* {
    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;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: #2563eb;
    font-weight: 700;
    font-size: 1.5rem;
}

.logo img {
    width: 40px;
    height: 40px;
    margin-right: 10px;
}

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

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

.nav-list a:hover,
.nav-list a:focus {
    color: #2563eb;
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
    text-align: center;
    transition: all 0.3s;
    border: 2px solid transparent;
    cursor: pointer;
    font-size: 1rem;
}

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

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

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

.btn-secondary:hover,
.btn-secondary:focus {
    background: #2563eb;
    color: white;
}

.btn-full {
    width: 100%;
}

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

.hero-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

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

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

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.hero-image {
    text-align: center;
    margin-top: 2rem;
}

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

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

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

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

.feature-card {
    background: white;
    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 {
    margin-bottom: 1rem;
    color: #1e293b;
}

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

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

.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;
    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-category {
    display: inline-block;
    background: #e0e7ff;
    color: #3730a3;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.course-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: #1e293b;
}

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

.course-title a:hover {
    color: #2563eb;
}

.course-meta {
    display: flex;
    gap: 1rem;
    margin-bottom: 0.5rem;
    font-size: 0.875rem;
    color: #64748b;
}

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

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

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

/* Trust Section */
.trust-section {
    padding: 4rem 0;
    background: #f8fafc;
}

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

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

.trust-item {
    text-align: center;
    padding: 2rem;
}

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

.trust-item h3 {
    margin-bottom: 1rem;
    color: #1e293b;
}

/* 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: 6px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

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

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

.form-error {
    color: #dc2626;
    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: flex-start;
    gap: 0.5rem;
}

.checkbox-group input[type="checkbox"] {
    margin-top: 0.25rem;
}

/* Course Detail */
.course-hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 3rem 0;
}

.course-hero-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 2rem;
    align-items: center;
}

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

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

.course-detail-content {
    padding: 4rem 0;
}

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

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

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

.course-section ul {
    list-style-position: inside;
    color: #64748b;
}

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

.curriculum-item {
    background: #f8fafc;
    padding: 1rem;
    border-radius: 6px;
    margin-bottom: 0.5rem;
    border-left: 4px solid #2563eb;
}

.faq-item {
    background: #f8fafc;
    padding: 1.5rem;
    border-radius: 6px;
    margin-bottom: 1rem;
}

.faq-question {
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1e293b;
}

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

.step {
    display: flex;
    align-items: center;
    padding: 0.5rem 1rem;
    background: #f3f4f6;
    color: #6b7280;
    border-radius: 6px;
    margin: 0 0.5rem;
}

.step.active {
    background: #2563eb;
    color: white;
}

.step-number {
    background: rgba(255,255,255,0.2);
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-right: 0.5rem;
    font-size: 0.875rem;
    font-weight: 600;
}

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

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

.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: #1e293b;
}

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

.payment-icon {
    width: 40px;
    height: 25px;
    background: #f3f4f6;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 600;
    color: #6b7280;
}

.security-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: #059669;
    font-size: 0.875rem;
    margin: 1rem 0;
}

/* 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 h3,
.footer-section h4 {
    margin-bottom: 1rem;
    color: #f1f5f9;
}

.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: white;
}

.footer-bottom {
    border-top: 1px solid #334155;
    padding-top: 1rem;
    text-align: center;
    color: #94a3b8;
}

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

.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 1.5rem; }

.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 1rem; }
.mt-4 { margin-top: 1.5rem; }

/* Responsive Design */
@media (max-width: 768px) {
    .nav {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .course-hero-content,
    .course-detail-grid,
    .checkout-content {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .features-grid,
    .courses-grid {
        grid-template-columns: 1fr;
    }
    
    .checkout-steps {
        flex-direction: column;
        align-items: center;
    }
    
    .step {
        margin: 0.25rem 0;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .features,
    .featured-courses,
    .trust-section {
        padding: 2rem 0;
    }
    
    .course-detail-content {
        padding: 2rem 0;
    }
}

/* Focus States for Accessibility */
a:focus,
button:focus,
input:focus,
select:focus,
textarea:focus {
    outline: 2px solid #2563eb;
    outline-offset: 2px;
}

/* Loading State */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid #f3f4f6;
    border-top: 4px solid #2563eb;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}