/* Modern CSS Reset and Variables */
:root {
    /* Modern Light Theme Color Palette */
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #8b5cf6;
    --secondary-color: #64748b;
    --secondary-dark: #475569;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;

    /* Light Theme Neutral Colors */
    --white: #ffffff;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;

    /* Background Colors */
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f1f5f9;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-muted: #64748b;

    /* Gradients - Simplified for light theme */
    --gradient-primary: linear-gradient(135deg, #6366f1 0%, #6366f1 100%);
    --gradient-secondary: linear-gradient(135deg, #64748b 0%, #475569 100%);
    --gradient-success: linear-gradient(135deg, #10b981 0%, #059669 100%);
    --gradient-card: var(--bg-secondary);

    /* Shadows - Enhanced for light theme */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    --shadow-card: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;

    /* Spacing - Enhanced for mobile */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;
    --spacing-24: 6rem;

    /* Mobile-specific spacing */
    --mobile-padding: 1.5rem;
    --mobile-gap: 1rem;
    --mobile-card-padding: 1.5rem;

    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: var(--font-size-base);
    min-height: 100vh;
    position: relative;
}

/* Remove dark theme gradient background */
body::before {
    display: none;
}

/* Modern Button Styles */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-3) var(--spacing-6);
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    font-size: var(--font-size-sm);
    font-weight: 500;
    text-decoration: none;
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
    white-space: nowrap;
    user-select: none;
    backdrop-filter: blur(10px);
    gap: var(--spacing-2);
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left var(--transition-normal);
}

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

.btn-primary {
    background: var(--gradient-primary);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary {
    background: var(--gradient-secondary);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

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

.btn-danger {
    background: linear-gradient(135deg, var(--error-color) 0%, #dc2626 100%);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

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

.btn-success {
    background: var(--gradient-success);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

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

/* Modern Message Styles */
.error-message {
    color: var(--error-color);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-3);
    padding: var(--spacing-4);
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.2);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(10px);
    position: relative;
    overflow: hidden;
}

.error-message::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 4px;
    height: 100%;
    background: var(--error-color);
}

.success-message {
    color: var(--success-color);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-3);
    padding: var(--spacing-4);
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.2);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(10px);
    position: relative;
    overflow: hidden;
}

.success-message::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 4px;
    height: 100%;
    background: var(--success-color);
}

/* Modern Login Screen */
.login-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: var(--spacing-5);
    position: relative;
}

.login-card {
    background: var(--bg-secondary);
    padding: var(--spacing-12);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-xl);
    width: 100%;
    max-width: 440px;
    position: relative;
    overflow: hidden;
    border: 1px solid var(--gray-200);
}

.login-card::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: conic-gradient(from 0deg, transparent, var(--primary-color), transparent);
    animation: rotate 10s linear infinite;
    z-index: -1;
}

.login-card::after {
    content: '';
    position: absolute;
    top: 2px;
    left: 2px;
    right: 2px;
    bottom: 2px;
    background: var(--bg-secondary);
    border-radius: var(--radius-2xl);
    z-index: -1;
}

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

    100% {
        transform: rotate(360deg);
    }
}

.login-card h1 {
    text-align: center;
    margin-bottom: var(--spacing-8);
    color: var(--text-primary);
    font-size: var(--font-size-3xl);
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Modern Form Styles */
.form-group {
    margin-bottom: var(--spacing-6);
    position: relative;
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-2);
    font-weight: 500;
    color: var(--text-primary);
    font-size: var(--font-size-sm);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: var(--spacing-4);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-base);
    background: var(--bg-secondary);
    color: var(--text-primary);
    transition: all var(--transition-fast);
    position: relative;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
    transform: translateY(-1px);
}

.form-group input:hover,
.form-group select:hover,
.form-group textarea:hover {
    border-color: var(--gray-300);
    transform: translateY(-1px);
}

.form-group small {
    color: var(--text-muted);
    font-size: var(--font-size-xs);
    margin-top: var(--spacing-2);
    display: block;
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

/* Modern Dashboard Header - Light Theme */
.dashboard-header {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--gray-200);
    padding: var(--spacing-6);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.dashboard-header h1 {
    color: var(--text-primary);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.user-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
}

.user-info span {
    font-weight: 500;
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
}

/* Modern Dashboard Tabs - Improved Readability */
.dashboard-tabs {
    display: flex;
    gap: var(--spacing-1);
    margin-bottom: var(--spacing-8);
    padding: var(--spacing-1);
    background: var(--bg-tertiary);
    border-radius: var(--radius-xl);
    border-radius: var(--radius-2xl);
    border: 1px solid rgba(148, 163, 184, 0.2);
    box-shadow: var(--shadow-lg);
    overflow-x: auto;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

.dashboard-tabs::-webkit-scrollbar {
    display: none;
}

.tab-btn {
    padding: var(--spacing-4) var(--spacing-6);
    border: none;
    background: transparent;
    cursor: pointer;
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: var(--radius-xl);
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
    white-space: nowrap;
    min-width: fit-content;
    text-align: center;
    user-select: none;
}

.tab-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--gradient-primary);
    opacity: 0;
    transition: all var(--transition-fast);
    z-index: -1;
    border-radius: var(--radius-xl);
}

.tab-btn.active {
    color: var(--white);
    font-weight: 600;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.tab-btn.active::before {
    opacity: 1;
}

.tab-btn:hover {
    color: var(--text-primary);
    transform: translateY(-1px);
}

.tab-btn:hover:not(.active) {
    background: var(--gray-100);
    color: var(--text-primary);
}

.tab-content {
    display: none;
    animation: fadeIn var(--transition-normal);
}

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

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

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.tab-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-8);
}

.tab-header h2 {
    margin: 0;
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--gray-800);
}

/* Modern Dashboard Content */
.dashboard-content {
    padding: var(--spacing-8);
    max-width: 1400px;
    margin: 0 auto;
}

/* Mobile-friendly Tab Improvements */
@media (max-width: 640px) {
    .dashboard-tabs {
        padding: var(--spacing-1);
        gap: var(--spacing-1);
        margin-bottom: var(--spacing-6);
    }

    .tab-btn {
        padding: var(--spacing-3) var(--spacing-4);
        font-size: var(--font-size-xs);
        min-width: auto;
        flex: 1;
    }
}

/* Modern Selector Styles */
.course-selector,
.assignment-selector,
.assignment-filter,
.report-selector {
    margin-bottom: var(--spacing-6);
    padding: var(--spacing-6);
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--gray-200);
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
    flex-wrap: wrap;
}

.course-selector label,
.assignment-selector label,
.assignment-filter label,
.report-selector label {
    font-weight: 500;
    color: var(--text-primary);
    font-size: var(--font-size-sm);
}

.course-selector select,
.assignment-selector select,
.assignment-filter select,
.report-selector select {
    min-width: 200px;
    padding: var(--spacing-3);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: var(--font-size-sm);
    transition: all var(--transition-fast);
}

.course-selector select:focus,
.assignment-selector select:focus,
.assignment-filter select:focus,
.report-selector select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Modern Assignments Grid */
.assignments-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-6);
    margin-top: var(--spacing-6);
}

.assignment-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-card);
    border: 1px solid var(--gray-200);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.assignment-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient-primary);
}

.assignment-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    border-color: var(--gray-300);
}

.assignment-card h3 {
    margin-bottom: var(--spacing-4);
    color: var(--text-primary);
    font-size: var(--font-size-xl);
    font-weight: 600;
    line-height: 1.2;
}

.assignment-card p {
    margin-bottom: var(--spacing-3);
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    line-height: 1.5;
}

.assignment-card .due-date {
    font-weight: 600;
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--radius-full);
    font-size: var(--font-size-xs);
    display: inline-block;
    margin-bottom: var(--spacing-4);
}

.assignment-card .due-date.past {
    background: rgba(100, 116, 139, 0.1);
    color: var(--text-secondary);
}

.assignment-card .due-date.soon {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning-color);
}

.assignment-card .due-date:not(.past):not(.soon) {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
}

.assignment-card .assignment-actions {
    margin-top: var(--spacing-6);
    display: flex;
    gap: var(--spacing-3);
    flex-wrap: wrap;
}

/* Modern Submissions Grid */
.submissions-grid {
    display: grid;
    gap: var(--spacing-6);
    margin-top: var(--spacing-6);
}

.submission-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-card);
    border: 1px solid var(--gray-200);
    transition: all var(--transition-normal);
}

.submission-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    border-color: var(--gray-300);
}

.submission-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-6);
    padding-bottom: var(--spacing-4);
    border-bottom: 1px solid var(--gray-200);
}

.submission-header h4 {
    margin: 0;
    color: var(--gray-800);
    font-size: var(--font-size-lg);
    font-weight: 600;
}

.submission-date {
    color: var(--gray-500);
    font-size: var(--font-size-sm);
    font-weight: 500;
}

.submission-meta {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-3);
    margin-bottom: var(--spacing-6);
}

.submission-meta span {
    padding: var(--spacing-2) var(--spacing-4);
    background: rgba(99, 102, 241, 0.1);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-xs);
    font-weight: 500;
    color: var(--primary-color);
    text-align: center;
}

.submission-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-6);
}

.summary-item {
    text-align: center;
    padding: var(--spacing-4);
    border-radius: var(--radius-lg);
    background: rgba(248, 250, 252, 0.8);
    backdrop-filter: blur(10px);
    transition: all var(--transition-fast);
}

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

.summary-item .number {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    display: block;
    margin-bottom: var(--spacing-1);
}

.summary-item .label {
    font-size: var(--font-size-xs);
    color: var(--gray-600);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 500;
}

.summary-item.passed {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
}

.summary-item.failed {
    background: rgba(239, 68, 68, 0.1);
    color: var(--error-color);
}

.summary-item.total {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
}

.success-rate {
    text-align: center;
    font-size: var(--font-size-lg);
    font-weight: 700;
    padding: var(--spacing-6);
    border-radius: var(--radius-xl);
    margin-bottom: var(--spacing-6);
    position: relative;
    overflow: hidden;
}

.success-rate::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0.1;
    background: linear-gradient(45deg, transparent 30%, rgba(255, 255, 255, 0.5) 50%, transparent 70%);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% {
        transform: translateX(-100%);
    }

    100% {
        transform: translateX(100%);
    }
}

.success-rate.high {
    background: var(--gradient-success);
    color: var(--white);
}

.success-rate.medium {
    background: linear-gradient(135deg, var(--warning-color) 0%, #f97316 100%);
    color: var(--white);
}

.success-rate.low {
    background: linear-gradient(135deg, var(--error-color) 0%, #dc2626 100%);
    color: var(--white);
}

/* Modern Profile Card */
.profile-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-card);
    border: 1px solid var(--gray-200);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-8);
    transition: all var(--transition-normal);
}

.profile-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    border-color: var(--gray-300);
}

.profile-info h3,
.password-change h3 {
    margin-bottom: var(--spacing-6);
    color: var(--text-primary);
    font-size: var(--font-size-xl);
    font-weight: 600;
    position: relative;
}

.profile-info h3::after,
.password-change h3::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 40px;
    height: 3px;
    background: var(--gradient-primary);
    border-radius: var(--radius-full);
}

.profile-info p {
    margin-bottom: var(--spacing-4);
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    line-height: 1.6;
}

.profile-info p strong {
    color: var(--text-primary);
    font-weight: 600;
}

.form-buttons {
    display: flex;
    gap: var(--spacing-3);
    justify-content: flex-end;
    margin-top: var(--spacing-6);
}

/* Modern Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(10px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: var(--bg-secondary);
    padding: var(--spacing-10);
    border-radius: var(--radius-2xl);
    width: 90%;
    max-width: 500px;
    position: relative;
    box-shadow: var(--shadow-xl);
    border: 1px solid var(--gray-200);
    transform: scale(0.9) translateY(20px);
    transition: all var(--transition-normal);
}

.modal.active .modal-content {
    transform: scale(1) translateY(0);
}

.modal-content h2 {
    margin-bottom: var(--spacing-6);
    color: var(--text-primary);
    font-size: var(--font-size-2xl);
    font-weight: 600;
}

.close {
    position: absolute;
    top: var(--spacing-4);
    right: var(--spacing-4);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    cursor: pointer;
    color: var(--gray-400);
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
}

.close:hover {
    color: var(--gray-600);
    background: rgba(255, 255, 255, 0.2);
    transform: scale(1.1);
}

/* Modern Loading Spinner */
.loading {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.loading.active {
    opacity: 1;
    visibility: visible;
}

.spinner {
    width: 60px;
    height: 60px;
    border: 4px solid var(--gray-200);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: var(--spacing-4);
}

.loading p {
    color: var(--gray-600);
    font-size: var(--font-size-sm);
    font-weight: 500;
}

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

    100% {
        transform: rotate(360deg);
    }
}

/* Modern Report Container */
.report-container {
    background: var(--gradient-card);
    backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-lg);
    border: 1px solid rgba(255, 255, 255, 0.2);
    margin-top: var(--spacing-6);
    overflow: hidden;
}

.report-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: var(--spacing-6);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.report-table th,
.report-table td {
    padding: var(--spacing-4);
    text-align: left;
    border-bottom: 1px solid var(--gray-200);
    font-size: var(--font-size-sm);
}

.report-table th {
    background: var(--gradient-primary);
    color: var(--white);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-size: var(--font-size-xs);
}

.report-table tr:hover {
    background: rgba(99, 102, 241, 0.05);
}

.report-table tr:last-child td {
    border-bottom: none;
}

/* Status Badges */
.status-badge {
    padding: var(--spacing-2) var(--spacing-3);
    border-radius: var(--radius-full);
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: inline-block;
}

.status-badge.submitted {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
}

.status-badge.not-submitted {
    background: rgba(239, 68, 68, 0.1);
    color: var(--error-color);
}

.status-badge.past-due {
    background: rgba(100, 116, 139, 0.1);
    color: var(--secondary-color);
}

/* Screen Management */
.screen {
    display: none;
    min-height: 100vh;
}

.screen.active {
    display: block;
}

/* Modern Responsive Design - Enhanced Mobile Spacing */
@media (max-width: 768px) {
    .dashboard-header {
        flex-direction: column;
        gap: var(--spacing-4);
        align-items: flex-start;
        padding: var(--mobile-padding);
    }

    .dashboard-header h1 {
        font-size: var(--font-size-xl);
    }

    .user-info {
        width: 100%;
        justify-content: space-between;
    }

    .dashboard-content {
        padding: var(--mobile-padding);
    }

    .dashboard-tabs {
        flex-wrap: wrap;
        gap: var(--spacing-2);
        padding: var(--spacing-3);
        margin-bottom: var(--spacing-6);
    }

    .tab-btn {
        padding: var(--spacing-3) var(--spacing-5);
        font-size: var(--font-size-sm);
        min-height: 44px;
        /* Better touch target */
    }

    .assignments-grid {
        grid-template-columns: 1fr;
        gap: var(--mobile-gap);
    }

    .assignment-card {
        padding: var(--mobile-card-padding);
        margin-bottom: var(--spacing-4);
    }

    .profile-card {
        grid-template-columns: 1fr;
        gap: var(--spacing-6);
        padding: var(--mobile-card-padding);
    }

    .submission-meta {
        grid-template-columns: 1fr;
        gap: var(--spacing-4);
    }

    .submission-summary {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-4);
    }

    .modal-content {
        width: 95%;
        padding: var(--mobile-card-padding);
        margin: var(--spacing-4);
    }

    .course-selector,
    .assignment-selector,
    .assignment-filter,
    .report-selector {
        flex-direction: column;
        gap: var(--spacing-4);
        align-items: stretch;
    }

    .course-selector select,
    .assignment-selector select,
    .assignment-filter select,
    .report-selector select {
        width: 100%;
        min-width: auto;
        padding: var(--spacing-3);
        font-size: var(--font-size-base);
    }

    .login-card {
        padding: var(--spacing-8);
        margin: var(--spacing-4);
    }

    .assignment-card .assignment-actions {
        flex-direction: column;
        gap: var(--spacing-3);
    }

    .assignment-card .assignment-actions .btn {
        width: 100%;
        justify-content: center;
        min-height: 44px;
    }

    .form-buttons {
        flex-direction: column;
        gap: var(--spacing-3);
    }

    .form-buttons .btn {
        width: 100%;
        min-height: 44px;
    }
}

@media (max-width: 480px) {
    .dashboard-content {
        padding: var(--spacing-4);
    }

    .dashboard-header {
        padding: var(--spacing-4);
    }

    .tab-btn {
        padding: var(--spacing-3) var(--spacing-4);
        font-size: var(--font-size-sm);
        min-height: 44px;
    }

    .assignment-card,
    .submission-card {
        padding: var(--spacing-6);
        margin-bottom: var(--spacing-4);
    }

    .assignment-card h3 {
        font-size: var(--font-size-lg);
        margin-bottom: var(--spacing-3);
    }

    .assignment-card p {
        margin-bottom: var(--spacing-4);
        line-height: 1.6;
    }

    .assignment-card .due-date {
        padding: var(--spacing-3) var(--spacing-4);
        margin-bottom: var(--spacing-5);
    }

    .submission-summary {
        grid-template-columns: 1fr;
        gap: var(--spacing-3);
    }

    .login-card {
        padding: var(--spacing-6);
        margin: var(--spacing-3);
    }

    .login-card h1 {
        font-size: var(--font-size-2xl);
    }

    .modal-content {
        padding: var(--spacing-5);
        margin: var(--spacing-3);
    }

    .report-table {
        font-size: var(--font-size-sm);
    }

    .report-table th,
    .report-table td {
        padding: var(--spacing-3);
    }

    .form-group {
        margin-bottom: var(--spacing-5);
    }

    .form-group label {
        margin-bottom: var(--spacing-2);
        font-size: var(--font-size-sm);
    }

    .form-group input,
    .form-group select,
    .form-group textarea {
        padding: var(--spacing-3);
        font-size: var(--font-size-base);
    }
}

/* Accessibility Improvements */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Print Styles */
@media print {

    .btn,
    .dashboard-header,
    .dashboard-tabs,
    .assignment-actions,
    .modal {
        display: none !important;
    }

    .assignment-card,
    .submission-card {
        box-shadow: none;
        border: 1px solid var(--gray-300);
    }
}

#instructor-student-id-filter {
    max-width: 200px;
    padding: 0.3em 0.7em;
    border: 1px solid #bbb;
    border-radius: 5px;
    font-size: 1em;
    background: #fafbfc;
    transition: border-color 0.2s;
    margin-left: 0.2em;
}

#instructor-student-id-filter:focus {
    border-color: #0078d4;
    outline: none;
    background: #fff;
}