:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --secondary-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --dark: #1f2937;
    --dark-light: #374151;
    --light: #f3f4f6;
    --border: #e5e7eb;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --white: #ffffff;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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);
    --radius: 8px;
    --radius-lg: 12px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Login Page */
.login-container {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 20px;
}

.login-card {
    background: var(--white);
    padding: 40px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 450px;
    animation: slideUp 0.5s ease;
}

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

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

.login-header {
    text-align: center;
    margin-bottom: 30px;
}

.login-header h1 {
    color: var(--primary-color);
    font-size: 28px;
    margin-bottom: 10px;
}

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

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 14px;
}

.form-control {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid var(--border);
    border-radius: var(--radius);
    font-size: 14px;
    transition: var(--transition);
    background: var(--white);
}

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

.btn {
    display: inline-block;
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    text-align: center;
}

.btn-primary {
    background: var(--primary-color);
    color: var(--white);
    width: 100%;
}

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

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

.btn-secondary:hover {
    background: #059669;
    transform: translateY(-2px);
}

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

.btn-danger:hover {
    background: #dc2626;
}

.btn-sm {
    padding: 8px 16px;
    font-size: 13px;
}

.alert {
    padding: 12px 15px;
    border-radius: var(--radius);
    margin-bottom: 20px;
    font-size: 14px;
}

.alert-danger {
    background: #fee2e2;
    color: #991b1b;
    border-left: 4px solid var(--danger-color);
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border-left: 4px solid var(--secondary-color);
}

.alert-warning {
    background: #fed7aa;
    color: #92400e;
    border-left: 4px solid var(--warning-color);
}

/* Dashboard Layout */
.dashboard {
    display: flex;
    min-height: 100vh;
    background: var(--light);
}

.sidebar {
    width: 260px;
    background: var(--dark);
    color: var(--white);
    padding: 20px 0;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
}

.sidebar-header {
    padding: 0 20px 20px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    margin-bottom: 20px;
}

.sidebar-header h2 {
    font-size: 18px;
    color: var(--white);
}

.nav-menu {
    list-style: none;
}

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

.nav-link {
    display: flex;
    align-items: center;
    padding: 12px 20px;
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
}

.nav-link:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
}

.nav-link.active {
    background: var(--primary-color);
    color: var(--white);
}

.nav-link i {
    margin-right: 10px;
    width: 20px;
    text-align: center;
}

.main-content {
    flex: 1;
    margin-left: 260px;
    padding: 20px;
}

.top-bar {
    background: var(--white);
    padding: 15px 25px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    margin-bottom: 25px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.page-title {
    font-size: 24px;
    color: var(--text-primary);
    font-weight: 700;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 15px;
}

.user-avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--primary-color);
    color: var(--white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
}

/* Cards */
.card {
    background: var(--white);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    padding: 25px;
    margin-bottom: 20px;
}

.card-header {
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--light);
}

.card-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 20px;
    margin-bottom: 25px;
}

.stat-card {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: var(--white);
    padding: 25px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.stat-card.green {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
}

.stat-card.orange {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
}

.stat-card.purple {
    background: linear-gradient(135deg, #8b5cf6 0%, #7c3aed 100%);
}

.stat-icon {
    font-size: 32px;
    margin-bottom: 10px;
    opacity: 0.9;
}

.stat-label {
    font-size: 14px;
    opacity: 0.9;
    margin-bottom: 5px;
}

.stat-value {
    font-size: 32px;
    font-weight: 700;
}

/* Table */
.table-responsive {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    margin-bottom: 20px;
    border-radius: var(--radius);
}

/* Add scrollbar styling for better visibility */
.table-responsive::-webkit-scrollbar {
    height: 8px;
}

.table-responsive::-webkit-scrollbar-track {
    background: var(--light);
    border-radius: 4px;
}

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

.table-responsive::-webkit-scrollbar-thumb:hover {
    background: var(--primary-dark);
}

table {
    width: 100%;
    border-collapse: collapse;
    min-width: 600px;
    /* Minimum width to prevent squeezing */
}

thead {
    background: var(--light);
}

th {
    padding: 12px;
    text-align: left;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 14px;
    border-bottom: 2px solid var(--border);
    white-space: nowrap;
    /* Prevent text wrapping in headers */
}

td {
    padding: 12px;
    border-bottom: 1px solid var(--border);
    font-size: 14px;
}

tbody tr:hover {
    background: var(--light);
}

/* Badge */
.badge {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 600;
}

.badge-success {
    background: #d1fae5;
    color: #065f46;
}

.badge-warning {
    background: #fed7aa;
    color: #92400e;
}

.badge-danger {
    background: #fee2e2;
    color: #991b1b;
}

.badge-primary {
    background: #dbeafe;
    color: #1e40af;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--white);
    border-radius: var(--radius-lg);
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideUp 0.3s ease;
}

.modal-header {
    padding: 20px 25px;
    border-bottom: 2px solid var(--light);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-title {
    font-size: 20px;
    font-weight: 700;
}

.modal-close {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-secondary);
}

.modal-body {
    padding: 25px;
}

.modal-footer {
    padding: 20px 25px;
    border-top: 2px solid var(--light);
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

/* Form columns */
.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

/* File upload */
.file-upload-area {
    border: 2px dashed var(--border);
    border-radius: var(--radius-lg);
    padding: 40px;
    text-align: center;
    background: var(--light);
    cursor: pointer;
    transition: var(--transition);
}

.file-upload-area:hover {
    border-color: var(--primary-color);
    background: #eff6ff;
}

.file-upload-area.drag-over {
    border-color: var(--primary-color);
    background: #dbeafe;
}

.upload-icon {
    font-size: 48px;
    color: var(--primary-color);
    margin-bottom: 15px;
}

/* Actions */
.actions {
    display: flex;
    gap: 8px;
}

.btn-icon {
    width: 32px;
    height: 32px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius);
    border: none;
    cursor: pointer;
    transition: var(--transition);
}

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

/* Menu Toggle Button */
.menu-toggle {
    display: none;
    position: fixed;
    top: 15px;
    left: 15px;
    z-index: 1100;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    width: 45px;
    height: 45px;
    border-radius: var(--radius);
    cursor: pointer;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    align-items: center;
    justify-content: center;
    font-size: 20px;
}

.menu-toggle:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}

.menu-toggle:active {
    transform: scale(0.95);
}

/* Overlay for mobile menu */
.sidebar-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 999;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.sidebar-overlay.active {
    opacity: 1;
}

/* Responsive Breakpoints */

/* Large tablets and small desktops (768px - 1024px) */
@media (max-width: 1024px) {
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .modal-content {
        width: 95%;
    }
}

/* Tablets (768px - 1023px) */
@media (max-width: 1023px) {
    .sidebar {
        width: 240px;
    }

    .main-content {
        margin-left: 240px;
    }

    .page-title {
        font-size: 20px;
    }

    .card {
        padding: 20px;
    }
}

/* Mobile and small tablets (max-width: 768px) */
@media (max-width: 768px) {
    .menu-toggle {
        display: flex;
    }

    .sidebar {
        width: 280px;
        position: fixed;
        left: -280px;
        top: 0;
        height: 100vh;
        z-index: 1000;
        transition: left 0.3s ease;
    }

    .sidebar.active {
        left: 0;
    }

    .sidebar-overlay.active {
        display: block;
    }

    .main-content {
        margin-left: 0;
        padding: 80px 15px 15px;
    }

    .top-bar {
        flex-direction: column;
        gap: 15px;
        padding: 15px;
        align-items: flex-start;
    }

    .page-title {
        font-size: 20px;
    }

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

    .stats-grid {
        grid-template-columns: 1fr;
        gap: 15px;
    }

    .stat-card {
        padding: 20px;
    }

    .stat-value {
        font-size: 28px;
    }

    .card {
        padding: 15px;
    }

    .card-header {
        margin-bottom: 15px;
        padding-bottom: 12px;
    }

    .table-responsive {
        font-size: 12px;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }

    table {
        min-width: 600px;
    }

    th,
    td {
        padding: 8px 6px;
        font-size: 12px;
    }

    .actions {
        flex-wrap: nowrap;
    }

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

    .form-row {
        grid-template-columns: 1fr;
    }

    .modal-content {
        width: 95%;
        max-height: 85vh;
    }

    .modal-header,
    .modal-body,
    .modal-footer {
        padding: 15px;
    }

    .login-card {
        padding: 30px 20px;
    }

    .course-grid,
    .material-grid {
        grid-template-columns: 1fr;
    }
}

/* Small mobile devices (max-width: 480px) */
@media (max-width: 480px) {
    .main-content {
        padding: 70px 10px 10px;
    }

    .menu-toggle {
        width: 40px;
        height: 40px;
        font-size: 18px;
    }

    .top-bar {
        padding: 12px;
    }

    .page-title {
        font-size: 18px;
    }

    .user-info {
        font-size: 12px;
    }

    .user-avatar {
        width: 35px;
        height: 35px;
        font-size: 14px;
    }

    .stat-card {
        padding: 15px;
    }

    .stat-icon {
        font-size: 28px;
    }

    .stat-label {
        font-size: 13px;
    }

    .stat-value {
        font-size: 24px;
    }

    .card {
        padding: 12px;
        margin-bottom: 15px;
    }

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

    .btn {
        padding: 10px 20px;
        font-size: 13px;
    }

    .btn-sm {
        padding: 6px 10px;
        font-size: 11px;
    }

    .form-group {
        margin-bottom: 15px;
    }

    .form-control {
        padding: 10px 12px;
        font-size: 14px;
    }

    .modal-title {
        font-size: 18px;
    }

    .modal-footer {
        flex-direction: column;
        gap: 8px;
    }

    .modal-footer .btn {
        width: 100%;
    }

    .alert {
        padding: 10px 12px;
        font-size: 13px;
    }

    .login-card {
        padding: 25px 15px;
    }

    .login-header h1 {
        font-size: 24px;
    }

    .file-upload-area {
        padding: 30px 15px;
    }

    .upload-icon {
        font-size: 36px;
    }

    table {
        min-width: 500px;
    }

    th,
    td {
        padding: 6px 4px;
        font-size: 11px;
    }

    .badge {
        padding: 3px 8px;
        font-size: 10px;
    }
}

/* Very small devices (max-width: 360px) */
@media (max-width: 360px) {
    .sidebar {
        width: 260px;
        left: -260px;
    }

    .main-content {
        padding: 65px 8px 8px;
    }

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

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

    .btn-icon {
        width: 28px;
        height: 28px;
        font-size: 12px;
    }
}

/* Loading spinner */
.spinner {
    border: 3px solid var(--light);
    border-top: 3px solid var(--primary-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 20px auto;
}

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

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

/* Material cards */
.material-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 20px;
}

.material-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    padding: 20px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 2px solid transparent;
}

.material-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.material-icon-large {
    font-size: 48px;
    text-align: center;
    margin-bottom: 15px;
}

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

.material-meta {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 15px;
}

/* Course cards */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.course-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.course-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: var(--white);
    padding: 20px;
}

.course-body {
    padding: 20px;
}

.course-title {
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 8px;
}

.course-level {
    display: inline-block;
    padding: 4px 12px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 12px;
    font-size: 12px;
}

.course-info {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 15px;
}

.info-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    color: var(--text-secondary);
}

/* Search bar */
.search-bar {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.search-input {
    flex: 1;
    padding: 10px 15px;
    border: 2px solid var(--border);
    border-radius: var(--radius);
    font-size: 14px;
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

select.form-control {
    background: var(--white);
    cursor: pointer;
}

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

.empty-state-icon {
    font-size: 64px;
    margin-bottom: 20px;
    opacity: 0.5;
}

.empty-state-text {
    font-size: 18px;
    margin-bottom: 10px;
}

/* Error field highlighting */
.error-field {
    border-color: var(--danger-color) !important;
    box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.1) !important;
    animation: shake 0.3s ease;
}

@keyframes shake {

    0%,
    100% {
        transform: translateX(0);
    }

    25% {
        transform: translateX(-5px);
    }

    75% {
        transform: translateX(5px);
    }
}


/* Dashboard specific grid - 2 columns that becomes 1 on mobile */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

@media (max-width: 768px) {
    .dashboard-grid {
        grid-template-columns: 1fr;
    }
}

/* Action buttons grid - responsive auto-fit */
.action-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

@media (max-width: 480px) {
    .action-buttons {
        grid-template-columns: 1fr;
    }
}