:root {
    /* Updated color palette */
    --dark-bg: #121418;
    --card-bg: #1e2228;
    --card-hover: #262a32;
    --primary-color: #dc3545;
    --accent-color: #e4606d;
    --light-red: #ff6b6b;
    --dark-red: #c72333;
    --text-primary: rgba(255, 255, 255, 0.95);
    --text-secondary: rgba(255, 255, 255, 0.75);
    --text-muted: rgba(255, 255, 255, 0.5);
    --border-color: rgba(255, 255, 255, 0.12);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.15);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.25);
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

body.dark-theme {
    background-color: var(--dark-bg);
    color: var(--text-primary);
    font-family: 'Poppins', sans-serif;
    line-height: 1.6;
    letter-spacing: 0.3px;
}

h1, h2, h3, h4, h5, h6 {
    color: var(--text-primary);
    font-weight: 600;
    letter-spacing: -0.02em;
}

p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

/* Navbar Styles */
.navbar {
    background-color: rgba(30, 34, 40, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    box-shadow: var(--shadow-sm);
}

.navbar-brand {
    font-weight: 600;
    font-size: 1.25rem;
    color: var(--text-primary) !important;
}

.navbar-brand i {
    color: var(--primary-color);
    margin-right: 0.5rem;
}

.nav-link {
    color: var(--text-secondary) !important;
    font-weight: 500;
    transition: color 0.3s ease;
    padding: 0.5rem 1rem !important;
}

.nav-link:hover {
    color: var(--text-primary) !important;
}

.nav-link i {
    margin-right: 0.5rem;
}

/* Lesson Cards and Play Button */
.lesson-card {
    background: var(--card-bg);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    border: 1px solid var(--border-color);
    height: 100%;
    position: relative;
}

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

.lesson-thumbnail {
    position: relative;
    padding-top: 56.25%; /* 16:9 Aspect Ratio */
    background-color: rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

.lesson-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

.lesson-card:hover .lesson-thumbnail img {
    transform: scale(1.05);
}

.lesson-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.lesson-card:hover .lesson-overlay {
    opacity: 1;
}

.btn-play {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-decoration: none;
    transform: scale(0.8);
    transition: all var(--transition-normal);
    border: 2px solid rgba(255, 255, 255, 0.2);
    box-shadow: 0 0 20px rgba(220, 53, 69, 0.4);
}

.btn-play i {
    font-size: 1.5rem;
    margin-left: 4px; /* Offset for play icon */
}

.lesson-card:hover .btn-play {
    transform: scale(1);
    background: var(--accent-color);
    border-color: rgba(255, 255, 255, 0.4);
    box-shadow: 0 0 30px rgba(220, 53, 69, 0.6);
}

.btn-play:hover {
    background: var(--light-red);
    color: white;
    transform: scale(1.1) !important;
}

.lesson-content {
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.lesson-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 0;
    line-height: 1.4;
}

.lesson-title a {
    color: var(--text-primary);
    text-decoration: none;
    transition: color var(--transition-normal);
}

.lesson-title a:hover {
    color: var(--primary-color);
}

.lesson-description {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin: 0;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.5;
}

.lesson-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-top: auto;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.lesson-meta .meta-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.lesson-meta i {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Button Styles */
.btn {
    font-weight: 500;
    letter-spacing: 0.3px;
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    transition: all var(--transition-normal);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--dark-red));
    border: none;
    box-shadow: 0 2px 4px rgba(220, 53, 69, 0.3);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--light-red), var(--primary-color));
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(220, 53, 69, 0.4);
}

/* Resource Cards */
.resource-card {
    background-color: var(--card-bg);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1rem;
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
}

.resource-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background-color: var(--primary-color);
    transform: scaleY(0);
    transition: transform 0.3s ease;
}

.resource-card:hover::before {
    transform: scaleY(1);
}

.resource-card:hover {
    transform: translateX(10px);
    background-color: var(--card-hover);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.resource-content h4 {
    color: var(--text-primary);
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.resource-content p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
    line-height: 1.5;
}

/* Delete button styling */
.btn-danger {
    background-color: var(--dark-red);
    border-color: var(--dark-red);
    transition: all 0.3s ease;
}

.btn-danger:hover {
    background-color: var(--light-red);
    border-color: var(--light-red);
    transform: translateY(-1px);
}

.delete-resource {
    opacity: 0;
    transition: all 0.3s ease;
}

.resource-card:hover .delete-resource {
    opacity: 1;
}

/* Form Styles */
.form-control {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    border-radius: 8px;
    padding: 0.75rem 1rem;
    transition: all var(--transition-normal);
}

.form-control:focus {
    background-color: var(--card-hover);
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(220, 53, 69, 0.15);
    color: var(--text-primary);
}

/* Alerts */
.alert {
    border-radius: 10px;
    padding: 1rem;
    margin-bottom: 1.5rem;
    animation: fadeIn 0.5s ease;
    border: none;
}

.alert-success {
    background-color: rgba(40, 167, 69, 0.2);
    border-left: 4px solid #28a745;
    color: #98ff98;
}

.alert-danger {
    background-color: rgba(220, 53, 69, 0.2);
    border-left: 4px solid #dc3545;
    color: #ff8b8b;
}

.alert-info {
    background-color: rgba(23, 162, 184, 0.2);
    border-left: 4px solid #17a2b8;
    color: #8be0ed;
}

/* Breadcrumb Styling */
.breadcrumb {
    background: rgba(255, 255, 255, 0.05);
    padding: 1rem 1.5rem;
    border-radius: 10px;
    margin-bottom: 2rem;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.breadcrumb-item {
    font-size: 0.95rem;
    font-weight: 500;
    letter-spacing: 0.3px;
}

.breadcrumb-item a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

.breadcrumb-item a:hover {
    color: var(--light-red);
}

.breadcrumb-item.active {
    color: rgba(255, 255, 255, 0.7);
}

.breadcrumb-item + .breadcrumb-item::before {
    content: "›";
    color: rgba(255, 255, 255, 0.4);
    font-size: 1.2rem;
    line-height: 1;
    padding: 0 0.8rem;
}

/* Confirmation dialog styling */
.swal2-popup {
    background: var(--dark-bg) !important;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.swal2-title, .swal2-content {
    color: rgba(255, 255, 255, 0.9) !important;
}

.swal2-actions button {
    border-radius: 6px !important;
    font-weight: 500 !important;
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.lesson-card {
    animation: fadeIn 0.5s ease forwards;
}

/* Loading states */
.loading-skeleton {
    background: linear-gradient(90deg, var(--card-bg) 25%, var(--card-hover) 50%, var(--card-bg) 75%);
    background-size: 200% 100%;
    animation: loading 1.5s infinite;
}

@keyframes loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* Responsive Design */
@media (max-width: 768px) {
    .navbar {
        padding: 0.5rem 0;
    }
    
    .card-content {
        padding: 1rem;
    }
    
    .video-container {
        margin: -1rem -1rem 1rem -1rem;
        border-radius: 0;
    }
    
    .video-container iframe {
        height: 300px;
    }
}

/* Form Styling */
.custom-input {
    background-color: rgba(255, 255, 255, 0.05) !important;
    border: 1px solid rgba(255, 255, 255, 0.1) !important;
    color: rgba(255, 255, 255, 0.9) !important;
    padding: 0.8rem 1rem;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.custom-input:focus {
    background-color: rgba(255, 255, 255, 0.1) !important;
    border-color: var(--primary-color) !important;
    box-shadow: 0 0 0 0.2rem rgba(220, 53, 69, 0.25) !important;
}

.custom-input::placeholder {
    color: rgba(255, 255, 255, 0.4);
}

.form-label {
    color: rgba(255, 255, 255, 0.9);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.form-select {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3e%3cpath fill='none' stroke='%23ffffff' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='m2 5 6 6 6-6'/%3e%3c/svg%3e") !important;
}

.bg-dark-card {
    background: rgba(30, 32, 35, 0.95) !important;
    border: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.card-header {
    padding: 1.5rem 1.5rem 1rem;
}

.card-body {
    padding: 1.5rem;
}

.card-title {
    color: rgba(255, 255, 255, 0.9);
    font-weight: 600;
}

.btn-outline-light {
    border-color: rgba(255, 255, 255, 0.2);
}

.btn-outline-light:hover {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.3);
}

.invalid-feedback {
    font-size: 0.85rem;
    color: var(--bs-danger);
}

/* Animation for form elements */
.form-group {
    opacity: 0;
    transform: translateY(10px);
    animation: fadeInUp 0.5s ease forwards;
}

.form-group:nth-child(1) { animation-delay: 0.1s; }
.form-group:nth-child(2) { animation-delay: 0.2s; }
.form-group:nth-child(3) { animation-delay: 0.3s; }
.form-group:nth-child(4) { animation-delay: 0.4s; }

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

/* Table styles */
.table {
    color: var(--text-secondary);
}

.table thead th {
    background-color: var(--card-bg);
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
    font-weight: 600;
}

.table td {
    border-color: var(--border-color);
    vertical-align: middle;
}

/* Enhanced Select Dropdown */
.form-select.custom-input {
    background-color: var(--card-bg);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.75rem 1rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    background-image: linear-gradient(45deg, transparent 50%, var(--text-secondary) 50%),
                      linear-gradient(135deg, var(--text-secondary) 50%, transparent 50%);
    background-position: calc(100% - 20px) calc(1em + 4px),
                         calc(100% - 15px) calc(1em + 4px);
    background-size: 5px 5px,
                    5px 5px;
    background-repeat: no-repeat;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
}

.form-select.custom-input:focus {
    background-color: var(--card-hover);
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(220, 53, 69, 0.15);
    outline: none;
}

.form-select.custom-input option {
    background-color: var(--card-bg);
    color: var(--text-primary);
    padding: 12px;
}

.form-select.custom-input:hover {
    background-color: var(--card-hover);
    border-color: var(--border-color);
}

.form-select.custom-input::-ms-expand {
    display: none;
}

/* Custom Select Container */
.select-container {
    position: relative;
    margin-bottom: 1.5rem;
}

.select-container::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 3px;
    height: 100%;
    background: linear-gradient(to bottom, var(--primary-color), var(--dark-red));
    opacity: 0;
    transition: opacity var(--transition-normal);
    border-top-right-radius: 8px;
    border-bottom-right-radius: 8px;
}

.select-container:hover::after {
    opacity: 1;
}

.form-label {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.form-label i {
    color: var(--primary-color);
    font-size: 1rem;
}

/* Course Cards */
.course-card {
    background: var(--card-bg);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    border: 1px solid var(--border-color);
    height: 100%;
}

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

.course-card .card-img-top {
    height: 200px;
    object-fit: cover;
    border-bottom: 1px solid var(--border-color);
}

.course-card .card-body {
    padding: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.course-card .card-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 0;
    color: var(--text-primary);
    line-height: 1.4;
}

.course-card .card-text {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin: 0;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.5;
}

.course-card .badge {
    font-size: 0.8rem;
    padding: 0.4rem 0.8rem;
    font-weight: 500;
}

.course-card .btn-group {
    gap: 0.5rem;
}

.course-card .btn {
    padding: 0.4rem 1rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.course-card .btn i {
    font-size: 0.9rem;
}

.course-card .course-thumbnail {
    position: relative;
    padding-top: 56.25%; /* 16:9 Aspect Ratio */
    background-color: rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

.course-card .course-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.course-card:hover .course-thumbnail img {
    transform: scale(1.05);
}

.course-card .course-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.course-card:hover .course-overlay {
    opacity: 1;
}

.course-card .course-content {
    padding: 1.5rem;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.course-card .course-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    line-height: 1.4;
}

.course-card .course-title a {
    color: var(--text-primary);
    text-decoration: none;
    transition: color var(--transition-normal);
}

.course-card .course-title a:hover {
    color: var(--primary-color);
}

.course-card .course-description {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1rem;
    flex-grow: 1;
}

.course-card .course-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
    color: var(--text-muted);
    font-size: 0.85rem;
}

.course-header {
    background: var(--card-bg);
    border-radius: 16px;
    padding: 2rem;
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
}

.course-sidebar {
    position: sticky;
    top: 2rem;
}

.course-info {
    margin: 0;
    padding: 0;
}

.course-info li {
    display: flex;
    align-items: center;
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.course-info li:last-child {
    margin-bottom: 0;
}

.course-info i {
    width: 24px;
    color: var(--primary-color);
}