:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --primary-light: #6366f1;
    --secondary-color: #64748b;
    --background: #fafbfc;
    --surface: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --border-color: #e2e8f0;
    --success-color: #10b981;
    --accent-color: #f59e0b;
    --accent-light: #fbbf24;
    --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.08);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.06);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.05);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 10px 10px -5px rgb(0 0 0 / 0.04);
    --radius: 10px;
    --radius-lg: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Inter', sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background);
    background-image: 
        radial-gradient(circle at 20% 50%, rgba(79, 70, 229, 0.03) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(245, 158, 11, 0.03) 0%, transparent 50%);
    background-attachment: fixed;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.header {
    background: rgba(255, 255, 255, 0.85);
    border-bottom: 1px solid var(--border-color);
    padding: 1.25rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(20px) saturate(180%);
    box-shadow: 0 1px 3px 0 rgb(0 0 0 / 0.05);
}

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

.logo {
    font-size: 1.75rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
}

.logo-link {
    text-decoration: none;
    color: inherit;
}

.nav {
    display: flex;
    gap: 2rem;
}

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

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

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

.donate-button {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: var(--background);
    border: 2px solid #ff6b9d;
    border-radius: 50%;
    text-decoration: none;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
    margin-left: 1rem;
}

.donate-button:hover {
    transform: translateY(-2px) scale(1.1);
    box-shadow: var(--shadow-md);
    background: #fff5f7;
    border-color: #ff8fab;
}

.heart-icon {
    width: 24px;
    height: 24px;
    transition: var(--transition);
}

.donate-button:hover .heart-icon {
    transform: scale(1.1);
    filter: drop-shadow(0 2px 4px rgba(255, 107, 157, 0.4));
}

/* Hero Section */
.hero {
    padding: 5rem 0;
    text-align: center;
    background: 
        linear-gradient(135deg, rgba(79, 70, 229, 0.95) 0%, rgba(99, 102, 241, 0.95) 50%, rgba(139, 92, 246, 0.9) 100%),
        radial-gradient(circle at 30% 20%, rgba(245, 158, 11, 0.2) 0%, transparent 50%),
        radial-gradient(circle at 70% 80%, rgba(236, 72, 153, 0.15) 0%, transparent 50%);
    color: white;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        repeating-linear-gradient(45deg, transparent, transparent 35px, rgba(255, 255, 255, 0.03) 35px, rgba(255, 255, 255, 0.03) 70px);
    pointer-events: none;
}

.hero .container {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    margin-bottom: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    line-height: 1.2;
}

.hero-description {
    font-size: 1.25rem;
    opacity: 0.95;
    max-width: 650px;
    margin: 0 auto;
    line-height: 1.7;
    font-weight: 400;
}

/* Courses Section */
.courses-section {
    padding: 5rem 0;
    position: relative;
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    text-align: center;
    color: var(--text-primary);
    font-weight: 800;
    letter-spacing: -0.02em;
    position: relative;
    display: inline-block;
    width: 100%;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -0.75rem;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--accent-color) 100%);
    border-radius: 2px;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    max-width: 900px;
    margin: 0 auto;
}

.course-card {
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.course-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--primary-light) 50%, var(--accent-color) 100%);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

.course-card:hover::before {
    transform: scaleX(1);
}

.course-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-6px);
    border-color: rgba(79, 70, 229, 0.2);
}

.course-card-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 1rem;
}

.course-title {
    font-size: 1.75rem;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
    font-weight: 700;
    letter-spacing: -0.01em;
}

.course-badges {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    align-items: center;
}

.course-badge {
    background: linear-gradient(135deg, var(--success-color) 0%, #059669 100%);
    color: white;
    padding: 0.35rem 0.85rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3);
}

.course-badge-beta {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    box-shadow: 0 2px 8px rgba(245, 158, 11, 0.3);
}

.course-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.course-meta {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.course-stats {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.course-button {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    padding: 0.875rem 1.75rem;
    border-radius: var(--radius);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    width: 100%;
    text-align: center;
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
    position: relative;
    overflow: hidden;
}

.course-button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s ease;
}

.course-button:hover::before {
    left: 100%;
}

.course-button:hover {
    background: linear-gradient(135deg, var(--primary-hover) 0%, var(--primary-color) 100%);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(79, 70, 229, 0.4);
}

/* Course Page */
.course-main {
    padding: 2rem 0;
    min-height: calc(100vh - 200px);
}

.course-container {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 2rem;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Sidebar */
.course-sidebar {
    position: sticky;
    top: 80px;
    height: fit-content;
    max-height: calc(100vh - 100px);
    overflow-y: auto;
}

.course-progress {
    background: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

.course-progress h3 {
    font-size: 1rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--primary-light) 100%);
    transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    width: 0%;
    border-radius: 4px;
    box-shadow: 0 0 10px rgba(79, 70, 229, 0.4);
}

.progress-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 600;
}

.course-nav {
    background: var(--surface);
    padding: 1.75rem;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.course-nav h3 {
    font-size: 1rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.course-sections {
    list-style: none;
}

.course-section {
    margin-bottom: 1rem;
}

.section-header {
    font-weight: 600;
    color: var(--text-primary);
    padding: 0.5rem 0;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
}

.section-header:hover {
    color: var(--primary-color);
}

.section-header.active {
    color: var(--primary-color);
}

.section-lessons {
    list-style: none;
    margin-top: 0.5rem;
    padding-left: 1rem;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.section-lessons.expanded {
    max-height: 1000px;
}

.lesson-item {
    padding: 0.5rem 0;
}

.lesson-link {
    text-decoration: none;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem;
    border-radius: var(--radius);
    transition: var(--transition);
    font-size: 0.9rem;
}

.lesson-link:hover {
    background: var(--background);
    color: var(--primary-color);
}

.lesson-link.active {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    box-shadow: 0 2px 8px rgba(79, 70, 229, 0.3);
}

.lesson-link.completed::before {
    content: '✓';
    color: var(--success-color);
    font-weight: bold;
}

.lesson-link.completed.active::before {
    color: white;
}

/* Course Content */
.course-content {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    border: 1px solid var(--border-color);
    min-height: 600px;
    box-shadow: var(--shadow-sm);
}

.lesson-placeholder {
    text-align: left;
    padding: 2.5rem;
    color: var(--text-secondary);
    max-width: 100%;
}

.lesson-placeholder h1 {
    font-size: 2.25rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    padding-bottom: 1.25rem;
    border-bottom: 3px solid;
    border-image: linear-gradient(90deg, var(--primary-color) 0%, var(--accent-color) 100%) 1;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.lesson-placeholder h2 {
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-size: 1.5rem;
    font-weight: 700;
}

.lesson-placeholder p {
    text-align: left;
    margin: 1rem 0;
    color: var(--text-primary);
}

.lesson-placeholder ul {
    text-align: left;
    margin: 1rem 0;
    padding-left: 1.5rem;
}

.lesson-placeholder li {
    text-align: left;
    margin: 0.5rem 0;
    line-height: 1.8;
}

.lesson-placeholder .intro-text {
    font-size: 1.25rem;
    line-height: 1.8;
    margin: 2rem 0;
    color: var(--text-primary);
}

.lesson-placeholder .skills-list {
    list-style: none;
    padding-left: 0;
    margin: 1.5rem 0;
}

.lesson-placeholder .skills-list li {
    padding-left: 1.75rem;
    position: relative;
    margin: 0.75rem 0;
    line-height: 1.8;
}

.lesson-placeholder .skills-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: bold;
    font-size: 1.1rem;
}

.lesson-placeholder .course-sections-box {
    background: var(--background);
    padding: 1.5rem;
    border-radius: var(--radius);
    margin: 1.5rem 0;
    border-left: 4px solid var(--primary-color);
}

.lesson-placeholder .sections-list {
    margin: 0;
    padding-left: 1.5rem;
    list-style-position: outside;
}

.lesson-placeholder .sections-list li {
    margin: 0.75rem 0;
    line-height: 1.8;
}

.lesson-placeholder .call-to-action {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--primary-color);
    margin: 2rem 0;
}

.lesson-placeholder .tip-box {
    margin-top: 2rem;
    padding: 1.5rem;
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1) 0%, rgba(99, 102, 241, 0.1) 100%);
    border-radius: var(--radius);
    border-left: 4px solid var(--primary-color);
    line-height: 1.8;
}

.start-course-actions {
    margin-top: 2rem;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
}

.start-course-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.9rem 1.8rem;
    border-radius: var(--radius-lg);
    border: none;
    cursor: pointer;
    font-weight: 600;
    font-size: 1rem;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: #ffffff;
    box-shadow: 0 4px 14px rgba(79, 70, 229, 0.35);
    transition: var(--transition);
}

.start-course-button:hover {
    background: linear-gradient(135deg, var(--primary-hover) 0%, var(--primary-color) 100%);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(79, 70, 229, 0.45);
}

.start-course-button:active {
    transform: translateY(0);
    box-shadow: 0 3px 10px rgba(79, 70, 229, 0.3);
}

.start-course-button:focus-visible {
    outline: 2px solid rgba(79, 70, 229, 0.7);
    outline-offset: 3px;
}

.start-course-hint {
    font-size: 0.9rem;
    color: var(--text-secondary);
    max-width: 420px;
}

.lesson-content {
    line-height: 1.8;
}

.lesson-content h1 {
    font-size: 2.25rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    padding-bottom: 1.25rem;
    border-bottom: 3px solid;
    border-image: linear-gradient(90deg, var(--primary-color) 0%, var(--accent-color) 100%) 1;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.lesson-content h2 {
    font-size: 1.5rem;
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.lesson-content h3 {
    font-size: 1.375rem;
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-weight: 600;
}

.lesson-content p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.lesson-content ul,
.lesson-content ol {
    margin-bottom: 1.5rem;
    padding-left: 2rem;
    color: var(--text-secondary);
}

.lesson-content ul li::marker {
    color: var(--primary-color);
    font-weight: bold;
}

.lesson-content li {
    margin-bottom: 0.5rem;
}

.lesson-content code {
    background: var(--surface);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    font-size: 0.9em;
    color: var(--primary-color);
}

.lesson-content pre {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.03) 0%, rgba(245, 158, 11, 0.03) 100%);
    padding: 1.75rem;
    border-radius: var(--radius);
    overflow-x: auto;
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.02);
    position: relative;
}

.lesson-content pre::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--primary-color) 0%, var(--accent-color) 100%);
    border-radius: var(--radius) 0 0 var(--radius);
}

.lesson-content pre code {
    background: none;
    padding: 0;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.lesson-content a {
    color: var(--primary-color);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: var(--transition);
}

.lesson-content a:hover {
    color: var(--primary-hover);
    border-bottom-color: var(--primary-hover);
}

.lesson-content a:visited {
    color: var(--primary-color);
}

.lesson-content blockquote {
    border-left: 4px solid var(--primary-color);
    padding-left: 1rem;
    padding-right: 6rem;
    margin: 1.5rem 0;
    color: var(--text-secondary);
    font-style: italic;
    position: relative;
}

.lesson-content .copy-blockquote-button {
    position: absolute;
    top: 0.25rem;
    right: 0.25rem;
    background: rgba(79, 70, 229, 0.10);
    border: 1px solid rgba(79, 70, 229, 0.20);
    color: var(--primary-color);
    border-radius: 999px;
    padding: 0.25rem 0.45rem;
    font-size: 0.75rem;
    font-weight: 700;
    line-height: 1;
    cursor: pointer;
    font-style: normal;
    transition: var(--transition);
}

.lesson-content .copy-blockquote-button:hover {
    background: rgba(79, 70, 229, 0.16);
    border-color: rgba(79, 70, 229, 0.30);
    transform: translateY(-1px);
}

.lesson-content .copy-blockquote-button:disabled {
    opacity: 0.7;
    cursor: default;
    transform: none;
}

.lesson-content .copy-blockquote-button:active {
    transform: translateY(0);
}

.lesson-content .copy-blockquote-button:focus-visible {
    outline: 2px solid rgba(79, 70, 229, 0.35);
    outline-offset: 2px;
}

.lesson-content .copy-blockquote-button.copied {
    background: rgba(16, 185, 129, 0.12);
    border-color: rgba(16, 185, 129, 0.30);
    color: var(--success-color);
}

.lesson-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius);
    margin: 1.5rem 0;
}

.lesson-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 2rem 0;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.lesson-content th,
.lesson-content td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.lesson-content th {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1) 0%, rgba(99, 102, 241, 0.1) 100%);
    font-weight: 700;
    color: var(--text-primary);
    text-transform: uppercase;
    font-size: 0.875rem;
    letter-spacing: 0.5px;
}

/* Lesson Navigation */
.lesson-navigation {
    display: flex;
    justify-content: space-between;
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.nav-button {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    border: none;
    padding: 0.875rem 1.75rem;
    border-radius: var(--radius);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.25);
}

.nav-button:hover:not(:disabled) {
    background: linear-gradient(135deg, var(--primary-hover) 0%, var(--primary-color) 100%);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(79, 70, 229, 0.35);
}

.nav-button:disabled {
    background: var(--border-color);
    color: var(--text-secondary);
    cursor: not-allowed;
    opacity: 0.5;
}

/* Footer */
.footer {
    background: linear-gradient(180deg, var(--surface) 0%, var(--background) 100%);
    padding: 3rem 0;
    text-align: center;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
    margin-top: 5rem;
    position: relative;
}

.footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent 0%, var(--primary-color) 50%, transparent 100%);
}

/* Responsive */
@media (max-width: 968px) {
    .course-container {
        grid-template-columns: 1fr;
    }

    .course-sidebar {
        position: relative;
        top: 0;
        max-height: none;
    }

    .header-content {
        flex-direction: column;
        gap: 1rem;
    }

    .nav {
        gap: 1rem;
    }

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

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

/* Final Test Styles */
.final-test {
    margin-top: 3rem;
    padding: 2rem;
    background: var(--surface);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.test-header {
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
}

.test-header h3 {
    font-size: 1.75rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    font-weight: 700;
}

.test-progress {
    color: var(--text-secondary);
    font-weight: 600;
}

.test-question {
    margin-bottom: 2.5rem;
    padding: 1.5rem;
    background: var(--background);
    border-radius: var(--radius);
    border-left: 4px solid var(--primary-color);
}

.test-question h4 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    font-weight: 600;
    line-height: 1.5;
}

.test-options {
    list-style: none;
    padding: 0;
    margin: 0;
}

.test-option {
    margin-bottom: 1rem;
    padding: 1rem;
    background: var(--surface);
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
}

.test-option:hover {
    border-color: var(--primary-color);
    background: rgba(79, 70, 229, 0.05);
    transform: translateX(4px);
}

.test-option input[type="radio"] {
    margin: 0;
    margin-top: 0.125rem;
    cursor: pointer;
    width: 18px;
    height: 18px;
    accent-color: var(--primary-color);
    flex-shrink: 0;
}

.test-option label {
    cursor: pointer;
    display: block;
    flex: 1;
    color: var(--text-primary);
    font-weight: 500;
    line-height: 1.5;
    margin: 0;
}

.test-option.correct {
    background: rgba(16, 185, 129, 0.1);
    border-color: var(--success-color);
}

.test-option.incorrect {
    background: rgba(239, 68, 68, 0.1);
    border-color: #ef4444;
}

.test-option.disabled {
    cursor: not-allowed;
    opacity: 0.7;
}

.test-option.disabled:hover {
    transform: none;
    border-color: var(--border-color);
}

.test-navigation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.test-question-counter {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.test-button {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    border: none;
    padding: 0.875rem 1.75rem;
    border-radius: var(--radius);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.25);
}

.test-button:hover:not(:disabled) {
    background: linear-gradient(135deg, var(--primary-hover) 0%, var(--primary-color) 100%);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(79, 70, 229, 0.35);
}

.test-button:disabled {
    background: var(--border-color);
    color: var(--text-secondary);
    cursor: not-allowed;
    opacity: 0.5;
    transform: none;
    box-shadow: none;
}

.test-results {
    text-align: center;
    padding: 2rem;
}

.test-score {
    margin-bottom: 2rem;
}

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

.score-percentage {
    font-size: 3rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin: 1rem 0;
}

.test-feedback {
    margin: 2rem 0;
    padding: 1.5rem;
    background: var(--background);
    border-radius: var(--radius);
    border-left: 4px solid var(--primary-color);
}

.test-feedback h4 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.test-feedback ul {
    text-align: left;
    max-width: 600px;
    margin: 0 auto;
    list-style: none;
    padding: 0;
}

.test-feedback li {
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    background: var(--surface);
    border-radius: var(--radius);
    color: var(--text-secondary);
}

@media (max-width: 640px) {
    .courses-grid {
        grid-template-columns: 1fr;
    }

    .course-content {
        padding: 1.5rem;
    }

    .lesson-navigation {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-button {
        width: 100%;
    }

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

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

    .section-title::after {
        width: 40px;
    }

    .final-test {
        padding: 1.5rem;
    }

    .test-navigation {
        flex-direction: column;
        gap: 1rem;
    }

    .test-button {
        width: 100%;
    }
}