* {
    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;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: #6366f1;
    font-weight: bold;
    font-size: 1.25rem;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
    margin: 0;
}

.nav-link {
    text-decoration: none;
    color: #333;
    font-weight: 500;
    transition: color 0.3s;
}

.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: 3px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    color: white;
    padding: 4rem 0;
    min-height: 60vh;
    display: flex;
    align-items: center;
}

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

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

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

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

.hero-image img {
    width: 100%;
    height: auto;
    border-radius: 10px;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    border: 2px solid transparent;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background: #f8fafc;
    transform: translateY(-2px);
}

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

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

.btn-outline {
    background: transparent;
    color: #6366f1;
    border-color: #6366f1;
}

.btn-outline:hover {
    background: #6366f1;
    color: #fff;
}

/* Features Section */
.features {
    padding: 4rem 0;
    background: #f8fafc;
}

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

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

.feature-card {
    background: #fff;
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

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

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #1e293b;
}

.feature-card p {
    color: #64748b;
    line-height: 1.6;
}

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

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

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

.course-card {
    background: #fff;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s, box-shadow 0.3s;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

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

.course-content {
    padding: 1.5rem;
}

.course-meta {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: #64748b;
}

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

.course-title a {
    text-decoration: none;
    color: inherit;
}

.course-title a:hover {
    color: #6366f1;
}

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

.course-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid #e2e8f0;
}

.course-price {
    font-size: 1.5rem;
    font-weight: bold;
    color: #6366f1;
}

.course-tag {
    display: inline-block;
    background: #6366f1;
    color: #fff;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 500;
    margin-bottom: 1rem;
}

/* Course Details Page */
.course-header {
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    color: white;
    padding: 3rem 0;
}

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

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

.course-info .course-meta {
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 1rem;
}

.course-sidebar {
    background: rgba(255, 255, 255, 0.1);
    padding: 2rem;
    border-radius: 12px;
    backdrop-filter: blur(10px);
}

.course-sidebar .course-price {
    color: #fff;
    font-size: 2rem;
    margin-bottom: 1rem;
}

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

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

.course-main {
    background: #fff;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.course-sidebar-content {
    background: #fff;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    height: fit-content;
    position: sticky;
    top: 100px;
}

.section-title {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #1e293b;
    border-bottom: 2px solid #6366f1;
    padding-bottom: 0.5rem;
}

.course-main ul,
.course-sidebar-content ul {
    list-style: none;
    padding-left: 0;
}

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

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

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

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

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid #d1d5db;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: #6366f1;
}

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

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

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

.form-checkbox input {
    margin-top: 0.25rem;
}

/* Checkout */
.checkout-header {
    background: #f8fafc;
    padding: 2rem 0;
    border-bottom: 1px solid #e2e8f0;
}

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

.checkout-step {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: 25px;
    background: #e2e8f0;
    color: #64748b;
}

.checkout-step.active {
    background: #6366f1;
    color: #fff;
}

.checkout-content {
    padding: 3rem 0;
}

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

.checkout-form {
    background: #fff;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.checkout-summary {
    background: #f8fafc;
    padding: 2rem;
    border-radius: 12px;
    height: fit-content;
}

.summary-item {
    display: flex;
    justify-content: space-between;
    padding: 0.75rem 0;
    border-bottom: 1px solid #e2e8f0;
}

.summary-total {
    font-weight: bold;
    font-size: 1.25rem;
    color: #1e293b;
}

.trust-icons {
    display: flex;
    gap: 1rem;
    margin: 1rem 0;
    justify-content: center;
}

.trust-icon {
    width: 40px;
    height: 25px;
    background: #f1f5f9;
    border: 1px solid #e2e8f0;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: bold;
    color: #64748b;
}

/* Courses Page */
.courses-header {
    background: #f8fafc;
    padding: 3rem 0;
    text-align: center;
}

.courses-filters {
    background: #fff;
    padding: 2rem 0;
    border-bottom: 1px solid #e2e8f0;
    margin-bottom: 2rem;
}

.filters-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 1rem;
    align-items: end;
}

.search-box {
    position: relative;
}

.search-input {
    width: 100%;
    padding: 0.75rem 1rem 0.75rem 2.5rem;
    border: 2px solid #d1d5db;
    border-radius: 8px;
    font-size: 1rem;
}

.search-icon {
    position: absolute;
    left: 0.75rem;
    top: 50%;
    transform: translateY(-50%);
    color: #64748b;
}

/* Footer */
.footer {
    background: #1e293b;
    color: #fff;
    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,
.footer-section h4 {
    margin-bottom: 1rem;
    color: #fff;
}

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

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

.footer-section a {
    color: #cbd5e1;
    text-decoration: none;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: #fff;
}

.footer-bottom {
    border-top: 1px solid #334155;
    padding-top: 1rem;
    text-align: center;
    color: #cbd5e1;
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .courses-grid {
        grid-template-columns: 1fr;
    }
    
    .course-header .container {
        grid-template-columns: 1fr;
    }
    
    .course-details .container {
        grid-template-columns: 1fr;
    }
    
    .checkout-grid {
        grid-template-columns: 1fr;
    }
    
    .filters-grid {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .checkout-steps {
        flex-direction: column;
        align-items: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .hero h1 {
        font-size: 1.75rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .features {
        padding: 2rem 0;
    }
    
    .featured-courses {
        padding: 2rem 0;
    }
    
    .course-details {
        padding: 2rem 0;
    }
    
    .checkout-content {
        padding: 2rem 0;
    }
}

/* Focus States for Accessibility */
button:focus,
.btn:focus,
.form-input:focus,
.form-select:focus,
.form-textarea:focus,
.nav-link:focus {
    outline: 2px solid #6366f1;
    outline-offset: 2px;
}

/* Error States */
.form-error {
    border-color: #ef4444;
}

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

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

/* Loading States */
.loading {
    opacity: 0.6;
    pointer-events: none;
}