/* CourseHub - Modern Course Platform Styles */
:root {
    --primary: #2D5BFF;
    --primary-dark: #1E3FCC;
    --secondary: #FF6B35;
    --dark: #1A1A2E;
    --dark-alt: #16213E;
    --light: #F8F9FA;
    --white: #FFFFFF;
    --success: #10B981;
    --warning: #F59E0B;
    --danger: #EF4444;
    --text-dark: #2C3E50;
    --text-light: #6C757D;
    --border: #E5E7EB;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-lg: rgba(0, 0, 0, 0.2);
}

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

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

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

/* Header & Navigation */
header {
    background: var(--white);
    box-shadow: 0 2px 10px var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--primary);
    text-decoration: none;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

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

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: var(--white);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(45, 91, 255, 0.3);
}

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

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

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--dark) 0%, var(--dark-alt) 100%);
    color: var(--white);
    padding: 6rem 0;
    text-align: center;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    font-weight: 800;
    line-height: 1.2;
}

.hero p {
    font-size: 1.3rem;
    margin-bottom: 2rem;
    color: rgba(255, 255, 255, 0.9);
}

/* Course Grid */
.courses-section {
    padding: 4rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.section-header p {
    color: var(--text-light);
    font-size: 1.1rem;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
}

.course-card {
    background: var(--white);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 15px var(--shadow);
    transition: all 0.3s ease;
    cursor: pointer;
}

.course-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 10px 30px var(--shadow-lg);
}

.course-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
}

.course-content {
    padding: 1.5rem;
}

.course-category {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    background: rgba(45, 91, 255, 0.1);
    color: var(--primary);
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
}

.course-title {
    font-size: 1.4rem;
    margin-bottom: 0.5rem;
    color: var(--dark);
    font-weight: 700;
}

.course-description {
    color: var(--text-light);
    margin-bottom: 1rem;
    line-height: 1.6;
}

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

.course-price {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--primary);
}

.course-level {
    background: var(--light);
    padding: 0.3rem 0.8rem;
    border-radius: 6px;
    font-size: 0.85rem;
    color: var(--text-dark);
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-dark);
}

.form-control {
    width: 100%;
    padding: 0.8rem;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    z-index: 2000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--white);
    padding: 2rem;
    border-radius: 12px;
    max-width: 500px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        transform: translateY(-50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.close-modal {
    position: absolute;
    top: 1rem;
    right: 1rem;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-light);
    background: none;
    border: none;
}

/* Alerts */
.alert {
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
    font-weight: 500;
}

.alert-success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success);
    border-left: 4px solid var(--success);
}

.alert-danger {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger);
    border-left: 4px solid var(--danger);
}

.alert-warning {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning);
    border-left: 4px solid var(--warning);
}

/* Loading Spinner */
.spinner {
    border: 3px solid var(--light);
    border-top: 3px solid var(--primary);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 2rem auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Footer */
footer {
    background: var(--dark);
    color: var(--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 {
    margin-bottom: 1rem;
    color: var(--primary);
}

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

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

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

.footer-links a:hover {
    color: var(--primary);
}

.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);
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    .course-grid {
        grid-template-columns: 1fr;
    }
}