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

:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-white: #ffffff;
    --bg-gray-50: #f9fafb;
    --bg-gray-100: #f3f4f6;
    --border-color: #e5e7eb;
    --border-light: #f3f4f6;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --max-width: 1200px;
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-white);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header Styles */
.header {
    background: var(--bg-white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    padding: 1rem 0;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 1.25rem;
}

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

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.2s;
}

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    transition: all 0.2s;
}

/* Button Styles */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s;
    border: none;
    cursor: pointer;
    font-size: 1rem;
    line-height: 1;
    gap: 0.5rem;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
}

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

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

.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-outline:hover {
    background: var(--bg-gray-50);
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn:disabled:hover {
    transform: none;
}

/* Hero Section */
.hero {
    padding: 4rem 0;
    background: linear-gradient(135deg, var(--bg-gray-50) 0%, var(--bg-white) 100%);
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.hero-content p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.hero-image img {
    width: 100%;
    height: auto;
    border-radius: var(--border-radius-lg);
}

/* Features Section */
.features {
    padding: 4rem 0;
    background: var(--bg-white);
}

.features h2 {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

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

.feature-card {
    text-align: center;
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    background: var(--bg-white);
    border: 1px solid var(--border-light);
    transition: all 0.3s;
}

.feature-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.feature-icon {
    margin-bottom: 1.5rem;
}

.feature-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Featured Courses Section */
.featured-courses {
    padding: 4rem 0;
    background: var(--bg-gray-50);
}

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

.section-header h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.section-header p {
    font-size: 1.25rem;
    color: var(--text-secondary);
}

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

.course-card {
    background: var(--bg-white);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s;
    border: 1px solid var(--border-light);
}

.course-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

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

.course-content {
    padding: 1.5rem;
}

.course-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: var(--text-light);
}

.course-category {
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 500;
}

.course-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    line-height: 1.4;
}

.course-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.course-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.course-price {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

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

/* Trust Section */
.trust-section {
    padding: 3rem 0;
    background: var(--bg-white);
}

.trust-section h2 {
    text-align: center;
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.trust-features {
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.trust-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 500;
    color: var(--text-primary);
}

/* Course Detail Styles */
.course-detail {
    padding: 2rem 0;
}

.course-header {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    margin-bottom: 3rem;
}

.course-info h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.course-sidebar {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-light);
    height: fit-content;
    position: sticky;
    top: 100px;
}

.course-sidebar img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: var(--border-radius);
    margin-bottom: 1.5rem;
}

.sidebar-price {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.sidebar-details {
    margin-bottom: 2rem;
}

.sidebar-details h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.detail-item {
    display: flex;
    justify-content: space-between;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border-light);
}

.detail-item:last-child {
    border-bottom: none;
}

.course-tabs {
    margin-bottom: 2rem;
}

.tab-buttons {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.tab-button {
    background: none;
    border: none;
    padding: 1rem 1.5rem;
    cursor: pointer;
    font-weight: 500;
    color: var(--text-secondary);
    border-bottom: 2px solid transparent;
    transition: all 0.2s;
}

.tab-button.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

.tab-content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.tab-content ul {
    list-style: none;
    margin-bottom: 2rem;
}

.tab-content li {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-light);
    position: relative;
    padding-left: 2rem;
}

.tab-content li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-weight: bold;
}

.curriculum-item {
    background: var(--bg-gray-50);
    padding: 1rem;
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
}

.curriculum-item h4 {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.instructor-section {
    background: var(--bg-gray-50);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    margin-bottom: 2rem;
}

.instructor-section h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.faq-item {
    background: var(--bg-white);
    border: 1px solid var(--border-light);
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    overflow: hidden;
}

.faq-question {
    background: none;
    border: none;
    width: 100%;
    text-align: left;
    padding: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    position: relative;
}

.faq-question:after {
    content: "+";
    position: absolute;
    right: 1.5rem;
    font-size: 1.5rem;
    color: var(--primary-color);
}

.faq-question.active:after {
    content: "−";
}

.faq-answer {
    display: none;
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

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

/* Courses Page Styles */
.courses-header {
    padding: 2rem 0;
    background: var(--bg-gray-50);
}

.courses-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.courses-filters {
    background: var(--bg-white);
    padding: 2rem 0;
    border-bottom: 1px solid var(--border-color);
}

.filters-container {
    display: flex;
    gap: 2rem;
    align-items: center;
    flex-wrap: wrap;
}

.filter-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.filter-group label {
    font-weight: 500;
    color: var(--text-primary);
}

.filter-group input,
.filter-group select {
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
}

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

.courses-results {
    margin-bottom: 2rem;
}

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

/* Checkout Styles */
.checkout-header {
    padding: 2rem 0;
    background: var(--bg-gray-50);
    text-align: center;
}

.checkout-steps {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
}

.step {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    background: var(--bg-white);
    border: 1px solid var(--border-color);
}

.step.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.step.completed {
    background: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
}

.checkout-content {
    padding: 2rem 0;
}

.checkout-container {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
}

.checkout-form {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
}

.checkout-sidebar {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    height: fit-content;
    position: sticky;
    top: 100px;
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

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

.form-row.three-col {
    grid-template-columns: 2fr 1fr 1fr;
}

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

.checkbox-group {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
}

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

.checkbox-group label {
    margin: 0;
    font-weight: normal;
    line-height: 1.5;
}

.order-summary {
    margin-bottom: 2rem;
}

.order-summary h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.summary-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-light);
}

.summary-item:last-child {
    border-bottom: none;
    font-weight: 600;
    font-size: 1.125rem;
    color: var(--primary-color);
}

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

.payment-icon {
    width: 40px;
    height: 24px;
    background: var(--bg-gray-100);
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: bold;
    color: var(--text-secondary);
}

/* Footer Styles */
.footer {
    background: var(--text-primary);
    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 h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.footer-section p {
    color: #d1d5db;
    line-height: 1.6;
    margin-bottom: 1rem;
}

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

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

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

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

.contact-info p {
    margin-bottom: 0.5rem;
    color: #d1d5db;
}

.contact-info a {
    color: #d1d5db;
    text-decoration: none;
}

.contact-info a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid #374151;
    padding-top: 1rem;
    text-align: center;
    color: #9ca3af;
}

/* Content Pages */
.content-page {
    padding: 2rem 0;
    max-width: 800px;
    margin: 0 auto;
}

.content-page h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.content-page h2 {
    font-size: 2rem;
    font-weight: 600;
    margin: 2rem 0 1rem;
    color: var(--text-primary);
}

.content-page h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 1.5rem 0 1rem;
    color: var(--text-primary);
}

.content-page p {
    margin-bottom: 1rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.content-page ul,
.content-page ol {
    margin-bottom: 1rem;
    padding-left: 2rem;
    color: var(--text-secondary);
}

.content-page li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

.contact-form {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    margin: 2rem 0;
}

.success-message {
    background: var(--bg-white);
    padding: 3rem 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-light);
    text-align: center;
    margin: 2rem 0;
}

.success-icon {
    width: 64px;
    height: 64px;
    background: var(--secondary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 2rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-white);
        flex-direction: column;
        padding: 1rem;
        box-shadow: var(--shadow-md);
        gap: 1rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }

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

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

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

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

    .course-header {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .checkout-container {
        grid-template-columns: 1fr;
    }

    .checkout-sidebar {
        position: static;
    }

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

    .form-row.three-col {
        grid-template-columns: 1fr;
    }

    .trust-features {
        gap: 1rem;
        justify-content: center;
    }

    .trust-item {
        flex-direction: column;
        text-align: center;
        gap: 0.5rem;
    }

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

    .tab-buttons {
        flex-wrap: wrap;
        gap: 0.5rem;
    }

    .tab-button {
        padding: 0.75rem 1rem;
        font-size: 0.875rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }

    .hero {
        padding: 2rem 0;
    }

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

    .hero-actions {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        max-width: 280px;
    }

    .checkout-steps {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }

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

    .course-card {
        margin: 0 0.5rem;
    }
}

/* 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 */
.btn:focus,
input:focus,
select:focus,
textarea:focus,
button:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

.nav-link:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 4px;
    border-radius: 4px;
}