/* ===== 全局变量 ===== */
:root {
    --primary: #4A6CF7;
    --primary-dark: #3B5AE0;
    --primary-light: #E8EEFF;
    --success: #22C55E;
    --danger: #EF4444;
    --warning: #F59E0B;
    --bg: #F5F7FB;
    --card-bg: #FFFFFF;
    --text: #1A2332;
    --text-secondary: #64748B;
    --border: #E2E8F0;
    --sidebar-bg: #1E293B;
    --sidebar-active: #4A6CF7;
    --shadow: 0 2px 8px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
    --radius: 12px;
    --radius-sm: 8px;
    --sidebar-w: 240px;
}

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

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

#app {
    display: flex;
    height: 100vh;
}

/* ===== 侧边栏 ===== */
.sidebar {
    width: var(--sidebar-w);
    background: var(--sidebar-bg);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 22px 20px;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}

.logo-icon {
    width: 36px;
    height: 36px;
    background: var(--primary);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 18px;
    font-weight: 700;
    flex-shrink: 0;
}

.logo-text {
    color: #fff;
    font-size: 16px;
    font-weight: 600;
    white-space: nowrap;
}

.nav-menu {
    list-style: none;
    padding: 12px 8px;
    flex: 1;
    overflow-y: auto;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    color: #94A3B8;
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: all 0.2s;
    margin-bottom: 2px;
    font-size: 14px;
}

.nav-item:hover {
    background: rgba(255,255,255,0.05);
    color: #E2E8F0;
}

.nav-item.active {
    background: var(--sidebar-active);
    color: #fff;
}

.nav-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

.sidebar-footer {
    padding: 16px 20px;
    border-top: 1px solid rgba(255,255,255,0.08);
}

.streak-badge {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.streak-number {
    font-size: 28px;
    font-weight: 700;
    color: var(--warning);
}

.streak-label {
    font-size: 11px;
    color: #64748B;
}

/* ===== 主内容区 ===== */
.main-content {
    flex: 1;
    overflow-y: auto;
    padding: 32px 40px;
}

.page {
    display: none;
    animation: fadeIn 0.3s ease;
}

.page.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.page-header {
    margin-bottom: 28px;
}

.page-header h1 {
    font-size: 26px;
    font-weight: 700;
    margin-bottom: 6px;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 14px;
}

/* ===== 统计卡片 ===== */
.stat-cards {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-bottom: 32px;
}

.stat-card {
    background: var(--card-bg);
    padding: 20px 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    text-align: center;
}

.stat-value {
    font-size: 32px;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 4px;
}

.stat-label {
    font-size: 13px;
    color: var(--text-secondary);
}

/* ===== 模块卡片网格 ===== */
.dashboard-modules h2 {
    font-size: 18px;
    margin-bottom: 16px;
}

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

.module-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 16px;
    cursor: pointer;
    transition: all 0.2s;
    border: 2px solid transparent;
}

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

.module-icon {
    width: 48px;
    height: 48px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 22px;
    font-weight: 700;
    color: #fff;
    flex-shrink: 0;
}

.module-icon.speed { background: linear-gradient(135deg, #4A6CF7, #667DB6); }
.module-icon.chart { background: linear-gradient(135deg, #22C55E, #16A34A); }
.module-icon.exam { background: linear-gradient(135deg, #F59E0B, #D97706); }
.module-icon.wrong { background: linear-gradient(135deg, #EF4444, #DC2626); }

.module-info {
    flex: 1;
}

.module-info h3 {
    font-size: 16px;
    margin-bottom: 4px;
}

.module-info p {
    font-size: 13px;
    color: var(--text-secondary);
}

.module-arrow {
    font-size: 24px;
    color: var(--text-secondary);
}

/* ===== 技巧选择器 ===== */
.technique-selector {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
    flex-wrap: wrap;
}

.technique-btn {
    padding: 8px 18px;
    border: 1px solid var(--border);
    background: var(--card-bg);
    border-radius: 20px;
    cursor: pointer;
    font-size: 14px;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.technique-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.technique-btn.active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

/* ===== 训练区域 ===== */
.train-area {
    max-width: 760px;
}

/* ===== 题目卡片 ===== */
.question-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 28px 32px;
    box-shadow: var(--shadow);
    margin-bottom: 20px;
}

.question-tag {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 600;
    margin-bottom: 16px;
}

.question-tag.first-digit { background: #E8EEFF; color: #4A6CF7; }
.question-tag.last-digit { background: #E8F9EF; color: #22C55E; }
.question-tag.feature-number { background: #FFF4E6; color: #F59E0B; }
.question-tag.significant { background: #FFE8E8; color: #EF4444; }
.question-tag.compare { background: #F0E8FF; color: #8B5CF6; }
.question-tag.bar { background: #E8EEFF; color: #4A6CF7; }
.question-tag.line { background: #E8F9EF; color: #22C55E; }
.question-tag.pie { background: #FFF4E6; color: #F59E0B; }
.question-tag.table { background: #F0E8FF; color: #8B5CF6; }

.question-text {
    font-size: 18px;
    line-height: 1.6;
    margin-bottom: 20px;
    font-weight: 500;
}

.question-hint {
    font-size: 13px;
    color: var(--text-secondary);
    background: var(--primary-light);
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    margin-bottom: 20px;
    border-left: 3px solid var(--primary);
}

/* ===== 答案输入与选项 ===== */
.answer-section {
    margin-top: 20px;
}

.answer-label {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 8px;
    display: block;
}

.answer-input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 16px;
    outline: none;
    transition: border-color 0.2s;
}

.answer-input:focus {
    border-color: var(--primary);
}

.options-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.option-btn {
    padding: 12px 16px;
    border: 2px solid var(--border);
    background: var(--card-bg);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 15px;
    text-align: left;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 8px;
}

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

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

.option-btn.correct {
    border-color: var(--success);
    background: #E8F9EF;
}

.option-btn.wrong {
    border-color: var(--danger);
    background: #FFE8E8;
}

.option-label {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    border: 2px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 13px;
    font-weight: 600;
    flex-shrink: 0;
    color: var(--text-secondary);
}

.option-btn.selected .option-label {
    border-color: var(--primary);
    background: var(--primary);
    color: #fff;
}

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

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

/* ===== 按钮组 ===== */
.btn-group {
    display: flex;
    gap: 12px;
    margin-top: 24px;
}

.btn {
    padding: 12px 28px;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

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

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

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

.btn-secondary:hover {
    background: #E2E8F0;
}

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

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ===== 反馈区 ===== */
.feedback {
    margin-top: 20px;
    padding: 16px 20px;
    border-radius: var(--radius-sm);
    display: none;
    font-size: 14px;
    line-height: 1.6;
}

.feedback.show {
    display: block;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(-8px); }
    to { opacity: 1; transform: translateY(0); }
}

.feedback.correct {
    background: #E8F9EF;
    border-left: 4px solid var(--success);
}

.feedback.wrong {
    background: #FFE8E8;
    border-left: 4px solid var(--danger);
}

.feedback-title {
    font-weight: 700;
    margin-bottom: 8px;
}

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

.feedback-answer {
    margin-top: 6px;
}

.feedback-tip {
    margin-top: 8px;
    color: var(--text-secondary);
    font-size: 13px;
}

/* ===== 图表容器 ===== */
.chart-container {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
    margin-bottom: 20px;
}

.chart-title {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
    text-align: center;
    color: var(--text);
}

.chart-canvas-wrap {
    display: flex;
    justify-content: center;
    margin-bottom: 16px;
}

canvas {
    max-width: 100%;
}

/* ===== 数据表格 ===== */
.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 14px;
    margin-top: 8px;
}

.data-table th,
.data-table td {
    padding: 10px 14px;
    text-align: center;
    border: 1px solid var(--border);
}

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

.data-table tbody tr:nth-child(even) {
    background: #F8FAFC;
}

/* ===== 计时器 ===== */
.timer-bar {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
    background: var(--card-bg);
    padding: 12px 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.timer-display {
    font-size: 24px;
    font-weight: 700;
    color: var(--primary);
    font-variant-numeric: tabular-nums;
}

.timer-label {
    font-size: 14px;
    color: var(--text-secondary);
}

.timer-progress {
    flex: 1;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
    margin-left: 12px;
}

.timer-progress-fill {
    height: 100%;
    background: var(--primary);
    border-radius: 3px;
    transition: width 1s linear;
}

.timer-progress-fill.warning {
    background: var(--warning);
}

.timer-progress-fill.danger {
    background: var(--danger);
}

/* ===== 材料展示 ===== */
.material-block {
    background: #F8FAFC;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px 24px;
    margin-bottom: 20px;
    font-size: 14px;
    line-height: 1.8;
}

.material-block h4 {
    font-size: 15px;
    margin-bottom: 10px;
    color: var(--primary);
}

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

.empty-state-icon {
    font-size: 48px;
    margin-bottom: 16px;
    opacity: 0.3;
}

.empty-state-text {
    font-size: 15px;
}

.empty-state-hint {
    font-size: 13px;
    margin-top: 8px;
    color: var(--border);
}

/* ===== 统计图表 ===== */
.stats-section {
    margin-bottom: 32px;
}

.stats-section h3 {
    font-size: 16px;
    margin-bottom: 16px;
}

.stats-table {
    width: 100%;
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.stats-table table {
    width: 100%;
    border-collapse: collapse;
    font-size: 14px;
}

.stats-table th,
.stats-table td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.stats-table th {
    background: var(--primary-light);
    color: var(--primary);
    font-weight: 600;
    font-size: 13px;
}

.stats-table tbody tr:hover {
    background: #F8FAFC;
}

.progress-bar {
    width: 100px;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
    display: inline-block;
}

.progress-bar-fill {
    height: 100%;
    border-radius: 3px;
}

/* ===== 错题列表 ===== */
.wrong-item {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 20px 24px;
    box-shadow: var(--shadow);
    margin-bottom: 12px;
}

.wrong-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.wrong-item-text {
    font-size: 15px;
    margin-bottom: 10px;
    line-height: 1.6;
}

.wrong-item-answer {
    display: flex;
    gap: 20px;
    font-size: 13px;
    padding-top: 10px;
    border-top: 1px solid var(--border);
}

.wrong-item-answer .label {
    color: var(--text-secondary);
}

.wrong-item-answer .value {
    font-weight: 600;
}

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

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

/* ===== 响应式 ===== */
/* ===== 手写触发按钮 ===== */
.hw-trigger-btn {
    padding: 8px 16px;
    font-size: 14px;
    border: 1px solid var(--border);
    background: var(--card-bg);
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.hw-trigger-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-light);
}

/* ===== 手写遮罩层 ===== */
.hw-overlay {
    position: fixed;
    inset: 0;
    z-index: 9999;
    background: transparent;
    display: flex;
    flex-direction: column;
    overscroll-behavior: none;
    -webkit-overflow-scrolling: none;
}

.hw-toolbar {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 12px;
    background: rgba(30, 41, 59, 0.92);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    flex-shrink: 0;
    flex-wrap: nowrap;
    overflow-x: auto;
    scrollbar-width: none;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15);
    z-index: 2;
}

.hw-toolbar::-webkit-scrollbar {
    display: none;
}

.hw-tool-group {
    display: flex;
    align-items: center;
    gap: 4px;
    flex-shrink: 0;
}

.hw-btn {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 8px 12px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    color: #94A3B8;
    background: transparent;
    transition: all 0.15s;
    white-space: nowrap;
    min-height: 36px;
}

.hw-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #E2E8F0;
}

.hw-btn:active {
    transform: scale(0.95);
}

.hw-btn:disabled {
    opacity: 0.35;
    cursor: not-allowed;
}

.hw-btn:disabled:hover {
    background: transparent;
    color: #94A3B8;
}

.hw-btn-tool.active {
    background: var(--primary);
    color: #fff;
}

.hw-btn-close {
    background: var(--danger) !important;
    color: #fff !important;
    padding: 8px 16px;
}

.hw-btn-close:hover {
    background: #DC2626 !important;
    color: #fff !important;
}

/* 颜色选择器 */
.hw-color-picker {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 0 4px;
}

.hw-color-btn {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    border: 2px solid rgba(255, 255, 255, 0.3);
    cursor: pointer;
    transition: all 0.15s;
    padding: 0;
    flex-shrink: 0;
}

.hw-color-btn:active {
    transform: scale(0.9);
}

.hw-color-btn.active {
    border-color: #fff;
    box-shadow: 0 0 0 2px var(--primary);
    transform: scale(1.1);
}

/* 画布区域 */
.hw-canvas-wrap {
    flex: 1;
    position: relative;
    overflow: hidden;
}

.hw-canvas {
    display: block;
    position: absolute;
    top: 0;
    left: 0;
    cursor: crosshair;
    touch-action: none;
    -webkit-user-select: none;
    user-select: none;
    -webkit-touch-callout: none;
}

.hw-mode-badge {
    position: fixed;
    bottom: 16px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(30, 41, 59, 0.85);
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    color: #94A3B8;
    font-size: 12px;
    padding: 6px 16px;
    border-radius: 20px;
    pointer-events: none;
    z-index: 2;
    white-space: nowrap;
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .sidebar { width: 60px; }
    .logo-text, .nav-item span:not(.nav-icon), .sidebar-footer { display: none; }
    .main-content { padding: 20px; }
    .stat-cards { grid-template-columns: repeat(2, 1fr); }
    .module-grid { grid-template-columns: 1fr; }
    .options-grid { grid-template-columns: 1fr; }
    .hw-btn { padding: 8px 10px; min-height: 40px; }
    .hw-btn span { display: none; }
    .hw-color-btn { width: 28px; height: 28px; }
    .hw-toolbar { padding: 6px 8px; gap: 4px; }
    .hw-mode-badge { font-size: 11px; bottom: 10px; }
}