2px solid var(--gray-light);
    flex-wrap: wrap;
}

/* 按钮 */
.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}
.btn-outline:hover {
    background: var(--primary);
    color: white;
}
.btn-icon {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 18px;
    padding: 4px 8px;
    border-radius: 6px;
    transition: var(--transition);
}
.btn-icon:hover {
    background: var(--primary-light);
}

/* 章节卡片补充 */
.chapter-card .chapter-num {
    font-size: 28px;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 4px;
}
.chapter-card .chapter-label {
    font-size: 13px;
    color: var(--gray);
}
.chapter-card.completed::before { background: var(--success); }
.chapter-card.has-wrong::before { background: var(--danger); }
.chapter-card.has-wrong .chapter-num { color: var(--danger); }

/* 徽章 */
.badge {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
    margin-top: 4px;
}
.badge-success { background: var(--success); color: white; }
.badge-danger { background: var(--danger); color: white; }
.badge-info { background: var(--info); color: white; }
.badge-warning { background: var(--warning); color: var(--dark); }

/* 词汇学习 */
.word-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}
.word-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 20px;
    transition: var(--transition);
    border-left: 4px solid var(--primary);
}
.word-card:hover {
    box-shadow: var(--shadow-hover);
}
.word-card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}
.word-main {
    flex: 1;
}
.word-text {
    font-size: 22px;
    font-weight: 700;
    color: var(--dark);
    display: block;
}
.word-phonetic {
    font-size: 14px;
    color: var(--gray);
    font-style: italic;
    display: block;
    margin-top: 2px;
}
.word-pos {
    font-size: 12px;
    color: var(--primary);
    background: var(--primary-light);
    padding: 2px 8px;
    border-radius: 10px;
    display: inline-block;
    margin-top: 4px;
}
.word-actions {
    display: flex;
    gap: 4px;
}
.word-meaning {
    font-size: 16px;
    color: var(--text);
    margin-bottom: 8px;
    font-weight: 500;
}
.word-synonyms {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}
.syn-label {
    font-weight: 600;
    color: var(--gray);
}
.syn-tag {
    display: inline-block;
    padding: 2px 8px;
    background: var(--gray-light);
    border-radius: 10px;
    margin: 2px;
    font-size: 12px;
}
.word-example {
    background: var(--light);
    border-radius: var(--radius-sm);
    padding: 12px 16px;
    margin: 8px 0;
    border-left: 3px solid var(--secondary);
}
.ex-en {
    font-size: 14px;
    color: var(--dark);
    font-style: italic;
    margin-bottom: 4px;
}
.ex-cn {
    font-size: 13px;
    color: var(--gray);
}
.word-image-preview {
    margin-top: 12px;
    text-align: center;
}
.word-image-preview img {
    max-width: 200px;
    width: 100%;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
}
.word-image-preview img:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-hover);
}

/* 图片查看器 */
.image-viewer h3 {
    color: var(--dark);
    margin-bottom: 12px;
}
.image-viewer img {
    max-width: 100%;
    border-radius: var(--radius-sm);
}

/* 练习页面 */
.practice-progress {
    display: flex;
    justify-content: space-between;
    margin-bottom: 16px;
    font-size: 14px;
    color: var(--gray);
    font-weight: 600;
}
.practice-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 30px;
    max-width: 700px;
    margin: 0 auto;
}
.practice-question {
    text-align: center;
}
.practice-word {
    font-size: 32px;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 8px;
}
.practice-phonetic {
    font-size: 16px;
    color: var(--gray);
    font-style: italic;
    margin-bottom: 4px;
}
.practice-pos {
    font-size: 13px;
    color: var(--primary);
    background: var(--primary-light);
    padding: 2px 10px;
    border-radius: 10px;
    display: inline-block;
    margin-bottom: 16px;
}
.practice-hint {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 16px;
}
.practice-instruction {
    font-size: 16px;
    color: var(--dark);
    font-weight: 600;
    margin-bottom: 12px;
}
.practice-sentence {
    font-size: 18px;
    color: var(--dark);
    line-height: 1.8;
    margin-bottom: 16px;
    padding: 16px;
    background: var(--light);
    border-radius: var(--radius-sm);
}
.practice-sentence .blank {
    display: inline-block;
    min-width: 80px;
    border-bottom: 2px solid var(--primary);
    margin: 0 4px;
}
.practice-input {
    width: 100%;
    max-width: 400px;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 16px;
    outline: none;
    transition: var(--transition);
    text-align: center;
}
.practice-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(74, 108, 247, 0.1);
}
.practice-actions {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-top: 16px;
}
.practice-feedback {
    margin-top: 16px;
}
.feedback-correct {
    background: rgba(40, 167, 69, 0.1);
    border: 1px solid var(--success);
    color: var(--success);
    padding: 12px;
    border-radius: var(--radius-sm);
    font-weight: 600;
}
.feedback-wrong {
    background: rgba(220, 53, 69, 0.1);
    border: 1px solid var(--danger);
    color: var(--danger);
    padding: 12px;
    border-radius: var(--radius-sm);
    font-weight: 600;
}
.practice-options {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 16px;
}
.practice-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 20px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    text-align: left;
}
.practice-option:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}
.practice-option.selected {
    border-color: var(--primary);
    background: var(--primary-light);
}
.option-letter {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--gray-light);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 14px;
    flex-shrink: 0;
}
.practice-option.selected .option-letter {
    background: var(--primary);
    color: white;
}
.option-text {
    flex: 1;
    font-size: 15px;
}

/* 练习结果 */
.result-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 30px;
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}
.result-score {
    font-size: 56px;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 16px;
}
.result-detail p {
    font-size: 15px;
    margin-bottom: 8px;
    color: var(--text);
}
.text-success { color: var(--success); font-weight: 700; }
.text-danger { color: var(--danger); font-weight: 700; }
.wrong-review {
    margin: 20px 0;
    text-align: left;
}
.wrong-review h3 {
    font-size: 16px;
    color: var(--danger);
    margin-bottom: 12px;
}
.wrong-item {
    background: var(--light);
    border-radius: var(--radius-sm);
    padding: 12px 16px;
    margin-bottom: 10px;
    border-left: 3px solid var(--danger);
}
.wrong-q {
    font-size: 15px;
    color: var(--dark);
    font-weight: 600;
    margin-bottom: 4px;
}
.wrong-a {
    font-size: 13px;
    color: var(--danger);
}
.wrong-correct {
    font-size: 13px;
    color: var(--success);
    margin-top: 2px;
}
.result-actions {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-top: 20px;
}

/* 语法行 */
.grammar-line {
    font-size: 15px;
    line-height: 2;
    color: var(--text);
    margin-bottom: 12px;
    padding: 8px 0;
    border-bottom: 1px dashed var(--gray-light);
}

/* 应用文 */
.section-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--primary-dark);
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 2px solid var(--primary-light);
}
.writing-sentence {
    background: linear-gradient(135deg, #fff9e6 0%, #fff3d4 100%);
    border-left: 4px solid var(--secondary);
    padding: 16px;
    margin: 10px 0;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.ws-en {
    font-size: 15px;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 6px;
}
.ws-cn {
    font-size: 13px;
    color: var(--text-secondary);
}
.writing-section {
    margin-bottom: 24px;
}

/* 搜索栏 */
.search-bar {
    display: flex;
    gap: 10px;
    margin-bottom: 16px;
}
.search-bar input {
    flex: 1;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    outline: none;
    transition: var(--transition);
}
.search-bar input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(74, 108, 247, 0.1);
}
.reading-filters {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-bottom: 20px;
}
.filter-tag {
    padding: 6px 14px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 20px;
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition);
}
.filter-tag:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* 文章列表 */
.article-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 16px;
}
.article-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 20px;
    cursor: pointer;
    transition: var(--transition);
    border-top: 4px solid var(--primary);
}
.article-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}
.article-title {
    font-size: 17px;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 4px;
}
.article-title-cn {
    font-size: 14px;
    color: var(--gray);
    margin-bottom: 8px;
}
.article-meta {
    display: flex;
    gap: 8px;
}
.tag {
    display: inline-block;
    padding: 2px 8px;
    background: var(--primary-light);
    color: var(--primary);
    border-radius: 10px;
    font-size: 12px;
}

/* 文章正文 */
.article-content {
    font-size: 16px;
    line-height: 2.2;
    color: var(--text);
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 30px;
    margin-bottom: 20px;
}
.article-content .vocab-highlight {
    background: var(--primary-light);
    color: var(--primary);
    padding: 1px 4px;
    border-radius: 3px;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
}
.article-content .vocab-highlight:hover {
    background: var(--primary);
    color: white;
}

/* 文章词汇表 */
.article-vocab {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
}
.article-vocab h3 {
    font-size: 18px;
    color: var(--primary-dark);
    margin-bottom: 16px;
}
.vocab-table {
    display: grid;
    gap: 8px;
}
.vocab-row {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 8px 12px;
    background: var(--light);
    border-radius: var(--radius-sm);
    font-size: 14px;
}
.vocab-row .vw {
    font-weight: 700;
    color: var(--dark);
    min-width: 120px;
}
.vocab-row .vp {
    color: var(--gray);
    font-style: italic;
    min-width: 100px;
}
.vocab-row .vm {
    flex: 1;
    color: var(--text);
}

/* 错题本 */
.wrong-book-stats {
    margin-bottom: 16px;
}
.wrong-book-stats p {
    font-size: 14px;
    color: var(--gray);
}
.chapter-card.has-wrong {
    border-color: var(--danger);
}
.wrong-chapter-detail {
    margin-top: 20px;
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
}
.wrong-chapter-detail h3 {
    font-size: 18px;
    color: var(--dark);
    margin-bottom: 16px;
}
.wrong-module-section {
    margin-bottom: 20px;
}
.wrong-module-section h4 {
    font-size: 15px;
    color: var(--primary);
    margin-bottom: 10px;
    padding-bottom: 6px;
    border-bottom: 1px solid var(--gray-light);
}
.wrong-item {
    display: flex;
    flex-direction: column;
    gap: 4px;
}
.wrong-item button {
    align-self: flex-start;
    margin-top: 4px;
}

/* 仪表盘 */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 16px;
    margin-bottom: 30px;
}
.stat-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
    display: flex;
    align-items: center;
    gap: 16px;
    transition: var(--transition);
}
.stat-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}
.stat-blue { border-left: 4px solid var(--primary); }
.stat-green { border-left: 4px solid var(--success); }
.stat-orange { border-left: 4px solid var(--secondary); }
.stat-red { border-left: 4px solid var(--danger); }
.stat-icon {
    font-size: 36px;
}
.stat-info {
    flex: 1;
}
.stat-value {
    font-size: 24px;
    font-weight: 700;
    color: var(--dark);
}
.stat-label {
    font-size: 13px;
    color: var(--gray);
}
.dashboard-section {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
    margin-bottom: 20px;
}
.dashboard-section h3 {
    font-size: 18px;
    color: var(--dark);
    margin-bottom: 16px;
}
.module-progress-item {
    margin-bottom: 16px;
}
.mp-header {
    display: flex;
    justify-content: space-between;
    font-size: 14px;
    margin-bottom: 6px;
}
.mp-header span:first-child {
    font-weight: 600;
    color: var(--dark);
}
.mp-header span:last-child {
    color: var(--gray);
}
.mp-bar {
    height: 8px;
    background: var(--gray-light);
    border-radius: 4px;
    overflow: hidden;
}
.mp-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--primary-dark));
    border-radius: 4px;
    transition: width 0.5s ease;
}
.quick-links {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: 12px;
}
.quick-link {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 16px;
    background: var(--light);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
    text-align: center;
}
.quick-link:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

/* 空状态补充 */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--gray);
}
.empty-state p {
    font-size: 16px;
}

/* ===== 用户信息 ===== */
.user-info {
    display: flex;
    align-items: center;
    gap: 10px;
    color: white;
}
.user-name {
    font-size: 13px;
    font-weight: 600;
    white-space: nowrap;
}
.btn-outline-light {
    background: rgba(255,255,255,0.2);
    color: white;
    border: 1px solid rgba(255,255,255,0.5);
}
.btn-outline-light:hover {
    background: rgba(255,255,255,0.3);
    color: white;
}

/* ===== 认证弹窗 ===== */
.auth-modal {
    max-width: 400px;
    padding: 0;
    overflow: hidden;
}
.auth-tabs {
    display: flex;
    border-bottom: 1px solid var(--border);
}
.auth-tab {
    flex: 1;
    padding: 16px;
    text-align: center;
    cursor: pointer;
    font-weight: 600;
    color: var(--gray);
    transition: var(--transition);
    border-bottom: 2px solid transparent;
}
.auth-tab.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}
.auth-tab:hover {
    background: var(--light);
}
.auth-form {
    padding: 24px;
}
.form-group {
    margin-bottom: 16px;
}
.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 6px;
}
.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    outline: none;
    transition: var(--transition);
}
.form-group input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(74, 108, 247, 0.1);
}
.btn-block {
    width: 100%;
    justify-content: center;
}
.auth-hint {
    text-align: center;
    margin-top: 16px;
    font-size: 13px;
    color: var(--gray);
}
.auth-hint a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
}
.auth-hint a:hover {
    text-decoration: underline;
}

/* ===== 同步状态 ===== */
.sync-status {
    position: fixed;
    top: 80px;
    left: 50%;
    transform: translateX(-50%) translateY(-100px);
    background: var(--dark);
    color: white;
    padding: 10px 20px;
    border-radius: 20px;
    font-size: 13px;
    display: flex;
    align-items: center;
    gap: 8px;
    z-index: 2000;
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
}
.sync-status.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}
.sync-icon {
    font-size: 16px;
    animation: spin 1.5s linear infinite;
}
@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .menu-toggle {
        display: flex;
    }

    .sidebar {
        position: fixed;
        left: 0;
        top: var(--header-height);
        bottom: 0;
        transform: translateX(-100%);
        z-index: 99;
        box-shadow: 2px 0 16px rgba(0,0,0,0.15);
    }

    .sidebar.open {
        transform: translateX(0);
    }

    .app-title {
        font-size: 16px;
    }

    .progress-bar-container {
        width: 120px;
    }

    .content {
        padding: 16px;
    }

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

    .question-text {
        font-size: 16px;
    }

    .article-list {
        grid-template-columns: 1fr;
    }

    .practice-word {
        font-size: 24px;
    }

    .practice-card {
        padding: 16px;
    }

    .article-content {
        padding: 16px;
        font-size: 14px;
    }

    .word-card {
        padding: 14px;
    }

    .word-text {
        font-size: 18px;
    }

    .module-header h2 {
        font-size: 18px;
    }

    .quick-links {
        grid-template-columns: 1fr 1fr;
    }

    .stat-card {
        padding: 16px;
    }

    .stat-value {
        font-size: 20px;
    }

    .vocab-row {
        flex-wrap: wrap;
    }

    .vocab-row .vw, .vocab-row .vp {
        min-width: auto;
    }
}

/* ===== PWA 安装横幅 ===== */
.pwa-install-banner {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 1000;
    animation: pwaSlideUp 0.3s ease;
}

@keyframes pwaSlideUp {
    from {
        opacity: 0;
        transform: translateX(-50%) translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
}

.pwa-banner-content {
    display: flex;
    align-items: center;
    gap: 12px;
    background: white;
    padding: 12px 16px;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
    min-width: 280px;
    max-width: 90vw;
}

.pwa-banner-icon {
    font-size: 28px;
    flex-shrink: 0;
}

.pwa-banner-text {
    flex: 1;
    min-width: 0;
}

.pwa-banner-title {
    font-weight: 600;
    font-size: 14px;
    color: var(--dark);
}

.pwa-banner-desc {
    font-size: 12px;
    color: var(--gray);
    margin-top: 2px;
}

.pwa-banner-close {
    background: none;
    border: none;
    font-size: 20px;
    color: #ccc;
    cursor: pointer;
    padding: 0 4px;
    flex-shrink: 0;
}

.pwa-banner-close:hover {
    color: var(--dark);
}