* {
    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: 1000;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
}

.nav-brand {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: #6366f1;
    font-weight: 700;
    font-size: 1.25rem;
}

.logo {
    width: 32px;
    height: 32px;
    margin-right: 0.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: #6b7280;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-link:hover,
.nav-link.active {
    color: #6366f1;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: #333;
    margin: 2px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 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-actions {
    display: flex;
    gap: 1rem;
}

.hero-img {
    width: 100%;
    max-width: 500px;
    height: auto;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    text-decoration: none;
    border-radius: 0.5rem;
    font-weight: 600;
    text-align: center;
    transition: all 0.2s;
    cursor: pointer;
    border: 2px solid transparent;
}

.btn-primary {
    background: #6366f1;
    color: white;
}

.btn-primary:hover {
    background: #5856eb;
    transform: translateY(-1px);
}

.btn-secondary {
    background: transparent;
    color: white;
    border-color: white;
}

.btn-secondary:hover {
    background: white;
    color: #6366f1;
}

/* Features Section */
.features {
    padding: 4rem 0;
    background: #f9fafb;
}

.features h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: #1f2937;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2rem;
    border-radius: 1rem;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.2s;
}

.feature-card:hover {
    transform: translateY(-4px);
}

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

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #1f2937;
}

.feature-card p {
    color: #6b7280;
}

/* Featured Courses */
.featured-courses {
    padding: 4rem 0;
}

.featured-courses h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: #1f2937;
}

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

.course-card {
    background: white;
    border-radius: 1rem;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.2s;
}

.course-card:hover {
    transform: translateY(-4px);
}

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

.course-content {
    padding: 1.5rem;
}

.course-category {
    display: inline-block;
    background: #e0e7ff;
    color: #6366f1;
    padding: 0.25rem 0.75rem;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.course-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1f2937;
}

.course-description {
    color: #6b7280;
    margin-bottom: 1rem;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: #6b7280;
}

.course-price {
    font-size: 1.5rem;
    font-weight: 700;
    color: #059669;
    margin-bottom: 1rem;
}

.course-link {
    display: block;
    text-align: center;
    background: #6366f1;
    color: white;
    padding: 0.75rem;
    text-decoration: none;
    border-radius: 0.5rem;
    font-weight: 600;
    transition: background 0.2s;
}

.course-link:hover {
    background: #5856eb;
}

.section-actions {
    text-align: center;
}

/* Course Details Page */
.course-hero {
    background: #1f2937;
    color: white;
    padding: 3rem 0;
}

.course-hero-content {
    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-bottom: 1.5rem;
    font-size: 0.875rem;
}

.course-hero-sidebar {
    background: rgba(255,255,255,0.1);
    padding: 2rem;
    border-radius: 1rem;
}

.course-hero-price {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
}

.course-details {
    padding: 4rem 0;
}

.course-details-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
}

.course-section {
    margin-bottom: 3rem;
}

.course-section h2 {
    font-size: 1.75rem;
    margin-bottom: 1rem;
    color: #1f2937;
}

.course-section h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: #1f2937;
}

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

.course-section li {
    padding: 0.5rem 0;
    border-bottom: 1px solid #e5e7eb;
}

.course-section li:before {
    content: "✓";
    color: #059669;
    font-weight: bold;
    margin-right: 0.5rem;
}

.curriculum-item {
    background: #f9fafb;
    padding: 1rem;
    margin-bottom: 0.5rem;
    border-radius: 0.5rem;
}

.instructor-card {
    background: #f9fafb;
    padding: 2rem;
    border-radius: 1rem;
}

.instructor-name {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1f2937;
}

.faq-item {
    border-bottom: 1px solid #e5e7eb;
    padding: 1rem 0;
}

.faq-question {
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1f2937;
}

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

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: #374151;
}

.form-input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #d1d5db;
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-input:focus {
    outline: none;
    border-color: #6366f1;
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-textarea {
    min-height: 120px;
    resize: vertical;
}

.form-checkbox {
    margin-right: 0.5rem;
}

.form-error {
    color: #dc2626;
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

.form-success {
    color: #059669;
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

/* Checkout */
.checkout {
    padding: 3rem 0;
    background: #f9fafb;
}

.checkout-container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    padding: 3rem;
    border-radius: 1rem;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.checkout-steps {
    display: flex;
    justify-content: center;
    margin-bottom: 3rem;
}

.step {
    display: flex;
    align-items: center;
    padding: 0.5rem 1rem;
    background: #e5e7eb;
    color: #6b7280;
    border-radius: 2rem;
    margin: 0 0.5rem;
}

.step.active {
    background: #6366f1;
    color: white;
}

.step.completed {
    background: #059669;
    color: white;
}

.order-summary {
    background: #f9fafb;
    padding: 2rem;
    border-radius: 1rem;
    margin-bottom: 2rem;
}

.summary-item {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid #e5e7eb;
}

.summary-total {
    font-size: 1.25rem;
    font-weight: 700;
    color: #1f2937;
}

.payment-icons {
    display: flex;
    gap: 1rem;
    align-items: center;
    margin-bottom: 2rem;
}

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

/* Footer */
.footer {
    background: #1f2937;
    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 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: white;
}

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

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

.footer-section a {
    color: #d1d5db;
    text-decoration: none;
    transition: color 0.2s;
}

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: #d1d5db;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0,0,0,0.05);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }

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

    .hero-actions {
        justify-content: center;
        flex-wrap: wrap;
    }

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

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

    .course-hero-content {
        grid-template-columns: 1fr;
    }

    .course-details-content {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    .hero {
        padding: 2rem 0;
    }

    .hero-content h1 {
        font-size: 1.75rem;
    }

    .features {
        padding: 2rem 0;
    }

    .featured-courses {
        padding: 2rem 0;
    }

    .checkout-container {
        padding: 1.5rem;
        margin: 0 15px;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus styles */
a:focus,
button:focus,
input:focus,
textarea:focus,
select:focus {
    outline: 2px solid #6366f1;
    outline-offset: 2px;
}