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

:root {
    --primary-color: hsl(297, 70%, 50%);
    --primary-hover: hsl(297, 70%, 45%);
    --secondary-color: hsl(220, 15%, 25%);
    --accent-color: hsl(45, 100%, 60%);
    --text-primary: hsl(220, 15%, 20%);
    --text-secondary: hsl(220, 10%, 50%);
    --background: hsl(0, 0%, 100%);
    --background-alt: hsl(220, 20%, 98%);
    --border-color: hsl(220, 15%, 90%);
    --success-color: hsl(140, 60%, 50%);
    --error-color: hsl(0, 70%, 55%);
    --warning-color: hsl(30, 100%, 60%);
    --shadow: 0 2px 10px hsla(220, 15%, 20%, 0.1);
    --shadow-hover: 0 4px 20px hsla(220, 15%, 20%, 0.15);
    --border-radius: 8px;
    --max-width: 1200px;
    --header-height: 70px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--background);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.header {
    background: var(--background);
    border-bottom: 1px solid var(--border-color);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    height: var(--header-height);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: var(--text-primary);
}

.logo {
    width: 32px;
    height: 32px;
}

.brand-text {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-link {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    transition: color 0.3s ease;
    padding: 5px 0;
    position: relative;
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    margin: 2px 0;
    transition: 0.3s;
}

/* Main Content */
main {
    margin-top: var(--header-height);
}

/* Hero Section */
.hero {
    padding: 80px 0;
    background: linear-gradient(135deg, var(--background-alt) 0%, var(--background) 100%);
    position: relative;
    overflow: hidden;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 20px;
    color: var(--text-primary);
}

.hero-description {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 30px;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: 20px;
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
    border: 2px solid transparent;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

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

.btn-secondary:hover {
    background: hsl(220, 15%, 20%);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

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

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

.btn-full {
    width: 100%;
}

/* Trust Section */
.trust-section {
    padding: 60px 0;
    background: var(--background);
}

.trust-items {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
}

.trust-item {
    text-align: center;
    padding: 30px 20px;
    border-radius: var(--border-radius);
    background: var(--background-alt);
}

.trust-icon {
    font-size: 2.5rem;
    margin-bottom: 20px;
}

.trust-item h3 {
    font-size: 1.25rem;
    margin-bottom: 15px;
    color: var(--text-primary);
}

.trust-item p {
    color: var(--text-secondary);
}

/* Sections */
.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 20px;
    color: var(--text-primary);
}

.section-description {
    font-size: 1.25rem;
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 50px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.section-cta {
    text-align: center;
    margin-top: 50px;
}

/* Featured Courses */
.featured-courses {
    padding: 80px 0;
    background: var(--background-alt);
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
    margin-bottom: 50px;
}

.course-card {
    background: var(--background);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: all 0.3s ease;
    text-decoration: none;
    color: inherit;
}

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

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

.course-content {
    padding: 25px;
}

.course-tag {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 15px;
}

.course-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.course-description {
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.5;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

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

/* Features */
.features {
    padding: 80px 0;
    background: var(--background);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 40px;
}

.feature {
    text-align: center;
    padding: 40px 20px;
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 20px;
}

.feature h3 {
    font-size: 1.25rem;
    margin-bottom: 15px;
    color: var(--text-primary);
}

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

/* Course Catalog */
.catalog-header {
    padding: 40px 0;
    background: var(--background-alt);
}

.catalog-controls {
    display: flex;
    gap: 20px;
    margin-bottom: 40px;
    flex-wrap: wrap;
    align-items: center;
}

.search-box,
.filter-select {
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background: var(--background);
}

.search-box {
    flex: 1;
    min-width: 250px;
}

.filter-select {
    min-width: 150px;
}

/* Course Detail */
.course-detail {
    padding: 40px 0;
}

.course-detail-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 60px;
}

.course-detail-content h1 {
    font-size: 2.5rem;
    margin-bottom: 20px;
    color: var(--text-primary);
}

.course-detail-sidebar {
    position: sticky;
    top: calc(var(--header-height) + 20px);
    height: fit-content;
}

.course-purchase-card {
    background: var(--background-alt);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.course-purchase-price {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.course-info-list {
    list-style: none;
    margin: 20px 0;
}

.course-info-list li {
    padding: 8px 0;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
}

.course-info-list li:last-child {
    border-bottom: none;
}

.course-section {
    margin-bottom: 40px;
}

.course-section h2 {
    font-size: 1.75rem;
    margin-bottom: 20px;
    color: var(--text-primary);
}

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

.course-section li {
    padding: 8px 0;
    padding-left: 20px;
    position: relative;
}

.course-section li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: bold;
}

.curriculum-item {
    background: var(--background-alt);
    padding: 15px 20px;
    border-radius: var(--border-radius);
    margin-bottom: 10px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-item {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 10px;
}

.faq-question {
    background: none;
    border: none;
    padding: 20px;
    width: 100%;
    text-align: left;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-answer {
    padding: 0 20px 20px;
    display: none;
    color: var(--text-secondary);
}

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

/* Forms */
.form-group {
    margin-bottom: 20px;
}

.form-label {
    display: block;
    margin-bottom: 5px;
    font-weight: 600;
    color: var(--text-primary);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background: var(--background);
    transition: border-color 0.3s ease;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

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

.form-error {
    color: var(--error-color);
    font-size: 0.875rem;
    margin-top: 5px;
}

.form-checkbox {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    margin: 20px 0;
}

.form-checkbox input {
    margin-top: 3px;
}

/* Checkout */
.checkout-header {
    padding: 40px 0;
    background: var(--background-alt);
    text-align: center;
}

.checkout-steps {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin-bottom: 30px;
}

.checkout-step {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 20px;
    border-radius: var(--border-radius);
    background: var(--background);
    color: var(--text-secondary);
}

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

.checkout-content {
    padding: 40px 0;
}

.checkout-grid {
    display: grid;
    grid-template-columns: 1fr 400px;
    gap: 60px;
}

.checkout-summary {
    background: var(--background-alt);
    padding: 30px;
    border-radius: var(--border-radius);
    height: fit-content;
    position: sticky;
    top: calc(var(--header-height) + 20px);
}

.summary-item {
    display: flex;
    justify-content: space-between;
    padding: 10px 0;
    border-bottom: 1px solid var(--border-color);
}

.summary-item:last-child {
    border-bottom: none;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--primary-color);
}

.payment-icons {
    display: flex;
    gap: 10px;
    margin: 20px 0;
    justify-content: center;
}

.payment-icon {
    width: 40px;
    height: 25px;
    background: var(--border-color);
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: bold;
}

/* Success Page */
.success-content {
    padding: 80px 0;
    text-align: center;
}

.success-icon {
    font-size: 4rem;
    color: var(--success-color);
    margin-bottom: 30px;
}

.success-title {
    font-size: 2.5rem;
    margin-bottom: 20px;
    color: var(--text-primary);
}

.success-description {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 40px;
}

.order-details {
    background: var(--background-alt);
    padding: 30px;
    border-radius: var(--border-radius);
    margin: 40px auto;
    max-width: 500px;
    text-align: left;
}

/* Footer */
.footer {
    background: var(--secondary-color);
    color: white;
    padding: 60px 0 20px;
    margin-top: 80px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h4 {
    font-size: 1.25rem;
    margin-bottom: 20px;
    color: white;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 20px;
}

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

.footer-links li {
    margin-bottom: 10px;
}

.footer-links a {
    color: hsla(0, 0%, 100%, 0.8);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.footer-bottom {
    border-top: 1px solid hsla(0, 0%, 100%, 0.2);
    padding-top: 20px;
    text-align: center;
    color: hsla(0, 0%, 100%, 0.7);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--background);
        border-top: 1px solid var(--border-color);
        flex-direction: column;
        padding: 20px;
        gap: 10px;
    }

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

    .nav-toggle {
        display: flex;
    }

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

    .hero-title {
        font-size: 2.5rem;
    }

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

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

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

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

    .checkout-steps {
        flex-direction: column;
        align-items: center;
        gap: 10px;
    }

    .catalog-controls {
        flex-direction: column;
    }

    .search-box {
        min-width: auto;
    }

    .section-title {
        font-size: 2rem;
    }

    .trust-items {
        grid-template-columns: 1fr;
    }

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

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

    .hero {
        padding: 40px 0;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-description {
        font-size: 1rem;
    }

    .section-title {
        font-size: 1.75rem;
    }

    .course-card {
        margin: 0 10px;
    }

    .btn {
        padding: 10px 20px;
        font-size: 0.875rem;
    }
}

/* 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 */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

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