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

:root {
    --primary-pink: #ff6b9d;
    --oxygen-blue: #4ecdc4;
    --light-mint: #95e1d3;
    --blood-red: #f38181;
    --warm-yellow: #ffeaa7;
    --dark-text: #2d3436;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
}

body {
    font-family: 'Inter', sans-serif;
    color: var(--dark-text);
    line-height: 1.6;
    background-color: var(--light-bg);
}

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

/* Header Styles */
.header {
    background: linear-gradient(135deg, var(--primary-pink), var(--blood-red));
    color: var(--white);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.5rem;
    font-weight: 700;
}

.logo i {
    font-size: 2rem;
}

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

.nav a {
    color: var(--white);
    text-decoration: none;
    font-weight: 500;
    transition: opacity 0.3s ease;
}

.nav a:hover {
    opacity: 0.8;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--oxygen-blue), var(--light-mint));
    color: var(--white);
    padding: 4rem 0;
    text-align: center;
}

.hero-content {
    animation: fadeInUp 1s ease;
}

.page-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.tagline {
    font-size: 1.3rem;
    margin-bottom: 2rem;
    opacity: 0.95;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.stat-card {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    padding: 1.5rem;
    border-radius: 15px;
    min-width: 200px;
    transition: transform 0.3s ease;
}

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

.stat-card i {
    font-size: 2.5rem;
    display: block;
    margin-bottom: 0.5rem;
}

.stat-number {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.stat-label {
    display: block;
    font-size: 0.9rem;
    opacity: 0.9;
}

/* Section Styles */
.section {
    padding: 4rem 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--primary-pink);
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 100px;
    height: 4px;
    background: var(--oxygen-blue);
    margin: 1rem auto 0;
    border-radius: 2px;
}

/* Overview Section */
.overview-section {
    background: var(--white);
}

.overview-content {
    max-width: 900px;
    margin: 0 auto;
    font-size: 1.2rem;
    line-height: 1.8;
    text-align: center;
    padding: 2rem;
    background: linear-gradient(135deg, rgba(255, 107, 157, 0.1), rgba(78, 205, 196, 0.1));
    border-radius: 15px;
    border-left: 5px solid var(--primary-pink);
}

/* Location Section */
.location-section {
    background: var(--light-bg);
}

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

.content-box {
    background: var(--white);
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
}

.icon-large {
    font-size: 3rem;
    color: var(--primary-pink);
    margin-bottom: 1rem;
}

.content-box h3 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    color: var(--oxygen-blue);
}

.info-list {
    list-style: none;
}

.info-list li {
    padding: 0.8rem 0;
    padding-left: 1.5rem;
    position: relative;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

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

.info-list li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--oxygen-blue);
    font-weight: 700;
}

.info-list strong {
    color: var(--primary-pink);
}

.visual-box {
    display: flex;
    justify-content: center;
    align-items: center;
}

.lung-animation {
    text-align: center;
}

.breathing-icon {
    font-size: 15rem;
    color: var(--primary-pink);
    animation: breathing 3s ease-in-out infinite;
}

.animation-label {
    font-size: 1.2rem;
    color: var(--dark-text);
    margin-top: 1rem;
    font-weight: 600;
}

@keyframes breathing {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
    }
    50% {
        transform: scale(1.1);
        opacity: 0.8;
    }
}

/* Structure Section */
.structure-section {
    background: var(--white);
}

.structure-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.structure-card {
    background: linear-gradient(135deg, var(--light-bg), var(--white));
    padding: 2rem;
    border-radius: 15px;
    border-left: 5px solid var(--oxygen-blue);
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
}

.structure-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.structure-card i {
    font-size: 2.5rem;
    color: var(--primary-pink);
    margin-bottom: 1rem;
}

.structure-card h3 {
    font-size: 1.4rem;
    margin-bottom: 1rem;
    color: var(--oxygen-blue);
}

/* Functions Section */
.functions-section {
    background: linear-gradient(135deg, rgba(149, 225, 211, 0.3), rgba(78, 205, 196, 0.3));
}

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

.function-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 15px;
    text-align: center;
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
}

.function-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
}

.function-card i {
    font-size: 3rem;
    color: var(--oxygen-blue);
    margin-bottom: 1rem;
}

.function-card h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--primary-pink);
}

.function-card.highlight {
    background: linear-gradient(135deg, var(--primary-pink), var(--blood-red));
    color: var(--white);
}

.function-card.highlight i,
.function-card.highlight h3 {
    color: var(--white);
}

/* Breathing Section */
.breathing-section {
    background: var(--white);
}

.breathing-container {
    max-width: 1000px;
    margin: 0 auto;
}

.breathing-process {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 2rem;
}

.process-card {
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
}

.process-card.inhalation {
    background: linear-gradient(135deg, rgba(78, 205, 196, 0.2), rgba(149, 225, 211, 0.2));
    border: 3px solid var(--oxygen-blue);
}

.process-card.exhalation {
    background: linear-gradient(135deg, rgba(255, 107, 157, 0.2), rgba(243, 129, 129, 0.2));
    border: 3px solid var(--primary-pink);
}

.process-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.process-card.inhalation h3 {
    color: var(--oxygen-blue);
}

.process-card.exhalation h3 {
    color: var(--primary-pink);
}

.process-steps {
    list-style: none;
    counter-reset: step-counter;
}

.process-steps li {
    padding: 1rem 0;
    padding-left: 2.5rem;
    position: relative;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.process-steps li:last-child {
    border-bottom: none;
}

.process-steps li::before {
    counter-increment: step-counter;
    content: counter(step-counter);
    position: absolute;
    left: 0;
    top: 1rem;
    width: 30px;
    height: 30px;
    background: var(--oxygen-blue);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.9rem;
}

.process-card.exhalation .process-steps li::before {
    background: var(--primary-pink);
}

.breathing-note {
    background: var(--warm-yellow);
    padding: 1.5rem;
    border-radius: 15px;
    display: flex;
    gap: 1rem;
    align-items: flex-start;
}

.breathing-note i {
    font-size: 2rem;
    color: var(--blood-red);
    flex-shrink: 0;
}

/* Comparison Section */
.comparison-section {
    background: var(--light-bg);
}

.comparison-table {
    background: var(--white);
    border-radius: 15px;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.comparison-header {
    display: grid;
    grid-template-columns: 1fr 1fr;
    background: linear-gradient(135deg, var(--primary-pink), var(--blood-red));
    color: var(--white);
}

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

.compare-item i {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.compare-item h3 {
    font-size: 1.8rem;
}

.comparison-row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    transition: background 0.3s ease;
}

.comparison-row:hover {
    background: rgba(78, 205, 196, 0.05);
}

.comparison-row:last-child {
    border-bottom: none;
}

.compare-feature {
    padding: 1.5rem;
    font-weight: 600;
    background: var(--light-bg);
    display: flex;
    align-items: center;
}

.compare-value {
    padding: 1.5rem;
    display: flex;
    align-items: center;
}

.compare-value.left {
    background: rgba(78, 205, 196, 0.05);
}

.compare-value.right {
    background: rgba(255, 107, 157, 0.05);
}

/* Gas Exchange Section */
.gas-exchange-section {
    background: var(--white);
}

.gas-exchange-content {
    max-width: 1100px;
    margin: 0 auto;
}

.exchange-explanation {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 3rem;
}

.exchange-card {
    background: linear-gradient(135deg, var(--light-bg), var(--white));
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
}

.exchange-card i {
    font-size: 3rem;
    color: var(--oxygen-blue);
    margin-bottom: 1rem;
}

.exchange-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: var(--primary-pink);
}

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

.exchange-card ul li {
    padding: 0.7rem 0;
    padding-left: 1.5rem;
    position: relative;
}

.exchange-card ul li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--oxygen-blue);
    font-weight: 700;
}

.exchange-details {
    background: linear-gradient(135deg, rgba(78, 205, 196, 0.1), rgba(149, 225, 211, 0.1));
    padding: 2rem;
    border-radius: 15px;
    border: 2px solid var(--oxygen-blue);
}

.exchange-details h3 {
    font-size: 1.8rem;
    margin-bottom: 2rem;
    color: var(--primary-pink);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.detail-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.detail-item {
    background: var(--white);
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid var(--oxygen-blue);
}

.detail-item strong {
    display: block;
    color: var(--primary-pink);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

/* Diseases Section */
.diseases-section {
    background: var(--light-bg);
}

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

.disease-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    border-top: 4px solid var(--blood-red);
}

.disease-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.disease-card i {
    font-size: 2.5rem;
    color: var(--blood-red);
    margin-bottom: 1rem;
}

.disease-card h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--primary-pink);
}

.safety-note {
    background: var(--warm-yellow);
    padding: 1.5rem;
    border-radius: 15px;
    border-left: 5px solid var(--blood-red);
    display: flex;
    gap: 1rem;
    align-items: flex-start;
}

.safety-note i {
    font-size: 2rem;
    color: var(--blood-red);
    flex-shrink: 0;
}

/* Health Tips Section */
.health-tips-section {
    background: var(--white);
}

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

.tip-card {
    background: linear-gradient(135deg, var(--light-mint), var(--white));
    padding: 2rem;
    border-radius: 15px;
    text-align: center;
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
    border-top: 4px solid var(--oxygen-blue);
}

.tip-card:hover {
    transform: translateY(-5px) scale(1.02);
    box-shadow: var(--shadow-lg);
}

.tip-card i {
    font-size: 2.5rem;
    color: var(--oxygen-blue);
    margin-bottom: 1rem;
}

.tip-card h3 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--primary-pink);
}

/* Fun Facts Section */
.fun-facts-section {
    background: linear-gradient(135deg, rgba(255, 234, 167, 0.3), rgba(243, 129, 129, 0.3));
}

.facts-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.fact-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    display: flex;
    gap: 1rem;
    align-items: flex-start;
    border-left: 4px solid var(--warm-yellow);
}

.fact-card:hover {
    transform: translateX(10px);
    box-shadow: var(--shadow-lg);
    border-left-color: var(--primary-pink);
}

.fact-card i {
    font-size: 2rem;
    color: var(--oxygen-blue);
    flex-shrink: 0;
}

.fact-card strong {
    color: var(--primary-pink);
}

/* Quiz Section */
.quiz-section {
    background: var(--white);
}

.quiz-container {
    max-width: 800px;
    margin: 0 auto;
}

.quiz-question {
    background: var(--light-bg);
    padding: 2rem;
    border-radius: 15px;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

.quiz-question h3 {
    color: var(--primary-pink);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.quiz-question p {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.quiz-options {
    display: grid;
    gap: 1rem;
}

.quiz-option {
    background: var(--white);
    border: 2px solid var(--oxygen-blue);
    padding: 1rem 1.5rem;
    border-radius: 10px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: left;
}

.quiz-option:hover {
    background: var(--oxygen-blue);
    color: var(--white);
    transform: translateX(5px);
}

.quiz-option.correct {
    background: #2ecc71;
    color: var(--white);
    border-color: #2ecc71;
}

.quiz-option.incorrect {
    background: #e74c3c;
    color: var(--white);
    border-color: #e74c3c;
}

.quiz-feedback {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: 10px;
    font-weight: 500;
}

.quiz-feedback.correct {
    background: #d4edda;
    color: #155724;
    border-left: 4px solid #2ecc71;
}

.quiz-feedback.incorrect {
    background: #f8d7da;
    color: #721c24;
    border-left: 4px solid #e74c3c;
}

.quiz-results {
    text-align: center;
    margin-top: 3rem;
}

.btn-show-answers {
    background: linear-gradient(135deg, var(--primary-pink), var(--blood-red));
    color: var(--white);
    border: none;
    padding: 1rem 2rem;
    font-size: 1.1rem;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
}

.btn-show-answers:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.answer-key {
    background: var(--light-bg);
    padding: 2rem;
    border-radius: 15px;
    margin-top: 2rem;
    text-align: left;
    box-shadow: var(--shadow);
}

.answer-key h3 {
    color: var(--primary-pink);
    margin-bottom: 1rem;
}

.answer-key ul {
    list-style: none;
}

.answer-key li {
    padding: 0.8rem 0;
    padding-left: 2rem;
    position: relative;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.answer-key li:last-child {
    border-bottom: none;
}

.answer-key li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: #2ecc71;
    font-weight: 700;
    font-size: 1.2rem;
}

/* Diagram Section */
.diagram-section {
    background: var(--light-bg);
}

.diagram-content {
    max-width: 1000px;
    margin: 0 auto;
}

.diagram-instructions {
    background: var(--white);
    padding: 3rem;
    border-radius: 15px;
    box-shadow: var(--shadow-lg);
}

.diagram-instructions h3 {
    color: var(--primary-pink);
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.instruction-step {
    background: var(--light-bg);
    padding: 1.5rem;
    border-radius: 10px;
    margin-bottom: 1.5rem;
    border-left: 4px solid var(--oxygen-blue);
}

.instruction-step strong {
    display: block;
    color: var(--primary-pink);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.labels-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
    margin: 2rem 0;
}

.label-item {
    background: var(--light-bg);
    padding: 1rem;
    border-radius: 10px;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.label-item i {
    color: #2ecc71;
}

.diagram-tips {
    background: linear-gradient(135deg, rgba(78, 205, 196, 0.1), rgba(149, 225, 211, 0.1));
    padding: 2rem;
    border-radius: 15px;
    margin-top: 2rem;
    border: 2px dashed var(--oxygen-blue);
}

.diagram-tips h4 {
    color: var(--primary-pink);
    margin-bottom: 1rem;
    font-size: 1.3rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.diagram-tips ul {
    list-style: none;
}

.diagram-tips li {
    padding: 0.7rem 0;
    padding-left: 2rem;
    position: relative;
}

.diagram-tips li::before {
    content: '💡';
    position: absolute;
    left: 0;
}

/* Exam Notes Section */
.exam-notes-section {
    background: var(--white);
}

.exam-notes-container {
    max-width: 1100px;
    margin: 0 auto;
}

.notes-category {
    background: var(--light-bg);
    padding: 2rem;
    border-radius: 15px;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
    border-left: 5px solid var(--primary-pink);
}

.notes-category h3 {
    color: var(--primary-pink);
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.notes-list {
    list-style: none;
}

.notes-list li {
    padding: 1rem 0;
    padding-left: 2rem;
    position: relative;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    line-height: 1.7;
}

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

.notes-list li::before {
    content: '►';
    position: absolute;
    left: 0;
    color: var(--oxygen-blue);
    font-weight: 700;
}

.notes-list strong {
    color: var(--primary-pink);
}

.quick-revision-box {
    background: linear-gradient(135deg, var(--warm-yellow), rgba(243, 129, 129, 0.3));
    padding: 2rem;
    border-radius: 15px;
    border: 3px solid var(--blood-red);
    box-shadow: var(--shadow-lg);
}

.quick-revision-box h3 {
    color: var(--blood-red);
    margin-bottom: 1rem;
    font-size: 1.8rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.quick-revision-box p {
    font-size: 1.1rem;
    line-height: 1.8;
}

/* Design Suggestions Section */
.design-section {
    background: var(--light-bg);
}

.design-content {
    max-width: 1100px;
    margin: 0 auto;
}

.design-category {
    background: var(--white);
    padding: 2rem;
    border-radius: 15px;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

.design-category h3 {
    color: var(--primary-pink);
    margin-bottom: 2rem;
    font-size: 1.8rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.color-palette {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.color-item {
    text-align: center;
}

.color-swatch {
    height: 100px;
    border-radius: 10px;
    margin-bottom: 0.5rem;
    box-shadow: var(--shadow);
}

.color-item span {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--dark-text);
}

.color-item p {
    font-size: 0.9rem;
    color: #666;
}

.icon-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 2rem;
}

.icon-item {
    text-align: center;
    padding: 1.5rem;
    background: var(--light-bg);
    border-radius: 10px;
    transition: all 0.3s ease;
}

.icon-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow);
}

.icon-item i {
    font-size: 3rem;
    color: var(--oxygen-blue);
    margin-bottom: 1rem;
}

.animation-list {
    display: grid;
    gap: 1.5rem;
}

.animation-item {
    background: var(--light-bg);
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid var(--oxygen-blue);
    display: flex;
    gap: 1rem;
    align-items: flex-start;
}

.animation-item i {
    font-size: 2rem;
    color: var(--primary-pink);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--white);
    border-radius: 50%;
    flex-shrink: 0;
}

.animation-item strong {
    display: block;
    color: var(--primary-pink);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.style-guide {
    display: grid;
    gap: 1.5rem;
}

.style-item {
    background: var(--light-bg);
    padding: 1.5rem;
    border-radius: 10px;
}

.style-item strong {
    display: block;
    color: var(--primary-pink);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.layout-tips ul,
.interactive-ideas {
    display: grid;
    gap: 1rem;
}

.layout-tips li {
    background: var(--light-bg);
    padding: 1rem;
    border-radius: 10px;
    border-left: 4px solid var(--oxygen-blue);
}

.layout-tips strong {
    color: var(--primary-pink);
}

.interactive-item {
    background: var(--light-bg);
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid var(--oxygen-blue);
}

.interactive-item strong {
    display: block;
    color: var(--primary-pink);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

/* Footer */
.footer {
    background: linear-gradient(135deg, var(--dark-text), #1a1a1a);
    color: var(--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: var(--light-mint);
}

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

.footer-section ul li {
    padding: 0.5rem 0;
}

.footer-section a {
    color: var(--white);
    text-decoration: none;
    opacity: 0.8;
    transition: opacity 0.3s ease;
}

.footer-section a:hover {
    opacity: 1;
    color: var(--light-mint);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    opacity: 0.7;
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .page-title {
        font-size: 2rem;
    }

    .tagline {
        font-size: 1.1rem;
    }

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

    .hero-stats {
        flex-direction: column;
    }

    .content-grid,
    .breathing-process,
    .exchange-explanation {
        grid-template-columns: 1fr;
    }

    .comparison-header {
        grid-template-columns: 1fr;
    }

    .comparison-row {
        grid-template-columns: 1fr;
    }

    .compare-feature {
        background: var(--primary-pink);
        color: var(--white);
        font-weight: 700;
    }

    .nav {
        flex-wrap: wrap;
        gap: 1rem;
        font-size: 0.9rem;
    }

    .breathing-icon {
        font-size: 8rem;
    }

    .structure-grid,
    .functions-container,
    .diseases-grid,
    .tips-grid,
    .facts-container {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .page-title {
        font-size: 1.5rem;
    }

    .container {
        padding: 0 15px;
    }

    .section {
        padding: 2rem 0;
    }

    .breathing-icon {
        font-size: 6rem;
    }
}