/**
 * Biology Lovers - Main Stylesheet
 * Theme: Black & Red Biology-inspired Dark Theme
 */

/* ============================================
   CSS Variables & Root Styles
   ============================================ */
:root {
    /* Primary Colors */
    --primary-black: #000000;
    --primary-red: #E63946;
    --primary-red-dark: #C1121F;
    --primary-red-light: #FF6B6B;
    
    /* Background Colors */
    --bg-dark: #0a0a0a;
    --bg-darker: #050505;
    --bg-card: #111111;
    --bg-card-hover: #1a1a1a;
    --bg-gradient: linear-gradient(135deg, #0a0a0a 0%, #1a0000 100%);
    
    /* Text Colors */
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --text-muted: #666666;
    --text-red: #FF6B6B;
    
    /* Border Colors */
    --border-dark: #222222;
    --border-red: rgba(192, 0, 0, 0.3);
    
    /* Status Colors */
    --success: #28a745;
    --warning: #ffc107;
    --danger: #dc3545;
    --info: #17a2b8;
    
    /* Font Family */
    --font-bangla: 'Hind Siliguri', 'Noto Sans Bengali', sans-serif;
    --font-heading: 'Hind Siliguri', sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 20px;
    --radius-full: 50%;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
    --shadow-red: 0 4px 20px rgba(192, 0, 0, 0.3);
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ============================================
   Base Styles
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-bangla);
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-darker);
}

::-webkit-scrollbar-thumb {
    background: var(--primary-red);
    border-radius: var(--radius-sm);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-red-light);
}

/* Selection */
::selection {
    background: var(--primary-red);
    color: var(--text-primary);
}

/* ============================================
   Typography
   ============================================ */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.75rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

a {
    color: var(--primary-red-light);
    text-decoration: none;
    transition: var(--transition-fast);
}

a:hover {
    color: var(--text-primary);
}

/* ============================================
   Layout Components
   ============================================ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section {
    padding: var(--spacing-xxl) 0;
}

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.section-title h2 {
    font-size: 2.5rem;
    position: relative;
    display: inline-block;
}

.section-title h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: var(--primary-red);
    border-radius: var(--radius-sm);
}

.section-title p {
    margin-top: var(--spacing-lg);
    font-size: 1.1rem;
}

/* ============================================
   Navbar
   ============================================ */
.navbar {
    background: rgba(0, 0, 0, 0.95);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md) 0;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid var(--border-dark);
    transition: var(--transition-normal);
}

.navbar.scrolled {
    background: rgba(0, 0, 0, 0.98);
    box-shadow: var(--shadow-md);
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.navbar-brand img {
    height: 45px;
}

.navbar-brand span {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.navbar-brand .text-red {
    color: var(--primary-red);
}

.navbar-nav .nav-link {
    color: var(--text-secondary);
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    position: relative;
    transition: var(--transition-fast);
}

.navbar-nav .nav-link:hover,
.navbar-nav .nav-link.active {
    color: var(--text-primary);
}

.navbar-nav .nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--primary-red);
    transition: var(--transition-normal);
    transform: translateX(-50%);
}

.navbar-nav .nav-link:hover::after,
.navbar-nav .nav-link.active::after {
    width: 80%;
}

.navbar-toggler {
    border: none;
    padding: var(--spacing-sm);
}

.navbar-toggler:focus {
    box-shadow: none;
}

.navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba%28255, 255, 255, 0.8%29' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    font-family: var(--font-bangla);
    font-weight: 600;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    transition: var(--transition-normal);
    border: none;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.btn-primary {
    background: var(--primary-red);
    color: var(--text-primary);
}

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

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary-red);
    color: var(--primary-red);
}

.btn-outline:hover {
    background: var(--primary-red);
    color: var(--text-primary);
}

.btn-dark {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border-dark);
}

.btn-dark:hover {
    background: var(--bg-card-hover);
    border-color: var(--primary-red);
}

.btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1.1rem;
}

.btn-sm {
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: 0.9rem;
}

.btn-block {
    width: 100%;
}

/* ============================================
   Cards
   ============================================ */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition-normal);
}

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

.card-img-top {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.card-body {
    padding: var(--spacing-lg);
}

.card-title {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
}

.card-text {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-gradient);
    position: relative;
    overflow: hidden;
    padding-top: 80px;
    text-align: center;
}

/* Hero background - clean */

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--spacing-lg);
}

.hero-title .highlight {
    color: var(--primary-red);
    position: relative;
}

.hero-subtitle {
    font-size: 1.3rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    justify-content: center;
}

.hero-image {
    position: relative;
}

.hero-image img {
    max-width: 100%;
}

/* DNA Animation - removed */
.dna-helix {
    display: none;
}

/* Biology decorative elements */
.bio-decoration {
    position: absolute;
    opacity: 0.05;
    pointer-events: none;
}

.bio-decoration.cell {
    width: 100px;
    height: 100px;
    border: 2px solid var(--primary-red);
    border-radius: 50%;
}

.bio-decoration.dna {
    font-size: 80px;
}

/* ============================================
   Stats Section
   ============================================ */
.stats-section {
    background: var(--bg-darker);
    padding: var(--spacing-xxl) 0;
    border-top: 1px solid var(--border-dark);
    border-bottom: 1px solid var(--border-dark);
}

.stat-card {
    text-align: center;
    padding: var(--spacing-xl);
}

.stat-icon {
    width: 70px;
    height: 70px;
    background: rgba(192, 0, 0, 0.2);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-md);
    font-size: 1.8rem;
    color: var(--primary-red);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* Counter Animation */
.counter {
    display: inline-block;
}

/* ============================================
   Course Cards
   ============================================ */
.course-card {
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition-normal);
    height: 100%;
}

.course-card:hover {
    transform: translateY(-8px);
    border-color: var(--primary-red);
    box-shadow: var(--shadow-red);
}

.course-card-image {
    position: relative;
    height: 180px;
    overflow: hidden;
}

.course-card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition-slow);
}

.course-card:hover .course-card-image img {
    transform: scale(1.1);
}

.course-badge {
    position: absolute;
    top: var(--spacing-md);
    left: var(--spacing-md);
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--primary-red);
    color: var(--text-primary);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

.course-badge.online {
    background: var(--info);
}

.course-badge.offline {
    background: var(--success);
}

.course-card-body {
    padding: var(--spacing-lg);
}

.course-category {
    color: var(--primary-red);
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.course-title {
    font-size: 1.2rem;
    margin-bottom: var(--spacing-sm);
}

.course-meta {
    display: flex;
    gap: var(--spacing-md);
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-md);
}

.course-meta i {
    color: var(--primary-red);
    margin-right: var(--spacing-xs);
}

.course-price {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-dark);
}

.course-price .price {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--primary-red);
}

.course-price .old-price {
    text-decoration: line-through;
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-left: var(--spacing-sm);
}

/* ============================================
   Testimonials
   ============================================ */
.testimonials-section {
    background: var(--bg-gradient);
    position: relative;
}

.testimonial-card {
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin: var(--spacing-md);
    position: relative;
}

.testimonial-card::before {
    content: '"';
    position: absolute;
    top: 20px;
    right: 30px;
    font-size: 5rem;
    color: var(--primary-red);
    opacity: 0.2;
    font-family: Georgia, serif;
    line-height: 1;
}

/* Avatar hidden - using quote icon instead */
.testimonial-avatar {
    display: none;
}

.quote-icon {
    font-size: 2.5rem;
    color: var(--primary-red);
    margin-bottom: 15px;
    opacity: 0.5;
}

.testimonial-content {
    font-size: 1.05rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.8;
}

.testimonial-author {
    font-weight: 700;
    color: var(--text-primary);
}

.testimonial-designation {
    color: var(--primary-red);
    font-size: 0.9rem;
}

.testimonial-rating {
    color: #ffc107;
    margin-top: var(--spacing-sm);
}

/* Swiper Customization */
.swiper-pagination-bullet {
    background: var(--text-muted);
    opacity: 1;
}

.swiper-pagination-bullet-active {
    background: var(--primary-red);
}

/* ============================================
   FAQ Section
   ============================================ */
.faq-section {
    background: var(--bg-darker);
}

.faq-item {
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    overflow: hidden;
    transition: var(--transition-normal);
}

.faq-item:hover {
    border-color: var(--border-red);
}

.faq-item.active {
    border-color: var(--primary-red);
}

.faq-question {
    padding: var(--spacing-lg);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 600;
    transition: var(--transition-fast);
}

.faq-question:hover {
    color: var(--primary-red);
}

.faq-question i {
    transition: var(--transition-normal);
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
}

.faq-answer {
    padding: 0 var(--spacing-lg) var(--spacing-lg);
    color: var(--text-secondary);
    display: none;
    animation: fadeIn 0.3s ease;
}

.faq-item.active .faq-answer {
    display: block;
}

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

/* ============================================
   Footer
   ============================================ */
.footer {
    background: var(--primary-black);
    padding: var(--spacing-xxl) 0 var(--spacing-lg);
    border-top: 1px solid var(--border-dark);
}

.footer-brand {
    margin-bottom: var(--spacing-lg);
}

.footer-brand img {
    height: 50px;
    margin-bottom: var(--spacing-md);
}

.footer-description {
    color: var(--text-secondary);
    max-width: 300px;
}

.footer-title {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    position: relative;
    padding-bottom: var(--spacing-sm);
}

.footer-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 2px;
    background: var(--primary-red);
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    color: var(--text-secondary);
    transition: var(--transition-fast);
}

.footer-links a:hover {
    color: var(--primary-red);
    padding-left: var(--spacing-sm);
}

.footer-contact li {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

.footer-contact i {
    color: var(--primary-red);
    margin-top: 4px;
}

.social-links {
    display: flex;
    gap: var(--spacing-sm);
}

.social-links a {
    width: 40px;
    height: 40px;
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    transition: var(--transition-normal);
}

.social-links a:hover {
    background: var(--primary-red);
    border-color: var(--primary-red);
    color: var(--text-primary);
    transform: translateY(-3px);
}

.footer-bottom {
    margin-top: var(--spacing-xxl);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border-dark);
    text-align: center;
    color: var(--text-muted);
}

/* ============================================
   Forms
   ============================================ */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
    color: var(--text-secondary);
}

.form-control {
    width: 100%;
    padding: var(--spacing-md);
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-bangla);
    font-size: 1rem;
    transition: var(--transition-fast);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-red);
    box-shadow: 0 0 0 3px rgba(192, 0, 0, 0.2);
}

.form-control::placeholder {
    color: var(--text-muted);
}

.form-control.is-invalid {
    border-color: var(--danger);
}

.invalid-feedback {
    color: var(--danger);
    font-size: 0.85rem;
    margin-top: var(--spacing-xs);
}

.password-toggle {
    position: relative;
}

.password-toggle .toggle-btn {
    position: absolute;
    right: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: var(--spacing-xs);
}

.password-toggle .toggle-btn:hover {
    color: var(--primary-red);
}

/* ============================================
   Auth Pages
   ============================================ */
.auth-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xl);
    background: var(--bg-gradient);
}

.auth-card {
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xxl);
    width: 100%;
    max-width: 450px;
    position: relative;
    overflow: hidden;
}

.auth-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-red);
}

.auth-logo {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.auth-logo img {
    height: 60px;
}

.auth-title {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.auth-title h1 {
    font-size: 1.75rem;
    margin-bottom: var(--spacing-xs);
}

.auth-title p {
    color: var(--text-secondary);
}

.auth-divider {
    display: flex;
    align-items: center;
    margin: var(--spacing-lg) 0;
    color: var(--text-muted);
}

.auth-divider::before,
.auth-divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border-dark);
}

.auth-divider span {
    padding: 0 var(--spacing-md);
}

.auth-footer {
    text-align: center;
    margin-top: var(--spacing-lg);
    color: var(--text-secondary);
}

/* ============================================
   Dashboard Layout
   ============================================ */
.dashboard-wrapper {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: 260px;
    background: var(--bg-darker);
    border-right: 1px solid var(--border-dark);
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    z-index: 100;
    transition: var(--transition-normal);
    overflow-y: auto;
}

.sidebar-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-dark);
}

.sidebar-menu {
    padding: var(--spacing-md);
}

.sidebar-menu-item {
    margin-bottom: var(--spacing-xs);
}

.sidebar-menu-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    transition: var(--transition-fast);
}

.sidebar-menu-link:hover,
.sidebar-menu-link.active {
    background: rgba(192, 0, 0, 0.15);
    color: var(--primary-red);
}

.sidebar-menu-link i {
    width: 20px;
    text-align: center;
}

.sidebar-divider {
    height: 1px;
    background: var(--border-dark);
    margin: var(--spacing-md) 0;
}

.main-content {
    flex: 1;
    margin-left: 260px;
    padding: var(--spacing-xl);
    background: var(--bg-dark);
}

.dashboard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border-dark);
}

.dashboard-title h1 {
    font-size: 1.75rem;
    margin-bottom: var(--spacing-xs);
}

.dashboard-title p {
    color: var(--text-secondary);
    margin: 0;
}

.dashboard-card {
    background: var(--bg-card);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.dashboard-card-title {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border-dark);
}

/* ============================================
   Tables
   ============================================ */
.table-responsive {
    overflow-x: auto;
}

.table {
    width: 100%;
    border-collapse: collapse;
}

.table th,
.table td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid var(--border-dark);
}

.table th {
    background: var(--bg-darker);
    font-weight: 600;
    color: var(--text-secondary);
}

.table tr:hover td {
    background: var(--bg-card-hover);
}

/* ============================================
   Badges
   ============================================ */
.badge {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
}

.badge-primary {
    background: var(--primary-red);
    color: var(--text-primary);
}

.badge-success {
    background: var(--success);
    color: var(--text-primary);
}

.badge-warning {
    background: var(--warning);
    color: var(--primary-black);
}

.badge-danger {
    background: var(--danger);
    color: var(--text-primary);
}

.badge-info {
    background: var(--info);
    color: var(--text-primary);
}

/* ============================================
   Progress Bar
   ============================================ */
.progress {
    height: 10px;
    background: var(--bg-darker);
    border-radius: var(--radius-sm);
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: var(--primary-red);
    border-radius: var(--radius-sm);
    transition: width 0.5s ease;
}

/* ============================================
   Alerts
   ============================================ */
.alert {
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.alert-success {
    background: rgba(40, 167, 69, 0.15);
    border: 1px solid var(--success);
    color: var(--success);
}

.alert-danger {
    background: rgba(220, 53, 69, 0.15);
    border: 1px solid var(--danger);
    color: var(--danger);
}

.alert-warning {
    background: rgba(255, 193, 7, 0.15);
    border: 1px solid var(--warning);
    color: var(--warning);
}

.alert-info {
    background: rgba(23, 162, 184, 0.15);
    border: 1px solid var(--info);
    color: var(--info);
}

/* ============================================
   Animations
   ============================================ */
[data-aos] {
    opacity: 0;
    transition-property: opacity, transform;
}

[data-aos].aos-animate {
    opacity: 1;
}

[data-aos="fade-up"] {
    transform: translateY(30px);
}

[data-aos="fade-up"].aos-animate {
    transform: translateY(0);
}

[data-aos="fade-down"] {
    transform: translateY(-30px);
}

[data-aos="fade-down"].aos-animate {
    transform: translateY(0);
}

[data-aos="fade-left"] {
    transform: translateX(30px);
}

[data-aos="fade-left"].aos-animate {
    transform: translateX(0);
}

[data-aos="fade-right"] {
    transform: translateX(-30px);
}

[data-aos="fade-right"].aos-animate {
    transform: translateX(0);
}

[data-aos="zoom-in"] {
    transform: scale(0.9);
}

[data-aos="zoom-in"].aos-animate {
    transform: scale(1);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 991px) {
    .sidebar {
        transform: translateX(-100%);
    }
    
    .sidebar.show {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    /* Mobile Navbar */
    .navbar-collapse {
        position: fixed;
        top: 0;
        left: -100%;
        width: 280px;
        height: 100vh;
        background: var(--bg-darker);
        border-right: 1px solid var(--border-dark);
        padding: 80px 20px 30px;
        transition: left 0.3s ease;
        z-index: 1000;
        overflow-y: auto;
    }
    
    .navbar-collapse.show {
        left: 0;
    }
    
    .navbar-collapse .navbar-nav {
        flex-direction: column;
        width: 100%;
    }
    
    .navbar-collapse .nav-item {
        border-bottom: 1px solid var(--border-dark);
    }
    
    .navbar-collapse .nav-link {
        padding: 15px 0;
        font-size: 1.1rem;
    }
    
    .navbar-collapse .nav-link::after {
        display: none;
    }
    
    .navbar-collapse .nav-buttons {
        flex-direction: column;
        margin-top: 20px;
        width: 100%;
    }
    
    .navbar-collapse .nav-buttons .btn {
        width: 100%;
        margin-bottom: 10px;
    }
    
    .navbar-toggler {
        position: relative;
        z-index: 1001;
        background: var(--bg-card);
        border-radius: var(--radius-md);
        padding: 10px 12px;
    }
    
    /* Mobile Nav Overlay */
    .navbar-collapse::before {
        content: '';
        position: fixed;
        top: 0;
        left: 280px;
        width: calc(100vw - 280px);
        height: 100vh;
        background: rgba(0,0,0,0.7);
        opacity: 0;
        visibility: hidden;
        transition: opacity 0.3s ease;
    }
    
    .navbar-collapse.show::before {
        opacity: 1;
        visibility: visible;
    }
}

@media (max-width: 767px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.1rem;
    }
    
    .section {
        padding: var(--spacing-xl) 0;
    }
    
    .section-title h2 {
        font-size: 1.75rem;
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .auth-card {
        padding: var(--spacing-xl);
    }
    
    /* Courses page filter */
    .course-filters {
        padding: 15px;
    }
    
    .filter-tabs {
        flex-direction: column;
        gap: 10px;
    }
    
    .filter-tabs .btn-group {
        width: 100%;
        flex-wrap: wrap;
    }
    
    .filter-tabs .btn {
        flex: 1;
        font-size: 0.85rem;
        padding: 6px 10px;
    }
}

@media (max-width: 575px) {
    .hero-buttons {
        flex-direction: column;
    }
    
    .hero-buttons .btn {
        width: 100%;
    }
    
    .dashboard-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-md);
    }
    
    .navbar-brand img {
        height: 40px;
    }
}

/* ============================================
   Utility Classes
   ============================================ */
.text-red { color: var(--primary-red) !important; }
.text-white { color: var(--text-primary) !important; }
.text-muted { color: var(--text-muted) !important; }
.text-secondary { color: var(--text-secondary) !important; }

.bg-dark { background: var(--bg-dark) !important; }
.bg-darker { background: var(--bg-darker) !important; }
.bg-card { background: var(--bg-card) !important; }
.bg-red { background: var(--primary-red) !important; }

.border-red { border-color: var(--primary-red) !important; }
.border-dark { border-color: var(--border-dark) !important; }

.rounded { border-radius: var(--radius-md) !important; }
.rounded-lg { border-radius: var(--radius-lg) !important; }
.rounded-full { border-radius: var(--radius-full) !important; }

.shadow { box-shadow: var(--shadow-md) !important; }
.shadow-red { box-shadow: var(--shadow-red) !important; }

.mb-0 { margin-bottom: 0 !important; }
.mt-0 { margin-top: 0 !important; }
.py-0 { padding-top: 0 !important; padding-bottom: 0 !important; }

/* Loading Spinner */
.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-dark);
    border-top-color: var(--primary-red);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Page Loader - Hidden by default */
.page-loader {
    display: none;
}

/* Login Button Style */
.btn-login {
    background: #333333;
    color: #ffffff;
    border: 1px solid #444444;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 600;
    transition: var(--transition-normal);
}

.btn-login:hover {
    background: #444444;
    color: #ffffff;
    border-color: #555555;
}

/* Footer Links with icons */
.footer-links li a {
    display: flex;
    align-items: center;
}

.footer-links li a i {
    color: var(--primary-red);
    font-size: 0.7rem;
}

/* Navbar Brand - logo only */
.navbar-brand {
    padding: 0;
}

.navbar-brand img {
    height: 50px;
    max-width: 200px;
    object-fit: contain;
}