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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fff;
}

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

/* Header */
.header {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    padding: 1rem 0;
}

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

.nav-brand a {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: #2563eb;
    font-weight: 700;
    font-size: 1.25rem;
}

.logo {
    width: 32px;
    height: 32px;
    margin-right: 8px;
}

.nav-menu {
    display: flex;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: #64748b;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-link:hover,
.nav-link.active {
    color: #2563eb;
}

.nav-mobile-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
}

.nav-mobile-toggle span {
    width: 25px;
    height: 3px;
    background: #333;
    transition: 0.3s;
}

/* Hero */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 5rem 0;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

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

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    text-align: center;
    transition: all 0.2s;
    border: 2px solid transparent;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: #2563eb;
    color: white;
    border-color: #2563eb;
}

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

.btn-outline {
    background: transparent;
    color: #2563eb;
    border-color: #2563eb;
}

.btn-outline:hover {
    background: #2563eb;
    color: white;
}

.btn-success {
    background: #10b981;
    color: white;
    border-color: #10b981;
}

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

/* Sections */
section {
    padding: 4rem 0;
}

.featured-courses {
    background: #f8fafc;
}

.featured-courses h2,
.features h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: #1e293b;
}

/* Course Grid */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.course-card {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    overflow: hidden;
    transition: transform 0.2s, box-shadow 0.2s;
    text-decoration: none;
    color: inherit;
}

.course-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}

.course-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.course-content {
    padding: 1.5rem;
}

.course-category {
    display: inline-block;
    background: #dbeafe;
    color: #2563eb;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 1rem;
}

.course-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1e293b;
}

.course-description {
    color: #64748b;
    margin-bottom: 1rem;
    line-height: 1.5;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.875rem;
    color: #64748b;
    margin-bottom: 1rem;
}

.course-price {
    font-size: 1.5rem;
    font-weight: 700;
    color: #2563eb;
}

/* Features */
.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: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: #1e293b;
}

/* Course Details */
.course-hero {
    background: #1e293b;
    color: white;
    padding: 3rem 0;
}

.course-hero .container {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    align-items: start;
}

.course-hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.course-hero-meta {
    display: flex;
    gap: 2rem;
    margin: 1rem 0;
    font-size: 0.875rem;
}

.course-hero-meta span {
    background: rgba(255,255,255,0.2);
    padding: 4px 12px;
    border-radius: 20px;
}

.course-sidebar {
    background: white;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    position: sticky;
    top: 100px;
}

.course-sidebar img {
    width: 100%;
    border-radius: 8px;
    margin-bottom: 1rem;
}

.course-sidebar .course-price {
    font-size: 2rem;
    margin-bottom: 1rem;
    text-align: center;
}

.course-content-section {
    margin: 3rem 0;
}

.course-content-section h2 {
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
    color: #1e293b;
}

.course-content-section ul {
    list-style: none;
    padding: 0;
}

.course-content-section li {
    padding: 0.5rem 0;
    border-bottom: 1px solid #e2e8f0;
    position: relative;
    padding-left: 1.5rem;
}

.course-content-section li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: #10b981;
    font-weight: bold;
}

.curriculum-item {
    background: #f8fafc;
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 0.5rem;
    border-left: 4px solid #2563eb;
}

.faq-item {
    background: white;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    margin-bottom: 1rem;
}

.faq-question {
    padding: 1rem;
    cursor: pointer;
    font-weight: 600;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-answer {
    padding: 0 1rem 1rem;
    color: #64748b;
    display: none;
}

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

/* Forms */
.form-section {
    padding: 3rem 0;
    background: #f8fafc;
}

.form-container {
    max-width: 600px;
    margin: 0 auto;
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #374151;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #2563eb;
}

.form-group.error input,
.form-group.error select {
    border-color: #ef4444;
}

.form-error {
    color: #ef4444;
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

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

.checkbox-group {
    display: flex;
    align-items: start;
    gap: 0.5rem;
}

.checkbox-group input[type="checkbox"] {
    width: auto;
    margin: 0;
}

.checkout-summary {
    background: #f8fafc;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 2rem;
}

.summary-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
}

.summary-total {
    font-weight: 700;
    font-size: 1.25rem;
    border-top: 2px solid #e5e7eb;
    padding-top: 0.5rem;
    margin-top: 1rem;
}

.payment-icons {
    display: flex;
    gap: 0.5rem;
    align-items: center;
    margin: 1rem 0;
}

.payment-icons svg {
    width: 40px;
    height: 25px;
}

/* Filters */
.filters {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.filters-row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 200px;
    gap: 1rem;
    align-items: end;
}

/* Footer */
.footer {
    background: #1e293b;
    color: white;
    padding: 3rem 0 1rem;
}

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

.footer-section h4 {
    margin-bottom: 1rem;
    color: white;
}

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

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

.footer-section a {
    color: #94a3b8;
    text-decoration: none;
    transition: color 0.2s;
}

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

.footer-bottom {
    border-top: 1px solid #374151;
    padding-top: 1rem;
    text-align: center;
    color: #94a3b8;
}

/* Utilities */
.text-center {
    text-align: center;
}

.mb-2 {
    margin-bottom: 1rem;
}

.success-message {
    background: #dcfce7;
    color: #166534;
    padding: 1rem;
    border-radius: 8px;
    border: 1px solid #bbf7d0;
    margin-bottom: 2rem;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .nav-mobile-toggle {
        display: flex;
    }
    
    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .courses-grid {
        grid-template-columns: 1fr;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .course-hero .container {
        grid-template-columns: 1fr;
    }
    
    .filters-row {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 3rem 0;
    }
    
    section {
        padding: 2rem 0;
    }
    
    .course-card {
        margin-bottom: 1rem;
    }
}