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

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --primary-light: #a5b4fc;
    --secondary-color: #8b5cf6;
    --accent-color: #06b6d4;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --bg-color: #0f172a;
    --bg-secondary: #1e293b;
    --card-bg: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-text-size-adjust: 100%;
    -webkit-tap-highlight-color: transparent;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
}

.header {
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #06b6d4 100%);
    color: white;
    padding: 56px 0;
    box-shadow: var(--shadow-lg), var(--shadow-glow);
    position: relative;
    overflow: hidden;
    z-index: 100;
}

.header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    opacity: 0.5;
    pointer-events: none;
    z-index: 1;
}

.title {
    font-size: 2.8rem;
    font-weight: 800;
    margin-bottom: 10px;
    text-align: center;
    letter-spacing: -0.02em;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.95;
    text-align: center;
    font-weight: 500;
    letter-spacing: 0.01em;
}

.main {
    padding: 40px 0;
}

.main .container {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 32px;
    align-items: start;
}

.sidebar {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg), 0 0 0 1px var(--border-color);
    position: sticky;
    top: 24px;
    overflow: hidden;
}

.sidebar-header {
    padding: 24px;
    border-bottom: 1px solid var(--border-color);
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1) 0%, rgba(139, 92, 246, 0.05) 100%);
}

.sidebar-header h3 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: 0.01em;
}

.category-nav {
    padding: 16px;
}

.category-item {
    display: flex;
    align-items: center;
    padding: 16px 18px;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    margin-bottom: 6px;
    border: 1px solid transparent;
    position: relative;
    -webkit-tap-highlight-color: transparent;
    -webkit-appearance: none;
    appearance: none;
    min-height: 56px;
}

.category-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 3px;
    height: 0;
    background: linear-gradient(180deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border-radius: 0 3px 3px 0;
    transition: height 0.3s ease;
}

.category-item:hover {
    background: rgba(99, 102, 241, 0.1);
    border-color: var(--border-color);
    transform: translateX(4px);
}

.category-item:hover::before {
    height: 50%;
}

.category-item.active {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.15) 0%, rgba(139, 92, 246, 0.1) 100%);
    border-color: rgba(99, 102, 241, 0.3);
    color: var(--text-primary);
    font-weight: 600;
}

.category-item.active::before {
    height: 70%;
}

.category-icon {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-right: 14px;
    font-size: 1.35rem;
    background: rgba(15, 23, 42, 0.5);
    transition: all 0.3s ease;
}

.category-item:hover .category-icon {
    transform: scale(1.1);
}

.category-item.active .category-icon {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.category-name {
    flex: 1;
    font-size: 0.97rem;
}

.category-count {
    font-size: 0.85rem;
    color: var(--text-secondary);
    background: rgba(15, 23, 42, 0.6);
    padding: 4px 12px;
    border-radius: 20px;
    font-weight: 600;
    border: 1px solid var(--border-color);
}

.category-item.active .category-count {
    background: white;
    color: var(--primary-color);
}

.content {
    min-height: 600px;
}

.content-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    flex-wrap: wrap;
    gap: 16px;
}

.breadcrumb {
    display: flex;
    align-items: center;
    gap: 8px;
}

.breadcrumb-item {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.stats {
    display: flex;
    gap: 16px;
}

.stat-item {
    background: var(--card-bg);
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    font-weight: 500;
    color: var(--text-secondary);
    box-shadow: var(--shadow-sm);
}

.questions-container,
.short-answer-container {
    display: grid;
    gap: 20px;
}

.question-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-md);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
}

.question-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--secondary-color) 50%, var(--accent-color) 100%);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.question-card:hover {
    box-shadow: var(--shadow-lg), 0 0 0 1px rgba(99, 102, 241, 0.2);
    transform: translateY(-4px);
}

.question-card:hover::before {
    opacity: 1;
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 12px;
}

.question-number {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 8px 20px;
    border-radius: 24px;
    font-weight: 700;
    font-size: 0.9rem;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.question-category {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: linear-gradient(135deg, rgba(6, 182, 212, 0.15) 0%, rgba(139, 92, 246, 0.1) 100%);
    color: var(--text-primary);
    padding: 8px 18px;
    border-radius: 24px;
    font-size: 0.85rem;
    font-weight: 600;
    border: 1px solid rgba(6, 182, 212, 0.3);
}

.question-text {
    font-size: 1.2rem;
    color: var(--text-primary);
    line-height: 1.8;
    margin-bottom: 24px;
    font-weight: 500;
}

.question-answer-toggle {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1) 0%, rgba(139, 92, 246, 0.05) 100%);
    border: 1px solid rgba(99, 102, 241, 0.3);
    color: var(--primary-light);
    padding: 12px 24px;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 600;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.question-answer-toggle:hover {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    border-color: transparent;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.4);
}

.question-answer {
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
    display: none;
}

.question-answer.show {
    display: block;
    animation: fadeIn 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.answer-label {
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 16px;
    font-size: 1.05rem;
    display: flex;
    align-items: center;
    gap: 10px;
}

.answer-content {
    color: var(--text-secondary);
    line-height: 1.8;
    padding: 20px 24px;
    background: linear-gradient(135deg, rgba(15, 23, 42, 0.6) 0%, rgba(30, 41, 59, 0.8) 100%);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--accent-color);
    border: 1px solid var(--border-color);
    position: relative;
}

.answer-content::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(6, 182, 212, 0.05) 0%, rgba(139, 92, 246, 0.03) 100%);
    border-radius: var(--radius-md);
    pointer-events: none;
}

.footer {
    background: var(--card-bg);
    padding: 24px 0;
    margin-top: 60px;
    border-top: 1px solid var(--border-color);
}

.footer p {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.empty-state {
    text-align: center;
    padding: 80px 20px;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 16px;
}

.empty-state-text {
    font-size: 1.1rem;
}

@media (max-width: 1024px) {
    .main .container {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .sidebar {
        position: static;
        max-height: 280px;
        overflow-y: auto;
        -webkit-overflow-scrolling: touch;
        order: 0;
    }

    .content {
        order: 1;
    }

    .title {
        font-size: 2rem;
    }

    .content-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }

    .stats {
        width: 100%;
        flex-wrap: wrap;
        gap: 8px;
    }

    .stat-item {
        flex: 1;
        min-width: calc(50% - 8px);
        text-align: center;
    }
}

.page-nav {
    background: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
}

.page-nav .container {
    display: flex;
    justify-content: flex-start;
    gap: 0;
    padding: 8px 16px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
}

.page-nav .container::-webkit-scrollbar {
    display: none;
}

.page-tab {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 14px 28px;
    background: transparent;
    border: none;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border-radius: var(--radius-md);
    margin: 0 4px;
    position: relative;
    -webkit-tap-highlight-color: transparent;
    -webkit-appearance: none;
    appearance: none;
    min-height: 52px;
}

.page-tab::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    border-radius: 3px 3px 0 0;
    transition: width 0.3s ease;
}

.page-tab:hover {
    color: var(--text-primary);
    background: rgba(99, 102, 241, 0.1);
}

.page-tab:hover::before {
    width: 60%;
}

.page-tab.active {
    color: white;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
}

.page-tab.active::before {
    width: 80%;
}

.tab-icon {
    font-size: 1.4rem;
}

.tab-text {
    font-weight: 600;
    letter-spacing: 0.01em;
}

.notes-container {
    display: grid;
    gap: 20px;
}

.note-card {
    background: var(--card-bg);
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--primary-color);
}

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

.note-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background: linear-gradient(135deg, var(--primary-color) 0%, #1e40af 100%);
    color: white;
    border-radius: 50%;
    font-weight: 600;
    font-size: 0.85rem;
    margin-bottom: 12px;
}

.note-content {
    color: var(--text-primary);
    line-height: 1.8;
    font-size: 1rem;
}

@media (max-width: 1024px) {
    .main .container {
        grid-template-columns: 1fr;
    }

    .sidebar {
        position: static;
        max-height: 300px;
        overflow-y: auto;
        -webkit-overflow-scrolling: touch;
    }

    .title {
        font-size: 2rem;
    }

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

    .stats {
        width: 100%;
        flex-wrap: wrap;
    }

    .stat-item {
        flex: 1;
        min-width: calc(50% - 8px);
        text-align: center;
    }
}

@media (max-width: 768px) {
    .main .container {
        gap: 16px;
    }

    .sidebar {
        max-height: 240px;
        border-radius: 12px;
    }

    .sidebar-header {
        padding: 16px;
    }

    .category-nav {
        padding: 12px;
    }

    .category-item {
        padding: 12px 14px;
        min-height: 48px;
        margin-bottom: 4px;
    }

    .page-nav .container {
        padding: 8px 8px;
    }
    
    .page-tab {
        padding: 12px 14px;
        flex-shrink: 0;
        min-height: 48px;
        gap: 6px;
    }
    
    .tab-text {
        font-size: 0.85rem;
        display: none;
    }
    
    .page-tab.active .tab-text,
    .page-tab:hover .tab-text {
        display: inline;
    }
    
    .tab-icon {
        font-size: 1.4rem;
    }
    
    .generate-exam-btn,
    .print-exam-btn,
    .save-exam-btn,
    .add-question-btn,
    .remove-question-btn {
        padding: 14px 20px;
        font-size: 0.9rem;
        min-height: 48px;
        width: 100%;
        justify-content: center;
    }
    
    .form-group input,
    .form-group select,
    .form-group textarea {
        min-height: 48px;
        font-size: 16px;
        padding: 12px 16px;
    }
    
    .exam-info-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }
    
    .exam-info-label {
        margin-right: 0;
    }
    
    .exam-info-input {
        width: 100%;
    }
    
    .question-answer-toggle {
        width: 100%;
        justify-content: center;
        min-height: 48px;
    }
    
    .exam-answer-toggle {
        width: 100%;
        justify-content: center;
        min-height: 48px;
    }
}

@media (max-width: 640px) {
    .container {
        padding: 0 12px;
    }

    .header {
        padding: 24px 0;
    }

    .title {
        font-size: 1.4rem;
    }

    .subtitle {
        font-size: 0.9rem;
    }

    .question-card {
        padding: 16px;
        border-radius: 12px;
    }

    .question-text {
        font-size: 1rem;
        line-height: 1.6;
    }

    .question-number,
    .question-category {
        font-size: 0.8rem;
        padding: 6px 12px;
    }

    .page-tab {
        padding: 10px 12px;
        flex-shrink: 0;
        min-height: 44px;
    }

    .tab-text {
        font-size: 0.8rem;
    }
    
    .main {
        padding: 20px 0;
    }
    
    .sidebar {
        padding: 12px;
        border-radius: 12px;
    }
    
    .sidebar-header {
        padding: 16px;
    }
    
    .category-nav {
        padding: 12px;
    }
    
    .category-item {
        padding: 12px 14px;
        min-height: 48px;
        border-radius: 10px;
    }
    
    .category-icon {
        width: 36px;
        height: 36px;
        font-size: 1.1rem;
        margin-right: 10px;
    }
    
    .category-name {
        font-size: 0.9rem;
    }
    
    .category-count {
        font-size: 0.75rem;
        padding: 3px 10px;
    }
    
    .generate-exam-btn {
        width: 100%;
        justify-content: center;
    }
    
    .toolbar {
        flex-direction: column;
    }
    
    .search-box {
        width: 100%;
    }
    
    .toolbar .btn {
        width: 100%;
        justify-content: center;
    }
    
    .content-header {
        gap: 12px;
    }
    
    .stat-item {
        font-size: 0.85rem;
        padding: 8px 12px;
    }
}

.generate-exam-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--primary-color) 0%, #1e40af 100%);
    color: white;
    border: none;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.2s ease;
    box-shadow: var(--shadow-md);
}

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

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

.btn-icon {
    font-size: 1.2rem;
}

.btn-text {
    font-weight: 600;
}

.practical-exam-container {
    display: grid;
    gap: 24px;
}

.exam-info {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    border: 1px solid #bfdbfe;
    border-radius: var(--radius-md);
    padding: 24px;
    margin-bottom: 8px;
}

.exam-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.exam-stats {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
}

.exam-stat {
    background: white;
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    color: var(--text-primary);
    box-shadow: var(--shadow-sm);
    font-size: 0.95rem;
}

.exam-question-card {
    background: var(--card-bg);
    border-radius: var(--radius-md);
    padding: 32px;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    border: 2px solid var(--border-color);
}

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

.exam-question-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 12px;
}

.exam-question-number {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    padding: 8px 20px;
    border-radius: 20px;
    font-weight: 700;
    font-size: 1rem;
}

.exam-question-difficulty {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.exam-question-difficulty span {
    display: flex;
    align-items: center;
    gap: 6px;
}

.exam-question-category {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: #fef3c7;
    color: #92400e;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

.exam-question-text {
    font-size: 1.25rem;
    color: var(--text-primary);
    line-height: 1.8;
    margin-bottom: 24px;
    font-weight: 500;
}

.exam-answer-toggle {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--accent-color) 0%, #d97706 100%);
    border: none;
    color: white;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.2s ease;
    box-shadow: var(--shadow-md);
}

.exam-answer-toggle:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.exam-answer-toggle:active {
    transform: translateY(0);
}

.exam-question-answer {
    margin-top: 24px;
    padding-top: 24px;
    border-top: 2px solid var(--border-color);
    display: none;
}

.exam-question-answer.show {
    display: block;
    animation: fadeIn 0.3s ease;
}

.question-difficulty {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    background: #fef3c7;
    color: #92400e;
}

.login-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.login-overlay.hidden {
    display: none;
}

.login-modal {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 420px;
    margin: 24px;
    animation: slideIn 0.3s ease;
}

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

.login-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, #1e40af 100%);
    color: white;
    padding: 32px 24px;
    text-align: center;
    border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}

.login-header h2 {
    font-size: 1.5rem;
    font-weight: 700;
}

.login-content {
    padding: 32px 24px;
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
    font-size: 0.95rem;
}

.form-group input {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    transition: all 0.2s ease;
    -webkit-appearance: none;
    appearance: none;
    min-height: 48px;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.login-error {
    color: #dc2626;
    font-size: 0.9rem;
    margin-bottom: 20px;
    min-height: 24px;
    text-align: center;
}

.login-btn {
    width: 100%;
    padding: 16px;
    background: linear-gradient(135deg, var(--primary-color) 0%, #1e40af 100%);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: var(--shadow-md);
}

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

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

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    z-index: 10;
}

.header-title {
    flex: 1;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 16px;
    background: rgba(255, 255, 255, 0.15);
    padding: 14px 24px;
    border-radius: var(--radius-lg);
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    position: relative;
    z-index: 10;
}

.user-welcome {
    font-size: 1rem;
    font-weight: 500;
}

.user-welcome span {
    font-weight: 700;
}

.user-role {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.25) 0%, rgba(255, 255, 255, 0.15) 100%);
    padding: 6px 16px;
    border-radius: 24px;
    font-size: 0.85rem;
    font-weight: 600;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.logout-btn {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.2) 0%, rgba(255, 255, 255, 0.1) 100%);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.25);
    padding: 10px 20px;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.3s ease;
    position: relative;
    z-index: 20;
    -webkit-tap-highlight-color: transparent;
    -webkit-appearance: none;
    appearance: none;
}

.logout-btn:hover {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.3) 0%, rgba(255, 255, 255, 0.2) 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.admin-btn {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
}

.admin-btn:hover {
    background: linear-gradient(135deg, #059669 0%, #047857 100%);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(16, 185, 129, 0.4);
}

.tab-badge {
    font-size: 0.75rem;
    margin-left: 6px;
}

.page-tab.locked {
    opacity: 0.5;
    cursor: not-allowed;
}

.print-exam-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--accent-color) 0%, #0891b2 100%);
    color: white;
    border: none;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(6, 182, 212, 0.3);
}

.print-exam-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(6, 182, 212, 0.4);
}

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

.save-exam-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--success-color) 0%, #059669 100%);
    color: white;
    border: none;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
}

.save-exam-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.4);
}

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

.add-question-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
    border: none;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
}

.add-question-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(245, 158, 11, 0.4);
}

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

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

.remove-question-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, #f97316 0%, #ea580c 100%);
    color: white;
    border: none;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(249, 115, 22, 0.3);
}

.remove-question-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(249, 115, 22, 0.4);
}

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

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

.initial-exam-container {
    display: grid;
    gap: 24px;
}

.initial-exam-paper {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 40px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.exam-header {
    text-align: center;
    margin-bottom: 36px;
    padding-bottom: 24px;
    border-bottom: 2px solid var(--border-color);
}

.exam-title {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.exam-info-section {
    margin-bottom: 36px;
    padding: 24px;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.08) 0%, rgba(139, 92, 246, 0.04) 100%);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--radius-md);
}

.exam-info-row {
    display: flex;
    gap: 24px;
    margin-bottom: 20px;
}

.exam-info-row:last-child {
    margin-bottom: 0;
}

.exam-info-item {
    flex: 1;
    display: flex;
    align-items: center;
}

.exam-info-label {
    font-weight: 700;
    color: var(--text-primary);
    white-space: nowrap;
    margin-right: 12px;
}

.exam-info-input {
    flex: 1;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    background: rgba(15, 23, 42, 0.5);
    color: var(--text-primary);
    transition: all 0.3s ease;
    -webkit-appearance: none;
    appearance: none;
    min-height: 48px;
}

.exam-info-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
    background: rgba(15, 23, 42, 0.8);
}

.exam-questions-section {
    margin-bottom: 36px;
}

.section-title {
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 24px;
    padding-left: 16px;
    border-left: 4px solid var(--primary-color);
}

.exam-question-item {
    margin-bottom: 28px;
    padding: 24px;
    background: linear-gradient(135deg, rgba(30, 41, 59, 0.6) 0%, rgba(30, 41, 59, 0.4) 100%);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: all 0.3s ease;
}

.exam-question-item:hover {
    box-shadow: var(--shadow-md);
    border-color: rgba(99, 102, 241, 0.3);
}

.exam-question-item .question-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 18px;
}

.exam-question-item .question-number {
    font-size: 1.1rem;
    font-weight: 800;
    color: var(--primary-light);
}

.exam-question-item .question-category {
    font-size: 0.85rem;
    color: var(--text-secondary);
    background: rgba(99, 102, 241, 0.15);
    padding: 6px 14px;
    border-radius: 20px;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.exam-question-item .question-text {
    font-size: 1.1rem;
    color: var(--text-primary);
    line-height: 1.8;
    margin-bottom: 18px;
}

.answer-section {
    margin-bottom: 18px;
    padding: 20px;
    background: linear-gradient(135deg, rgba(6, 182, 212, 0.08) 0%, rgba(99, 102, 241, 0.04) 100%);
    border-left: 4px solid var(--accent-color);
    border-radius: var(--radius-sm);
}

.answer-label {
    font-weight: 800;
    color: var(--accent-color);
    margin-bottom: 10px;
    font-size: 1rem;
}

.answer-text {
    color: var(--text-primary);
    line-height: 1.8;
    font-size: 1rem;
}

.score-section {
    display: flex;
    align-items: center;
    gap: 12px;
    padding-top: 18px;
    border-top: 1px dashed var(--border-color);
}

.score-label {
    font-weight: 700;
    color: var(--text-primary);
}

.score-input {
    width: 100px;
    padding: 10px 12px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    text-align: center;
    background: rgba(15, 23, 42, 0.5);
    color: var(--text-primary);
    transition: all 0.3s ease;
    -webkit-appearance: none;
    appearance: none;
    min-height: 44px;
}

.score-input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(6, 182, 212, 0.2);
    background: rgba(15, 23, 42, 0.8);
}

.score-unit {
    color: var(--text-secondary);
    font-weight: 600;
}

.exam-footer {
    margin-top: 48px;
}

.signature-section {
    display: flex;
    justify-content: space-between;
    margin-bottom: 36px;
}

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

.signature-label {
    font-weight: 700;
    color: var(--text-primary);
    white-space: nowrap;
}

.signature-line {
    width: 220px;
    height: 1px;
    background: var(--text-secondary);
    border-bottom: 1px solid var(--text-secondary);
}

.exam-remark {
    margin-top: 36px;
}

.remark-label {
    font-weight: 700;
    color: var(--text-primary);
    display: block;
    margin-bottom: 12px;
}

.remark-textarea {
    width: 100%;
    min-height: 100px;
    padding: 14px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-family: inherit;
    background: rgba(15, 23, 42, 0.5);
    color: var(--text-primary);
    resize: vertical;
    transition: all 0.3s ease;
    -webkit-appearance: none;
    appearance: none;
}

.remark-textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
    background: rgba(15, 23, 42, 0.8);
}

@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }
    
    .header-title {
        text-align: center;
    }
    
    .user-info {
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .exam-info-row {
        flex-direction: column;
        gap: 16px;
    }
    
    .signature-section {
        flex-direction: column;
        gap: 24px;
    }
    
    .signature-line {
        width: 100%;
        max-width: 220px;
    }
    
    .initial-exam-paper {
        padding: 24px;
    }
    
    .exam-question-card {
        padding: 20px;
    }
    
    .exam-question-text {
        font-size: 1.1rem;
    }
    
    .exam-question-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }
    
    .exam-stats {
        flex-direction: column;
    }
    
    .exam-stat {
        width: 100%;
        text-align: center;
    }
    
    .exam-info {
        padding: 20px;
    }
    
    .exam-title {
        font-size: 1.25rem;
    }
    
    .exam-answer-toggle {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .title {
        font-size: 1.25rem;
    }
    
    .subtitle {
        font-size: 0.8rem;
    }
    
    .header {
        padding: 20px 0;
    }
    
    .page-tab {
        padding: 8px 10px;
        min-height: 40px;
    }
    
    .tab-icon {
        font-size: 1.3rem;
    }
    
    .tab-text {
        font-size: 0.75rem;
    }
    
    .question-card {
        padding: 14px;
    }
    
    .question-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }
    
    .exam-question-card {
        padding: 16px;
    }
    
    .exam-question-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }
    
    .login-modal {
        margin: 12px;
        max-width: 100%;
    }
    
    .login-content {
        padding: 20px 16px;
    }
    
    .login-header h2 {
        font-size: 1.3rem;
    }
    
    .user-info {
        padding: 10px 16px;
        flex-wrap: wrap;
        gap: 8px;
    }
    
    .user-welcome {
        font-size: 0.9rem;
    }
    
    .user-role {
        font-size: 0.75rem;
        padding: 4px 12px;
    }
    
    .logout-btn,
    .admin-btn {
        padding: 8px 14px;
        font-size: 0.85rem;
        min-height: 36px;
    }
    
    .answer-content {
        padding: 14px 16px;
    }
    
    .note-card {
        padding: 16px;
    }
    
    .initial-exam-paper {
        padding: 20px;
    }
    
    .exam-info-section {
        padding: 16px;
    }
    
    .exam-question-item {
        padding: 16px;
    }
    
    .answer-section {
        padding: 14px;
    }
    
    .score-section {
        flex-wrap: wrap;
    }
    
    .score-input {
        width: 80px;
    }
}

@media (hover: none) and (pointer: coarse) {
    .category-item:hover,
    .page-tab:hover,
    .question-card:hover,
    .note-card:hover,
    .exam-question-card:hover {
        transform: none;
    }
    
    .category-item:active,
    .page-tab:active,
    .question-answer-toggle:active,
    .exam-answer-toggle:active,
    .generate-exam-btn:active,
    .print-exam-btn:active,
    .save-exam-btn:active,
    .add-question-btn:active,
    .remove-question-btn:active,
    .login-btn:active,
    .logout-btn:active,
    .admin-btn:active {
        transform: scale(0.98);
        opacity: 0.9;
    }
}

@media (max-width: 360px) {
    .page-nav .container {
        padding: 6px 4px;
    }
    
    .page-tab {
        padding: 8px 8px;
        margin: 0 2px;
    }
    
    .tab-icon {
        font-size: 1.2rem;
    }
    
    .title {
        font-size: 1.15rem;
    }
    
    .subtitle {
        font-size: 0.75rem;
    }
    
    .question-card,
    .note-card,
    .exam-question-card {
        padding: 12px;
    }
    
    .question-text,
    .exam-question-text {
        font-size: 0.95rem;
    }
    
    .initial-exam-paper {
        padding: 16px;
    }
}

/* 超小屏幕设备 (iPhone SE, 小型安卓机) */
@media (max-width: 320px) {
    .container {
        padding: 0 8px;
    }
    
    .title {
        font-size: 1.1rem;
    }
    
    .subtitle {
        font-size: 0.7rem;
    }
    
    .page-tab {
        padding: 6px 6px;
        min-height: 36px;
    }
    
    .tab-icon {
        font-size: 1.1rem;
    }
    
    .question-card,
    .note-card,
    .exam-question-card {
        padding: 10px;
        border-radius: 8px;
    }
    
    .question-text,
    .exam-question-text {
        font-size: 0.9rem;
    }
    
    .category-item {
        padding: 10px 12px;
        min-height: 44px;
    }
    
    .category-icon {
        width: 32px;
        height: 32px;
        font-size: 1rem;
    }
    
    .sidebar {
        max-height: 200px;
    }
}

/* 大型手机 (iPhone Plus, Pro Max系列) */
@media (min-width: 414px) and (max-width: 480px) {
    .title {
        font-size: 1.35rem;
    }
    
    .question-text,
    .exam-question-text {
        font-size: 1.05rem;
    }
}

/* 平板设备横屏 */
@media (min-width: 1025px) and (max-width: 1366px) {
    .main .container {
        grid-template-columns: 260px 1fr;
        gap: 24px;
    }
    
    .sidebar {
        width: 260px;
    }
    
    .title {
        font-size: 2.4rem;
    }
}

/* 小型笔记本 */
@media (min-width: 1367px) and (max-width: 1600px) {
    .main .container {
        grid-template-columns: 300px 1fr;
        gap: 32px;
    }
    
    .container {
        max-width: 1300px;
    }
}

/* 大屏幕显示器 */
@media (min-width: 1920px) {
    .container {
        max-width: 1600px;
    }
    
    .main .container {
        grid-template-columns: 320px 1fr;
        gap: 40px;
    }
    
    .title {
        font-size: 3.2rem;
    }
    
    .question-text {
        font-size: 1.3rem;
    }
}

/* 超宽屏幕 */
@media (min-width: 2560px) {
    .container {
        max-width: 1800px;
    }
    
    .main .container {
        grid-template-columns: 350px 1fr;
        gap: 48px;
    }
}

/* 横屏手机 */
@media (max-height: 500px) and (orientation: landscape) {
    .header {
        padding: 16px 0;
    }
    
    .title {
        font-size: 1.3rem;
    }
    
    .sidebar {
        max-height: 150px;
    }
    
    .page-nav .container {
        padding: 4px 8px;
    }
    
    .page-tab {
        padding: 8px 12px;
        min-height: 40px;
    }
}

/* 高分辨率屏幕适配 */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
    .category-icon,
    .note-number,
    .question-number {
        -webkit-font-smoothing: antialiased;
        -moz-osx-font-smoothing: grayscale;
    }
}

/* 暗黑模式支持 */
@media (prefers-color-scheme: dark) {
    :root {
        color-scheme: dark;
    }
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* 打印样式 */
@media print {
    .header,
    .page-nav,
    .sidebar,
    .footer,
    .login-overlay,
    .user-info,
    .admin-btn,
    .logout-btn {
        display: none !important;
    }
    
    .main .container {
        grid-template-columns: 1fr;
    }
    
    .content {
        order: 0;
    }
    
    body {
        background: white;
        color: black;
    }
    
    .question-card,
    .exam-question-card {
        break-inside: avoid;
        page-break-inside: avoid;
        box-shadow: none;
        border: 1px solid #ccc;
    }
}