/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #333;
    overflow-x: hidden;
}

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

/* Navigation */
.navbar {
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    box-shadow: 0 2px 20px rgba(0,0,0,0.1);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo h1 {
    color: white;
    font-size: 1.5rem;
    font-weight: 600;
}

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

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

.nav-link:hover {
    color: #ffd700;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.bar {
    width: 25px;
    height: 3px;
    background-color: white;
    margin: 3px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 120px 20px 80px;
    display: flex;
    align-items: center;
    min-height: 100vh;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

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

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

.btn-primary, .btn-secondary {
    padding: 15px 30px;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    display: inline-block;
}

.btn-primary {
    background: #ff6b6b;
    color: white;
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn-primary:hover, .btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

/* Thermal Demo Visual */
.thermal-demo {
    background: rgba(255,255,255,0.1);
    padding: 2rem;
    border-radius: 15px;
    backdrop-filter: blur(10px);
}

.thermal-image-placeholder {
    width: 100%;
    height: 300px;
    background: linear-gradient(45deg, #ff0000, #ff8800, #ffff00, #00ff00, #0088ff, #0000ff);
    border-radius: 10px;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}

.thermal-gradient {
    width: 80%;
    height: 80%;
    background: radial-gradient(circle at center, #ff0000 0%, #ff8800 25%, #ffff00 50%, #00ff00 75%, #0000ff 100%);
    border-radius: 10px;
    opacity: 0.8;
}

.temperature-scale {
    position: absolute;
    right: 15px;
    top: 15px;
    bottom: 15px;
    width: 60px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
}

.temp-label {
    color: white;
    font-weight: 600;
    font-size: 0.9rem;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.7);
    background: rgba(0,0,0,0.3);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
}

.scale-bar {
    display: flex;
    flex-direction: column;
    gap: 2px;
    flex-grow: 1;
    margin: 10px 0;
    width: 20px;
}

.scale-marker {
    height: 100%;
    border-radius: 2px;
    border: 1px solid rgba(255,255,255,0.3);
}

/* Sections */
.section {
    padding: 80px 0;
}

.bg-light {
    background: #f8f9fa;
}

.section h2 {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 3rem;
    color: #2c3e50;
}

/* Content Grid */
.content-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.content-text p {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    color: #555;
}

.content-text h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.feature-list {
    list-style: none;
    padding: 0;
}

.feature-list li {
    padding: 0.75rem 0;
    border-bottom: 1px solid #eee;
}

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

.feature-list strong {
    color: #2c3e50;
}

/* Visual Examples */
.comparison-box {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.image-compare {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.image-compare h4 {
    text-align: center;
    margin-bottom: 1rem;
    color: #2c3e50;
}

.placeholder-image {
    height: 200px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 600;
}

.placeholder-image.normal {
    background: linear-gradient(45deg, #4a4a4a, #8a8a8a);
}

.placeholder-image.thermal {
    background: linear-gradient(45deg, #ff0000, #ff8800, #ffff00, #00ff00, #0000ff);
}

/* Science Section */
.science-content {
    display: flex;
    flex-direction: column;
    gap: 3rem;
}

.science-principle {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.science-principle h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.science-principle p {
    color: #555;
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
}

/* Spectrum Visual */
.spectrum-visual {
    margin: 1.5rem 0;
}

.spectrum-bar {
    display: flex;
    height: 60px;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.spectrum-section {
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 600;
    font-size: 0.9rem;
}

.spectrum-section.visible {
    background: linear-gradient(90deg, #ff0000, #ff8800, #ffff00, #00ff00, #0088ff, #0000ff, #8000ff);
    flex: 1;
}

.spectrum-section.infrared {
    background: linear-gradient(90deg, #8b0000, #ff0000);
    flex: 2;
}

/* Formula */
.formula {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid #667eea;
}

.formula p {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: #2c3e50;
}

.formula-legend {
    list-style: none;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
}

.formula-legend li {
    font-size: 0.95rem;
    color: #555;
}

/* Practical Examples */
.practical-examples {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid #eee;
}

.practical-examples h4 {
    color: #2c3e50;
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
}

.example-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.example-card {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid #667eea;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.example-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
}

.example-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
    text-align: center;
}

.example-card h5 {
    color: #2c3e50;
    margin-bottom: 1rem;
    font-size: 1.1rem;
    text-align: center;
}

.example-card p {
    color: #555;
    margin: 0;
    line-height: 1.6;
    font-size: 0.95rem;
}

.example-card strong {
    color: #667eea;
    font-weight: 600;
}

.key-insight {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    padding: 2rem;
    border-radius: 15px;
    margin-top: 2rem;
}

.key-insight h5 {
    color: white;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.key-insight p {
    color: white;
    margin: 0;
    line-height: 1.6;
    opacity: 0.95;
}

/* Distance Examples */
.distance-examples {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid #eee;
}

.distance-examples h4 {
    color: #2c3e50;
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
}

.distance-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.distance-card {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid #17a2b8;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.distance-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
}

.distance-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
    text-align: center;
}

.distance-card h5 {
    color: #17a2b8;
    margin-bottom: 1rem;
    font-size: 1.1rem;
    text-align: center;
}

.distance-card p {
    color: #555;
    margin: 0;
    line-height: 1.6;
    font-size: 0.95rem;
}

.distance-best-practices {
    background: linear-gradient(135deg, #17a2b8, #138496);
    color: white;
    padding: 2rem;
    border-radius: 15px;
    margin-top: 2rem;
}

.distance-best-practices h5 {
    color: white;
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
}

.practice-list {
    display: grid;
    gap: 1rem;
}

.practice-item {
    background: rgba(255, 255, 255, 0.1);
    padding: 1rem;
    border-radius: 8px;
    border-left: 4px solid rgba(255, 255, 255, 0.3);
}

.practice-item strong {
    color: #fff;
    display: block;
    margin-bottom: 0.5rem;
}

.practice-item {
    color: rgba(255, 255, 255, 0.9);
    line-height: 1.5;
}

/* Process Steps */
.process-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.step {
    text-align: center;
    padding: 1.5rem;
    background: #f8f9fa;
    border-radius: 10px;
    transition: transform 0.3s ease;
}

.step:hover {
    transform: translateY(-5px);
}

.step-number {
    width: 50px;
    height: 50px;
    background: #667eea;
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 600;
    margin: 0 auto 1rem;
}

.step h4 {
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

.step p {
    color: #555;
    font-size: 0.95rem;
}

/* Emissivity Examples */
.emissivity-examples {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-top: 2rem;
}

.material-card {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid #667eea;
}

.material-card h5 {
    color: #2c3e50;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.material-card ul {
    list-style: none;
}

.material-card li {
    padding: 0.25rem 0;
    color: #555;
}

.material-card li:before {
    content: "•";
    color: #667eea;
    font-weight: bold;
    margin-right: 0.5rem;
}

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

.application-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.application-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0,0,0,0.15);
}

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

.application-card h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.application-card p {
    color: #555;
    margin-bottom: 1.5rem;
}

.application-card ul {
    list-style: none;
}

.application-card li {
    padding: 0.5rem 0;
    color: #666;
    border-bottom: 1px solid #eee;
}

.application-card li:last-child {
    border-bottom: none;
}

.application-card li:before {
    content: "✓";
    color: #28a745;
    font-weight: bold;
    margin-right: 0.5rem;
}

/* Benefits Section */
.benefits-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.benefit-category {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.benefit-category h3 {
    color: #2c3e50;
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.benefit-category ul {
    list-style: none;
}

.benefit-category li {
    padding: 0.75rem 0;
    border-bottom: 1px solid #eee;
    color: #555;
}

.benefit-category li:last-child {
    border-bottom: none;
}

.benefit-category strong {
    color: #2c3e50;
}

/* ROI Section */
.roi-section {
    background: white;
    padding: 3rem;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    text-align: center;
}

.roi-section h3 {
    color: #2c3e50;
    margin-bottom: 2rem;
    font-size: 2rem;
}

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

.roi-benefit {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    text-align: left;
    padding: 1.5rem;
    background: #f8f9fa;
    border-radius: 10px;
    transition: transform 0.3s ease;
}

.roi-benefit:hover {
    transform: translateY(-5px);
}

.benefit-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.benefit-content h4 {
    color: #2c3e50;
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
}

.benefit-content p {
    color: #555;
    margin: 0;
    line-height: 1.6;
}

.roi-note {
    background: #e8f4f8;
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid #17a2b8;
    text-align: left;
}

.roi-note p {
    margin: 0;
    color: #495057;
    line-height: 1.6;
}

/* Quiz Styles */
#quiz-container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    padding: 3rem;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.quiz-screen h3 {
    color: #2c3e50;
    margin-bottom: 1.5rem;
    font-size: 2rem;
    text-align: center;
}

#quiz-start p {
    text-align: center;
    color: #555;
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

#start-quiz-btn {
    display: block;
    margin: 0 auto;
}

.quiz-progress {
    margin-bottom: 2rem;
}

.progress-bar {
    width: 100%;
    height: 10px;
    background: #e9ecef;
    border-radius: 5px;
    overflow: hidden;
    margin-bottom: 1rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #667eea, #764ba2);
    width: 0%;
    transition: width 0.3s ease;
}

#question-counter {
    color: #555;
    font-weight: 500;
}

#question-text {
    color: #2c3e50;
    margin-bottom: 2rem;
    font-size: 1.3rem;
    line-height: 1.5;
}

.answer-options {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 2rem;
}

.answer-option {
    background: #f8f9fa;
    border: 2px solid #e9ecef;
    padding: 1rem 1.5rem;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.1rem;
}

.answer-option:hover {
    background: #e9ecef;
    border-color: #667eea;
}

.answer-option.selected {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.answer-option.correct {
    background: #28a745;
    color: white;
    border-color: #28a745;
}

.answer-option.incorrect {
    background: #dc3545;
    color: white;
    border-color: #dc3545;
}

.quiz-controls {
    text-align: center;
}

.score-display {
    text-align: center;
    margin-bottom: 2rem;
}

.score-circle {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    font-size: 2rem;
    font-weight: 700;
}

.score-text {
    font-size: 1.2rem;
    color: #2c3e50;
    margin-bottom: 1rem;
}

.results-feedback {
    background: #f8f9fa;
    padding: 2rem;
    border-radius: 10px;
    margin-bottom: 2rem;
}

.results-feedback h4 {
    color: #2c3e50;
    margin-bottom: 1rem;
}

.results-feedback p {
    color: #555;
    line-height: 1.6;
}

/* Citations Section */
.citations-content {
    max-width: 1000px;
    margin: 0 auto;
}

.citation-notice {
    background: #fff3cd;
    border: 1px solid #ffeaa7;
    border-radius: 10px;
    padding: 1.5rem;
    margin-bottom: 3rem;
    border-left: 4px solid #f39c12;
}

.citation-notice p {
    margin: 0;
    color: #856404;
    font-weight: 500;
}

.citations-grid {
    display: flex;
    flex-direction: column;
    gap: 3rem;
    margin-bottom: 3rem;
}

.citation-category {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.citation-category h3 {
    color: #2c3e50;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    border-bottom: 2px solid #667eea;
    padding-bottom: 0.5rem;
}

.citation-item {
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid #eee;
}

.citation-item:last-child {
    margin-bottom: 0;
    border-bottom: none;
    padding-bottom: 0;
}

.citation-item h4 {
    color: #667eea;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.citation-item p {
    color: #555;
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

.citation-item strong {
    color: #2c3e50;
}

.citation-item a {
    color: #667eea;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.citation-item a:hover {
    color: #4c63d2;
    text-decoration: underline;
}

.citation-item a:visited {
    color: #5a67d8;
}

.important-note {
    background: #f8f9fa;
    padding: 2rem;
    border-radius: 15px;
    border-left: 4px solid #dc3545;
    margin-bottom: 2rem;
}

.important-note h3 {
    color: #dc3545;
    margin-bottom: 1.5rem;
    font-size: 1.4rem;
}

.important-note ul {
    list-style: none;
    padding: 0;
}

.important-note li {
    padding: 0.75rem 0;
    border-bottom: 1px solid #dee2e6;
    color: #555;
}

.important-note li:last-child {
    border-bottom: none;
}

.important-note li:before {
    content: "⚠️";
    margin-right: 0.5rem;
}

.educational-disclaimer {
    background: #e8f4f8;
    padding: 2rem;
    border-radius: 15px;
    border-left: 4px solid #17a2b8;
}

.educational-disclaimer h3 {
    color: #17a2b8;
    margin-bottom: 1.5rem;
    font-size: 1.4rem;
}

.educational-disclaimer p {
    color: #495057;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.educational-disclaimer p:last-child {
    margin-bottom: 0;
    font-size: 0.9rem;
    color: #6c757d;
}

/* Footer */
footer {
    background: #2c3e50;
    color: white;
    text-align: center;
    padding: 2rem 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: #1e3c72;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 2.5rem;
    }
    
    .content-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .image-compare {
        grid-template-columns: 1fr;
    }
    
    .process-steps {
        grid-template-columns: 1fr;
    }
    
    .emissivity-examples {
        grid-template-columns: 1fr;
    }
    
    .applications-grid {
        grid-template-columns: 1fr;
    }
    
    .benefits-content {
        grid-template-columns: 1fr;
    }
    
    .roi-stats {
        grid-template-columns: 1fr;
    }
    
    .roi-benefits {
        grid-template-columns: 1fr;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .formula-legend {
        grid-template-columns: 1fr;
    }
    
    .example-grid {
        grid-template-columns: 1fr;
    }
    
    .distance-grid {
        grid-template-columns: 1fr;
    }
    
    .key-insight {
        padding: 1.5rem;
    }
    
    .distance-best-practices {
        padding: 1.5rem;
    }
    
    .citations-grid {
        gap: 2rem;
    }
    
    .citation-category {
        padding: 1.5rem;
    }
    
    .important-note,
    .educational-disclaimer {
        padding: 1.5rem;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .section h2 {
        font-size: 2rem;
    }
    
    #quiz-container {
        padding: 2rem 1rem;
    }
    
    .btn-primary, .btn-secondary {
        padding: 12px 24px;
        font-size: 1rem;
    }
}

/* Smooth Scrolling */
html {
    scroll-behavior: smooth;
}

/* Animation Classes */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Loading Animation */
@keyframes pulse {
    0% { opacity: 1; }
    50% { opacity: 0.5; }
    100% { opacity: 1; }
}

.loading {
    animation: pulse 1.5s infinite;
}