/* ============================================
   LESSON SYSTEM STYLES - ENHANCED VERSION
   ============================================ */

/* Global fix for overflow - allow horizontal scroll */
.lesson-card, .module, .module h2, section, .lesson-card a {
    max-width: 100%;
    box-sizing: border-box;
    overflow-x: auto;
}

.lesson-card a {
    width: 100%;
}

/* Custom scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: linear-gradient(90deg, var(--accent), var(--secondary));
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(90deg, #20c997, var(--accent));
}

/* Smooth page transitions */
.lesson {
    animation: fadeInUp 0.6s ease-out;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Lesson Navigation */
.lesson-nav {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    background: linear-gradient(135deg, rgba(0, 212, 170, 0.08), rgba(102, 126, 234, 0.05));
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-lg);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2), inset 0 1px 0 rgba(255, 255, 255, 0.05);
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
}

.lesson-nav a {
    color: var(--accent);
    text-decoration: none;
    font-family: 'Share Tech', sans-serif;
}

.lesson-nav a:hover {
    color: var(--text);
}

.lesson-progress-bar {
    flex: 1;
    max-width: 300px;
    height: 8px;
    background: var(--border);
    border-radius: 4px;
    margin: 0 1rem;
    overflow: hidden;
}

.lesson-progress-bar .progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent), var(--key-back));
    background-size: 200% 100%;
    transition: width 0.3s ease;
    width: 0%;
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { background-position: -200% 0; }
    100% { background-position: 200% 0; }
}

/* Lesson Header */
.lesson-header {
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg) 0;
    text-align: center;
}

.lesson-header h1 {
    font-size: clamp(2rem, 5vw, 2.5rem);
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, var(--accent), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.lesson-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    justify-content: center;
    color: var(--text-secondary);
    font-size: clamp(0.85rem, 2vw, 0.95rem);
}

.lesson-meta span {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-full);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

/* Lesson Content Sections */
.lesson-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
    max-width: 1000px;
    margin: 0 auto;
    width: 100%;
}

.lesson-content section {
    padding: var(--spacing-xl);
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.05), rgba(255, 255, 255, 0.02));
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2), inset 0 1px 0 rgba(255, 255, 255, 0.05);
    transition: all var(--transition-base);
}

.lesson-content section:hover {
    border-color: rgba(0, 212, 170, 0.2);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3), inset 0 1px 0 rgba(255, 255, 255, 0.1);
}

.lesson-content section h2 {
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--accent);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: clamp(1.3rem, 3vw, 1.6rem);
}

/* Theory Section */
.theory {
    line-height: 1.8;
    color: var(--text-secondary);
}

.theory p {
    margin-bottom: var(--spacing-md);
    font-size: clamp(0.95rem, 2vw, 1rem);
}

.theory ul, .theory ol {
    margin-left: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-sm);
}

.theory li {
    margin-bottom: var(--spacing-xs);
    line-height: 1.7;
}

.theory code {
    background: rgba(0, 212, 170, 0.15);
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    color: var(--accent);
    font-size: 0.9em;
    border: 1px solid rgba(0, 212, 170, 0.2);
}

.theory pre {
    background: var(--border-dark);
    padding: 1rem;
    border-radius: 0.3rem;
    overflow-x: auto;
    margin: 1rem 0;
}

.theory pre code {
    background: none;
    padding: 0;
    color: var(--text);
}

/* Shared content helpers: timelines, glossary, example boxes, etc. */
.timeline {
    margin: 1.5rem 0;
    padding-left: 2rem;
    border-left: 3px solid var(--accent);
    position: relative;
}

.timeline::before {
    content: '';
    position: absolute;
    left: -6px;
    top: 0;
    bottom: 0;
    width: 9px;
    background: radial-gradient(circle at center, var(--accent) 0, transparent 70%);
    opacity: 0.3;
}

.timeline-item {
    margin-bottom: 1rem;
    padding: 0.75rem 1rem;
    background: rgba(255, 255, 255, 0.04);
    border-radius: 0.5rem;
    border: 1px solid rgba(255, 255, 255, 0.08);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

.glossary {
    margin: 1.5rem 0;
}

.glossary dt {
    margin-top: 1rem;
    color: var(--accent);
    font-weight: 600;
}

.glossary dd {
    margin-left: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.example-box {
    background: rgba(255, 255, 255, 0.04);
    padding: 1rem 1.25rem;
    border-radius: 0.75rem;
    margin: 1rem 0;
    border-left: 4px solid var(--accent);
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    border-right: 1px solid rgba(255, 255, 255, 0.04);
    border-bottom: 1px solid rgba(0, 0, 0, 0.4);
}

.security-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    background: rgba(0, 0, 0, 0.25);
    border-radius: 0.75rem;
    overflow: hidden;
}

.security-table th,
.security-table td {
    padding: 0.85rem 1rem;
    border: 1px solid rgba(255, 255, 255, 0.08);
    text-align: left;
    font-size: 0.95rem;
}

.security-table th {
    background: linear-gradient(135deg, var(--accent), var(--secondary));
    color: var(--text-inv);
    font-weight: 600;
}

.security-table tr:nth-child(even) {
    background: rgba(255, 255, 255, 0.04);
}

.demo-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 0.5rem;
}

.demo-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.demo-input,
.interactive-demo input[type="text"],
.interactive-demo select {
    padding: 0.8rem 1rem;
    font-family: 'Share Tech Mono', monospace;
    font-size: 1rem;
    border-radius: 0.5rem;
    border: 1px solid rgba(255, 255, 255, 0.25);
    background: rgba(255, 255, 255, 0.06);
    color: var(--text-primary);
}

.interactive-demo .demo-result {
    padding: 1rem 1.25rem;
    background: rgba(255, 255, 255, 0.04);
    border-radius: 0.75rem;
    border: 1px solid rgba(255, 255, 255, 0.08);
}

/* Interactive Demo Section */
.interactive-demo {
    background: var(--back-high);
}

/* Quiz Section */
.quiz-questions {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.quiz-question {
    padding: 1rem;
    background: var(--border-dark);
    border-radius: 0.3rem;
    border-left: 4px solid var(--accent);
}

.quiz-question h4 {
    margin-bottom: 1rem;
    color: var(--accent);
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem;
    cursor: pointer;
    border-radius: 0.2rem;
    transition: background 0.2s;
}

.quiz-option:hover {
    background: var(--back-high);
}

.quiz-option input[type="radio"] {
    cursor: pointer;
}

.quiz-feedback {
    margin-top: 0.5rem;
    padding: 0.5rem;
    border-radius: 0.2rem;
    font-weight: bold;
}

.quiz-feedback.correct {
    background: rgba(76, 175, 80, 0.2);
    color: #4CAF50;
}

.quiz-feedback.incorrect {
    background: rgba(244, 67, 54, 0.2);
    color: #F44336;
}

.quiz-submit, .demo-btn {
    background: linear-gradient(135deg, var(--accent), var(--key-back));
    border: 1px solid rgba(255, 255, 255, 0.55);
    border-radius: 2rem;
    padding: 1rem 2rem;
    color: white;
    font-weight: bold;
    cursor: pointer;
    font-family: 'Share Tech', sans-serif;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    margin-top: 1rem;
    font-size: 1rem;
    box-shadow: 0 0 0 2px rgba(0, 0, 0, 0.15), 0 6px 18px rgba(41, 182, 246, 0.18);
}

.quiz-submit::before, .demo-btn::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;
}

.quiz-submit:hover::before, .demo-btn:hover::before {
    left: 100%;
}

.quiz-submit:hover, .demo-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(41, 182, 246, 0.4);
}

/* Light theme: keep a visible (but softer) outline */
body.light-theme .quiz-submit,
body.light-theme .demo-btn {
    border-color: rgba(0, 0, 0, 0.18);
    box-shadow: 0 0 0 2px rgba(255, 255, 255, 0.6), 0 10px 25px rgba(0, 0, 0, 0.08);
}

.quiz-submit:active, .demo-btn:active {
    transform: translateY(0);
}

/* Quiz & Challenge Responsive */
@media (max-width: 768px) {
    .quiz-question {
        padding: var(--spacing-md);
    }
    
    .quiz-question h4 {
        font-size: 1rem;
    }
    
    .quiz-option {
        padding: var(--spacing-sm);
        min-height: 44px;
        font-size: 0.9rem;
    }
    
    .quiz-submit,
    .demo-btn {
        width: 100%;
        padding: var(--spacing-md);
        font-size: 0.95rem;
        min-height: 44px;
    }
    
    .challenge-item {
        padding: var(--spacing-md);
    }
    
    .challenge-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-xs);
    }
    
    .challenge-input {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .challenge-input input {
        width: 100%;
        font-size: 16px; /* Prevents zoom on iOS */
        min-height: 44px;
    }
    
    .challenge-submit {
        width: 100%;
        min-height: 44px;
    }
}

@media (max-width: 480px) {
    .quiz-questions,
    .challenges-list {
        gap: var(--spacing-md);
    }
    
    .quiz-feedback {
        font-size: 0.85rem;
        padding: var(--spacing-xs);
    }
    
    .quiz-score {
        font-size: 1rem;
        padding: var(--spacing-md);
    }
}

.quiz-score {
    margin-top: 1rem;
    padding: 1rem;
    background: var(--accent);
    color: var(--text-inv);
    border-radius: 0.3rem;
    text-align: center;
    font-size: 1.2rem;
    font-weight: bold;
    display: none;
}

/* Challenge Section */
.challenges-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.challenge-item {
    padding: 1.5rem;
    background: var(--border-dark);
    border-radius: 0.3rem;
    border-left: 4px solid var(--key-back);
}

.challenge-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.challenge-header h4 {
    color: var(--key-back);
    margin: 0;
}

.challenge-badge {
    background: var(--key-back);
    color: var(--text-inv);
    padding: 0.3rem 0.8rem;
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: bold;
}

.challenge-description {
    margin-bottom: 1rem;
    line-height: 1.6;
}

.challenge-input {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}

.challenge-input input {
    flex: 1;
    padding: 0.5rem;
    border: 2px solid var(--border);
    border-radius: 0.3rem;
    background: var(--back);
    color: var(--text);
    font-family: 'Share Tech Mono', monospace;
}

.challenge-submit {
    padding: 0.5rem 1.5rem;
    background: var(--key-back);
    color: var(--text-inv);
    border: none;
    border-radius: 0.3rem;
    cursor: pointer;
    font-family: 'Share Tech', sans-serif;
    transition: background 0.2s;
}

.challenge-submit:hover {
    background: var(--stream-back);
}

.challenge-feedback {
    padding: 0.5rem;
    border-radius: 0.2rem;
    font-weight: bold;
    min-height: 1.5rem;
}

.challenge-feedback.correct {
    background: rgba(76, 175, 80, 0.2);
    color: #4CAF50;
}

.challenge-feedback.incorrect {
    background: rgba(244, 67, 54, 0.2);
    color: #F44336;
}

/* Loading, Empty, and Error States */
.loading-state,
.empty-state,
.error-state {
    padding: var(--spacing-xl);
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.1);
    margin: var(--spacing-md) 0;
}

.loading-state {
    animation: pulse 2s infinite;
}

.empty-state {
    color: var(--text-tertiary);
}

.error-state {
    color: var(--error);
    background: rgba(255, 107, 107, 0.1);
    border-color: rgba(255, 107, 107, 0.2);
}

/* Search Styles */
.search-container {
    position: relative;
    max-width: 300px;
    width: 100%;
    margin: 0;
    flex: 0 0 auto;
    min-width: 200px;
}

/* Search Responsive Enhancements */
@media (max-width: 768px) {
    .search-container {
        position: relative;
        width: 100%;
        margin-top: var(--spacing-md);
        padding: 0 var(--spacing-sm);
    }
    
    .search-input {
        width: 100%;
        font-size: 16px; /* Prevents zoom on iOS */
    }
}

@media (min-width: 769px) {
    .search-results {
        border-radius: var(--radius-md);
    }
}

.search-input {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1rem;
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: var(--radius-full);
    color: var(--text-primary);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
}

/* Search icon */
.search-container {
    position: relative;
}

.search-container::before {
    content: '🔍';
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1rem;
    opacity: 0.6;
    pointer-events: none;
    z-index: 1;
}

.search-input {
    padding-left: 2.75rem;
}

.search-input:focus {
    outline: none;
    border-color: var(--accent);
    background: rgba(255, 255, 255, 0.12);
    box-shadow: 
        0 0 0 3px rgba(0, 212, 170, 0.15),
        0 4px 20px rgba(0, 212, 170, 0.1);
    transform: scale(1.01);
}

.search-input::placeholder {
    color: rgba(255, 255, 255, 0.4);
}

/* Focus glow animation */
@keyframes searchGlow {
    0%, 100% { box-shadow: 0 0 0 3px rgba(0, 212, 170, 0.15), 0 4px 20px rgba(0, 212, 170, 0.1); }
    50% { box-shadow: 0 0 0 5px rgba(0, 212, 170, 0.2), 0 4px 25px rgba(0, 212, 170, 0.15); }
}

.search-input:focus {
    animation: searchGlow 2s ease-in-out infinite;
}

.search-results {
    display: none;
    position: absolute;
    top: calc(100% + 0.75rem);
    left: 0;
    right: 0;
    max-height: 450px;
    overflow-y: auto;
    background: linear-gradient(135deg, rgba(10, 14, 39, 0.98), rgba(20, 27, 45, 0.98));
    backdrop-filter: blur(20px);
    border: 1px solid rgba(0, 212, 170, 0.2);
    border-radius: var(--radius-lg);
    box-shadow: 
        0 10px 40px rgba(0, 0, 0, 0.4),
        0 0 20px rgba(0, 212, 170, 0.1);
    z-index: 1000;
    animation: slideDown 0.2s ease-out;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.search-result-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    text-decoration: none;
    color: var(--text-primary);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    transition: all 0.2s ease;
    position: relative;
}

.search-result-item::before {
    content: '📖';
    font-size: 1.2rem;
}

.search-result-item:hover {
    background: linear-gradient(90deg, rgba(0, 212, 170, 0.15), rgba(0, 212, 170, 0.05));
    padding-left: calc(var(--spacing-lg) + 0.5rem);
    border-left: 3px solid var(--accent);
}

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

.search-result-title {
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    font-size: 1.1rem;
}

.search-result-title mark {
    background: rgba(0, 212, 170, 0.3);
    color: var(--accent);
    padding: 0 0.2rem;
    border-radius: 0.2rem;
}

.search-result-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-xs);
}

.search-result-meta {
    display: flex;
    gap: var(--spacing-md);
    font-size: 0.85rem;
    color: var(--text-tertiary);
}

.search-result-item.no-results {
    text-align: center;
    color: var(--text-tertiary);
    padding: var(--spacing-xl);
}

/* Progress Actions */
.progress-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
    flex-wrap: wrap;
    justify-content: center;
}

/* Progress Actions Responsive */
@media (max-width: 480px) {
    .progress-actions {
        display: flex;
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .btn-progress {
        width: 100%;
        justify-content: center;
    }
}

@media (min-width: 481px) and (max-width: 768px) {
    .progress-actions {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 769px) {
    .progress-actions {
        display: flex;
        flex-direction: row;
        justify-content: center;
    }
}

.btn-progress {
    padding: var(--spacing-xs) var(--spacing-md);
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-base);
}

.btn-progress:hover {
    background: rgba(0, 212, 170, 0.2);
    border-color: var(--accent);
}

.btn-progress.btn-danger:hover {
    background: rgba(255, 107, 107, 0.2);
    border-color: var(--error);
}

/* Certificate Modal */
.certificate-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10000;
    animation: fadeIn 0.3s ease;
}

.certificate-content {
    background: linear-gradient(135deg, rgba(10, 14, 39, 0.98), rgba(20, 27, 45, 0.98));
    border: 2px solid var(--accent);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    max-width: 600px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
}

.certificate-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    border-bottom: 2px solid var(--accent);
    padding-bottom: var(--spacing-md);
}

.certificate-close {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 2rem;
    cursor: pointer;
    line-height: 1;
    padding: 0;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all var(--transition-base);
}

.certificate-close:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: rotate(90deg);
}

.certificate-body {
    text-align: center;
    padding: var(--spacing-xl);
}

.certificate-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: var(--spacing-sm);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.certificate-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

.certificate-course {
    font-size: 1.2rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-md);
    background: rgba(0, 212, 170, 0.1);
    border-radius: var(--radius-md);
}

.certificate-name {
    font-size: 1rem;
    color: var(--text-tertiary);
    margin-bottom: var(--spacing-xs);
}

.certificate-recipient {
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--accent);
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-md);
    border: 2px dashed var(--accent);
    border-radius: var(--radius-md);
}

.certificate-date {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

.certificate-stats {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.certificate-stats p {
    margin: var(--spacing-xs) 0;
    color: var(--text-secondary);
}

.certificate-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    margin-top: var(--spacing-lg);
}

.btn-certificate {
    padding: var(--spacing-md) var(--spacing-xl);
    background: linear-gradient(135deg, var(--accent), var(--secondary));
    color: white;
    border: none;
    border-radius: var(--radius-full);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.btn-certificate:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 212, 170, 0.4);
}

/* Certificate Responsive */
@media (max-width: 768px) {
    .certificate-modal {
        padding: var(--spacing-sm);
    }
    
    .certificate-content {
        border-radius: var(--radius-md);
    }
    
    .certificate-header h2 {
        font-size: 1.3rem;
    }
}

@media (orientation: landscape) and (max-height: 600px) {
    .certificate-body {
        padding: var(--spacing-md);
    }
    
    .certificate-title {
        font-size: 2rem;
    }
}

/* Lesson Footer */
.lesson-footer {
    display: flex;
    justify-content: space-between;
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 2px solid rgba(255, 255, 255, 0.1);
    gap: var(--spacing-md);
}

.btn-prev, .btn-next {
    background: linear-gradient(135deg, var(--accent), var(--key-back));
    border: none;
    border-radius: 2rem;
    padding: 1rem 2rem;
    color: white;
    font-weight: bold;
    cursor: pointer;
    font-family: 'Share Tech', sans-serif;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    text-decoration: none;
    display: inline-block;
    font-size: 1rem;
}

.btn-prev::before, .btn-next::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;
}

.btn-prev:hover::before, .btn-next:hover::before {
    left: 100%;
}

.btn-prev:hover, .btn-next:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(41, 182, 246, 0.4);
}

.btn-prev:active, .btn-next:active {
    transform: translateY(0);
}

.btn-prev:disabled, .btn-next:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

/* Completion Message */
.completion-message {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--back);
    border: 4px solid var(--accent);
    border-radius: 0.5rem;
    padding: 2rem;
    z-index: 1000;
    box-shadow: 0 4px 20px rgba(0,0,0,0.5);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translate(-50%, -60%);
    }
    to {
        opacity: 1;
        transform: translate(-50%, -50%);
    }
}

.completion-content {
    text-align: center;
}

.completion-content h3 {
    color: var(--accent);
    margin-bottom: 1rem;
}

.completion-content button {
    margin-top: 1rem;
    padding: 0.5rem 1.5rem;
    background: var(--accent);
    color: var(--text-inv);
    border: none;
    border-radius: 0.3rem;
    cursor: pointer;
}

/* Main Navigation Container */
#mainnav {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 3rem;
    padding: 0;
}

.lesson-card {
    width: 100%;
    max-width: none;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.06), rgba(255, 255, 255, 0.03));
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2), inset 0 1px 0 rgba(255, 255, 255, 0.05);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

/* Enhanced left border indicator */
.lesson-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--accent), var(--secondary));
    opacity: 0.4;
    transition: all 0.3s ease;
}

/* Shimmer effect */
.lesson-card::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.08), transparent);
    transition: left 0.6s ease;
}

.lesson-card:hover::before {
    opacity: 1;
    width: 5px;
}

.lesson-card:hover::after {
    left: 100%;
}

.lesson-card:hover {
    transform: translateY(-5px) scale(1.01);
    box-shadow: 
        0 20px 50px rgba(0, 212, 170, 0.25), 
        0 8px 20px rgba(0, 0, 0, 0.3),
        inset 0 1px 0 rgba(255, 255, 255, 0.15);
    border-color: rgba(0, 212, 170, 0.35);
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.04));
}

/* Completed state */
.lesson-card[data-completed="true"]::before {
    background: linear-gradient(180deg, var(--success), #20c997);
    opacity: 0.8;
}

/* Glow effect on hover for enhanced cards */
.lesson-card.enhanced-hover:hover {
    box-shadow: 
        0 0 30px rgba(0, 212, 170, 0.3),
        0 20px 50px rgba(0, 212, 170, 0.2),
        inset 0 1px 0 rgba(255, 255, 255, 0.15);
}

/* Color shift variant */
.lesson-card.color-shift {
    position: relative;
}

.lesson-card.color-shift::before {
    background: linear-gradient(180deg, #667eea, #764ba2);
}

/* Neon glow variant */
.lesson-card.neon-glow:hover {
    box-shadow: 
        0 0 25px rgba(102, 126, 234, 0.4),
        0 20px 50px rgba(102, 126, 234, 0.25),
        inset 0 1px 0 rgba(255, 255, 255, 0.15);
    border-color: rgba(102, 126, 234, 0.4);
}

.lesson-card a {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-lg) var(--spacing-xl);
    text-decoration: none;
    color: inherit;
    position: relative;
    border-radius: var(--radius-md);
    overflow: hidden;
    min-height: 110px;
    z-index: 1;
}

.lesson-content-wrapper {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
    width: 100%;
    text-align: center;
}

.lesson-number {
    flex-shrink: 0;
    width: 70px;
    height: 70px;
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, var(--accent), var(--secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1rem;
    color: white;
    box-shadow: 0 4px 20px rgba(0, 212, 170, 0.4), inset 0 1px 0 rgba(255, 255, 255, 0.2);
    animation: float 3s ease-in-out infinite;
    position: relative;
    border: 2px solid rgba(255, 255, 255, 0.1);
}

.lesson-number::before {
    content: '';
    position: absolute;
    inset: -2px;
    border-radius: var(--radius-full);
    padding: 2px;
    background: linear-gradient(135deg, var(--accent), var(--secondary));
    -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
    opacity: 0;
    transition: opacity var(--transition-base);
}

.lesson-card:hover .lesson-number::before {
    opacity: 0.3;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-5px); }
}

.lesson-title {
    display: block;
    font-size: clamp(1.1rem, 2.5vw, 1.25rem);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
    line-height: 1.4;
    font-family: var(--font-primary);
}

.lesson-desc {
    display: block;
    color: var(--text-secondary);
    font-size: clamp(0.9rem, 2vw, 0.95rem);
    line-height: 1.6;
}

.lesson-progress {
    flex-shrink: 0;
    background: linear-gradient(135deg, rgba(0, 212, 170, 0.15), rgba(102, 126, 234, 0.1));
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 600;
    min-width: 60px;
    text-align: center;
    border: 1px solid rgba(0, 212, 170, 0.2);
    color: var(--accent);
    box-shadow: 0 2px 8px rgba(0, 212, 170, 0.1);
    align-self: center;
}

.lesson-checkmark {
    flex-shrink: 0;
    width: 36px;
    height: 36px;
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, var(--success), #40c057);
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    color: white;
    box-shadow: 0 4px 20px rgba(81, 207, 102, 0.4), inset 0 1px 0 rgba(255, 255, 255, 0.2);
    animation: pulse 2s infinite;
    border: 2px solid rgba(255, 255, 255, 0.1);
    align-self: center;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

/* Progress Overview */
#progress-overview {
    margin-top: 0;
    padding: var(--spacing-xl);
    background: linear-gradient(135deg, rgba(0, 212, 170, 0.08), rgba(102, 126, 234, 0.04));
    backdrop-filter: blur(18px);
    border: 1px solid rgba(0, 212, 170, 0.18);
    border-radius: var(--radius-lg);
    position: relative;
    overflow: hidden;
    box-shadow: 0 10px 36px rgba(0, 0, 0, 0.35), inset 0 1px 0 rgba(255, 255, 255, 0.1);
    width: 100%;
}

#progress-overview::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--accent), var(--key-back));
}

#progress-overview h2 {
    margin-bottom: 1.25rem;
    font-size: 1.4rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
}

#progress-overview .progress-bar {
    width: 100%;
    height: 32px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 16px;
    overflow: hidden;
    margin: 1.25rem 0;
    position: relative;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 
        inset 0 2px 4px rgba(0, 0, 0, 0.2),
        0 2px 8px rgba(0, 0, 0, 0.1);
}

#progress-overview .progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent), #20c997, var(--accent));
    background-size: 200% 100%;
    transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    font-size: 0.9rem;
    width: 0%;
    animation: shimmer 3s infinite linear;
    border-radius: 16px;
    position: relative;
    overflow: hidden;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
    box-shadow: 
        0 2px 8px rgba(0, 212, 170, 0.4),
        inset 0 1px 0 rgba(255, 255, 255, 0.3);
}

/* Progress fill shine effect */
#progress-overview .progress-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 50%;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.25), transparent);
    border-radius: 16px 16px 0 0;
}

/* Completion celebration */
#progress-overview .progress-fill.complete {
    background: linear-gradient(90deg, #20c997, #51cf66, #20c997);
}

#progress-overview p {
    margin-top: 0.75rem;
    text-align: left;
    color: var(--text-low);
    font-size: 0.95rem;
}

/* Module Sections */
.module {
    margin-bottom: 3rem;
    animation: slideInLeft 0.6s ease-out;
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    padding: 0;
    position: relative;
    overflow: hidden;
}

/* Module decorative glow */
.module::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at left center, rgba(0, 212, 170, 0.05) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

.module h2 {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: clamp(1.3rem, 3vw, 1.6rem);
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md) var(--spacing-lg);
    background: linear-gradient(135deg, rgba(0, 212, 170, 0.08), rgba(102, 126, 234, 0.04));
    backdrop-filter: blur(15px);
    border: 1px solid rgba(0, 212, 170, 0.15);
    border-left: 4px solid var(--accent);
    border-radius: var(--radius-md);
    box-shadow: 
        0 4px 20px rgba(0, 0, 0, 0.2), 
        inset 0 1px 0 rgba(255, 255, 255, 0.05);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    font-weight: 600;
    position: relative;
    overflow: hidden;
    z-index: 1;
}

/* Shine effect on module heading */
.module h2::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    transition: left 0.5s ease;
}

.module h2:hover::after {
    left: 100%;
}

.module h2::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--accent), var(--secondary));
    transition: width 0.3s ease;
}

.module h2:hover {
    transform: translateX(4px);
    box-shadow: 0 8px 32px rgba(0, 212, 170, 0.2), inset 0 1px 0 rgba(255, 255, 255, 0.1);
    border-left-width: 6px;
}

.module h2:hover::before {
    width: 6px;
}

.module .lessons-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    list-style: none;
    padding: 0;
    width: 100%;
    margin: 0;
}

/* Enhanced Responsive Design */
@media (max-width: 768px) {
    #mainnav {
        gap: var(--spacing-lg);
    }
    
    .module {
        margin-bottom: var(--spacing-lg);
    }
    
    .module h2 {
        font-size: clamp(1.1rem, 4vw, 1.3rem);
        padding: var(--spacing-md) var(--spacing-lg);
        margin-bottom: var(--spacing-md);
    }
    
    .lessons-list {
        gap: var(--spacing-md);
        padding: 0;
    }
    
    .lesson-card {
        margin: 0;
        border-radius: var(--radius-md);
    }
    
    .lesson-card a {
        padding: var(--spacing-md) var(--spacing-lg);
        gap: var(--spacing-sm);
        min-height: auto;
        flex-wrap: wrap;
    }
    
    .lesson-number {
        width: 50px;
        height: 50px;
        font-size: 0.95rem;
    }
    
    .lesson-title {
        font-size: 1rem;
    }
    
    .lesson-desc {
        font-size: 0.85rem;
    }
    
    .lesson-progress {
        padding: 0.35rem 0.7rem;
        font-size: 0.75rem;
        min-width: 40px;
    }
    
    .lesson-checkmark {
        width: 28px;
        height: 28px;
        font-size: 1rem;
    }
    
    #progress-overview {
        padding: var(--spacing-lg);
        margin: 0;
    }
    
    #progress-overview h2 {
        font-size: clamp(1.1rem, 4vw, 1.3rem);
    }
    
    .lesson-nav {
        padding: var(--spacing-sm) var(--spacing-md);
        flex-wrap: wrap;
    }
    
    .lesson-header {
        padding: var(--spacing-md) 0;
    }
    
    .lesson-meta {
        flex-direction: column;
        gap: var(--spacing-xs);
    }
    
    .lesson-meta span {
        font-size: 0.8rem;
        padding: 0.4rem 0.8rem;
    }
    
    .lesson-content section {
        padding: var(--spacing-md);
    }
    
    .lesson-footer {
        flex-direction: column;
    }
    
    /* Disable tilt effect on mobile */
    .tilt-card:hover {
        transform: translateY(-2px);
    }
}

/* Grid layout for lesson cards on larger screens */
@media (min-width: 900px) {
    .module .lessons-list {
        display: grid;
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: var(--spacing-lg);
    }
}

@media (max-width: 480px) {
    body {
        padding: var(--spacing-sm);
        gap: var(--spacing-md);
    }
    
    header {
        padding: var(--spacing-md) var(--spacing-sm);
    }
    
    .lesson-card a {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }
    
    .lesson-content-wrapper {
        text-align: center;
    }
    
    .lesson-progress,
    .lesson-checkmark {
        align-self: center;
    }
}

/* Tablet and larger screens - maintain vertical layout */
@media (min-width: 769px) {
    .lessons-list {
        gap: 2rem;
        max-width: 800px;
        margin: 0 auto;
    }
    
    .lesson-card a {
        flex-direction: column;
        align-items: center;
        padding: 2rem 2.5rem;
    }
    
    .lesson-progress,
    .lesson-checkmark {
        align-self: center;
    }
}

/* Large screens */
@media (min-width: 1200px) {
    body {
        max-width: 80rem;
    }
    
    .lessons-list {
        max-width: 900px;
    }
}

/* ============================================
   ACCESSIBILITY & ANIMATIONS
   ============================================ */

/* Enhanced focus states */
*:focus {
    outline: 3px solid var(--accent);
    outline-offset: 2px;
    border-radius: 4px;
}

.lesson-card:focus-within {
    outline: 3px solid var(--accent);
    outline-offset: 4px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --back: #000000;
        --text: #ffffff;
        --accent: #00ff00;
        --border: #ffffff;
    }
    
    .lesson-card {
        border: 2px solid var(--border);
        background: var(--back);
    }
}

/* Reduced motion preferences */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    .lesson-number {
        animation: none;
    }
    
    .lesson-checkmark {
        animation: none;
    }
    
    .progress-fill {
        animation: none;
    }
}

/* Custom tooltip system */
[data-tooltip] {
    position: relative;
}

[data-tooltip]:before {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.9);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    font-size: 0.8rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
    margin-bottom: 5px;
    z-index: 1000;
}

[data-tooltip]:hover:before {
    opacity: 1;
}

/* Loading states */
.lesson-card.loading {
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: loading 1.5s infinite;
}

@keyframes loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

.quiz-question.loading {
    opacity: 0.6;
    pointer-events: none;
}

/* Intersection Observer animation classes */
.animate-in {
    animation: slideInUp 0.6s ease-out;
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}