/* ============================================
   GLOBAL STYLES
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2563eb;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --info-color: #06b6d4;
    --dark-color: #1e293b;
    --light-color: #f8fafc;
    --border-color: #e2e8f0;
    --text-color: #334155;
    --text-muted: #64748b;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    color: var(--text-color);
    line-height: 1.6;
    background-color: var(--light-color);
}

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

.container-fluid {
    max-width: 100%;
    padding: 0 20px;
}

/* ============================================
   NAVIGATION BAR
   ============================================ */
.navbar {
    background-color: white;
    box-shadow: var(--shadow);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.navbar-menu {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.nav-link {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

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

.nav-user-menu {
    position: relative;
}

.nav-user-button {
    background: none;
    border: none;
    color: var(--text-color);
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    transition: background-color 0.3s;
}

.nav-user-button:hover {
    background-color: var(--light-color);
}

.nav-dropdown {
    position: absolute;
    top: 100%;
    right: 0;
    background: white;
    box-shadow: var(--shadow-lg);
    border-radius: 0.5rem;
    margin-top: 0.5rem;
    min-width: 200px;
    display: none;
}

.nav-user-menu:hover .nav-dropdown {
    display: block;
}

.nav-dropdown a {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--text-color);
    text-decoration: none;
    transition: background-color 0.3s;
}

.nav-dropdown a:hover {
    background-color: var(--light-color);
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
    display: inline-block;
    padding: 0.625rem 1.25rem;
    border: none;
    border-radius: 0.5rem;
    font-weight: 500;
    text-decoration: none;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: #1d4ed8;
}

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

.btn-secondary:hover {
    background-color: #475569;
}

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

.btn-success:hover {
    background-color: #059669;
}

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

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

.btn-sm {
    padding: 0.375rem 0.75rem;
    font-size: 0.875rem;
}

.btn-lg {
    padding: 0.875rem 1.75rem;
    font-size: 1.125rem;
}

.btn-block {
    display: block;
    width: 100%;
}

/* ============================================
   FLASH MESSAGES
   ============================================ */
.flash-messages-container {
    position: fixed;
    top: 80px;
    right: 20px;
    z-index: 9999;
    max-width: 400px;
}

.alert {
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-lg);
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

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

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

.alert-warning {
    background-color: #fef3c7;
    color: #92400e;
    border-left: 4px solid var(--warning-color);
}

.alert-info {
    background-color: #dbeafe;
    color: #1e40af;
    border-left: 4px solid var(--info-color);
}

.alert-close {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.25rem;
    color: inherit;
    opacity: 0.7;
}

.alert-close:hover {
    opacity: 1;
}

/* ============================================
   MAIN CONTENT
   ============================================ */
.main-content {
    min-height: calc(100vh - 200px);
    padding: 2rem 0;
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero-section {
    background: linear-gradient(135deg, var(--primary-color), #1d4ed8);
    color: white;
    padding: 5rem 0;
    text-align: center;
}

.hero-content h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.hero-content p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

/* ============================================
   FEATURES SECTION
   ============================================ */
.features-section {
    padding: 4rem 0;
}

.section-title {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 3rem;
    color: var(--dark-color);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.feature-card {
    text-align: center;
    padding: 2rem;
    background: white;
    border-radius: 0.5rem;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}

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

.feature-icon {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

/* ============================================
   COURSES GRID
   ============================================ */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.course-card {
    background: white;
    border-radius: 0.5rem;
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
}

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

.course-card-header {
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--light-color);
}

.course-category {
    background-color: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.875rem;
}

.course-level {
    background-color: var(--secondary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.875rem;
    text-transform: capitalize;
}

.course-card-body {
    padding: 1.5rem;
}

.course-card-body h3 {
    color: var(--dark-color);
    margin-bottom: 0.5rem;
    font-size: 1.25rem;
}

.course-code {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
}

.course-description {
    color: var(--text-color);
    margin-bottom: 1rem;
    line-height: 1.5;
}

.course-instructor {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
}

.course-meta {
    display: flex;
    gap: 1rem;
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-top: 1rem;
}

.course-card-footer {
    padding: 1rem 1.5rem;
    background-color: var(--light-color);
    display: flex;
    gap: 0.5rem;
    justify-content: space-between;
}

/* ============================================
   PROGRESS BAR
   ============================================ */
.progress-section {
    margin-top: 1rem;
}

.progress-info {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
    font-size: 0.875rem;
}

.progress-percentage {
    font-weight: bold;
    color: var(--primary-color);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background-color: var(--border-color);
    border-radius: 1rem;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: var(--success-color);
    transition: width 0.3s;
}

/* ============================================
   BADGES
   ============================================ */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.875rem;
    font-weight: 500;
}

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

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

.badge-warning {
    background-color: #fef3c7;
    color: #92400e;
}

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

.badge-secondary {
    background-color: var(--border-color);
    color: var(--text-color);
}

/* ============================================
   EMPTY STATE
   ============================================ */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    background: white;
    border-radius: 0.5rem;
    box-shadow: var(--shadow);
}

.empty-state i {
    font-size: 4rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.empty-state h3 {
    color: var(--dark-color);
    margin-bottom: 0.5rem;
}

.empty-state p {
    color: var(--text-muted);
    margin-bottom: 1.5rem;
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    background-color: var(--dark-color);
    color: white;
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3, .footer-section h4 {
    margin-bottom: 1rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* ============================================
   ERROR PAGES
   ============================================ */
.error-container {
    text-align: center;
    padding: 4rem 2rem;
    min-height: 60vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.error-container h1 {
    font-size: 6rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.error-container h2 {
    font-size: 2rem;
    color: var(--dark-color);
    margin-bottom: 1rem;
}

.error-container p {
    color: var(--text-muted);
    margin-bottom: 2rem;
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */
@media (max-width: 768px) {
    .navbar-menu {
        flex-direction: column;
        gap: 0.5rem;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .courses-grid {
        grid-template-columns: 1fr;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }
}