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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa;
}

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

/* Header and Navigation */
header {
    background: linear-gradient(135deg, #e3f2fd, #f0f8ff);
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    max-width: 1200px;
    margin: 0 auto;
    padding-left: 20px;
    padding-right: 20px;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: #1976d2;
    text-decoration: none;
}

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

.nav-links a {
    text-decoration: none;
    color: #555;
    font-weight: 500;
    transition: color 0.3s ease;
    padding: 0.5rem 1rem;
    border-radius: 25px;
    transition: all 0.3s ease;
}

.nav-links a:hover,
.nav-links a.active {
    color: #1976d2;
    background-color: rgba(25, 118, 210, 0.1);
}

/* Hero Section */
.hero {
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: center;
    gap: 3rem;
    padding: 4rem 0;
    max-width: 1200px;
    margin: 0 auto;
    padding-left: 20px;
    padding-right: 20px;
}

.hero-content h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: #1976d2;
    line-height: 1.2;
}

.hero-content p {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    color: #666;
}

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

.btn {
    padding: 0.8rem 2rem;
    text-decoration: none;
    border-radius: 30px;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-block;
}

.btn.primary {
    background: linear-gradient(135deg, #1976d2, #42a5f5);
    color: white;
}

.btn.primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(25, 118, 210, 0.3);
}

.btn.secondary {
    background: transparent;
    color: #1976d2;
    border: 2px solid #1976d2;
}

.btn.secondary:hover {
    background: #1976d2;
    color: white;
    transform: translateY(-2px);
}

.hero-image img {
    width: 100%;
    height: auto;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

/* Features Section */
.features {
    padding: 4rem 0;
    background: linear-gradient(135deg, #fff, #f0f8ff);
}

.features h2 {
    text-align: center;
    font-size: 2.2rem;
    margin-bottom: 3rem;
    color: #1976d2;
}

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

.feature-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.feature-icon img {
    width: 80px;
    height: 80px;
    margin-bottom: 1rem;
}

.feature-card h3 {
    color: #1976d2;
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.feature-card p {
    color: #666;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.feature-card a {
    color: #1976d2;
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
}

.feature-card a:hover {
    color: #0d47a1;
}

/* Introduction Section */
.introduction {
    padding: 4rem 0;
}

.intro-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.intro-content h2 {
    font-size: 2rem;
    color: #1976d2;
    margin-bottom: 1.5rem;
}

.intro-content p {
    font-size: 1.1rem;
    color: #666;
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

/* Page Header */
.page-header {
    background: linear-gradient(135deg, #e3f2fd, #f0f8ff);
    padding: 3rem 0;
    text-align: center;
}

.page-header h1 {
    font-size: 2.5rem;
    color: #1976d2;
    margin-bottom: 1rem;
}

.page-header p {
    font-size: 1.1rem;
    color: #666;
    max-width: 600px;
    margin: 0 auto;
}

/* Experiments Grid */
.experiments-grid {
    padding: 4rem 0;
}

.experiment-card {
    background: white;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    margin-bottom: 2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.experiment-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.experiment-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.experiment-content {
    padding: 2rem;
}

.experiment-content h3 {
    color: #1976d2;
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.experiment-content p {
    color: #666;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.experiment-details {
    display: flex;
    gap: 1rem;
}

.experiment-details span {
    background: #e3f2fd;
    color: #1976d2;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

/* Observations Content */
.observations-content {
    padding: 4rem 0;
}

.observation-item {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: center;
    margin-bottom: 4rem;
    background: white;
    border-radius: 15px;
    padding: 2rem;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
}

.observation-item.reverse {
    grid-template-columns: 2fr 1fr;
}

.observation-item img {
    width: 100%;
    height: auto;
    border-radius: 10px;
}

.observation-text h3 {
    color: #1976d2;
    margin-bottom: 1rem;
    font-size: 1.4rem;
}

.observation-text p {
    color: #666;
    margin-bottom: 1rem;
    line-height: 1.6;
}

/* Concepts Grid */
.concepts-grid {
    padding: 4rem 0;
}

.concept-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    margin-bottom: 2rem;
}

.concept-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.concept-icon img {
    width: 70px;
    height: 70px;
    margin-bottom: 1rem;
}

.concept-card h3 {
    color: #1976d2;
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.concept-card p {
    color: #666;
    line-height: 1.6;
}

.concept-details {
    background: linear-gradient(135deg, #fff, #f0f8ff);
    padding: 3rem 0;
    text-align: center;
}

.concept-details h2 {
    color: #1976d2;
    margin-bottom: 2rem;
    font-size: 2rem;
}

.concept-details p {
    color: #666;
    line-height: 1.7;
    margin-bottom: 1.5rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

/* Learning Content */
.learning-content {
    padding: 4rem 0;
}

.learning-section {
    margin-bottom: 4rem;
}

.learning-section h2 {
    color: #1976d2;
    margin-bottom: 2rem;
    font-size: 2rem;
}

.strategy-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.strategy-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    transition: transform 0.3s ease;
}

.strategy-card:hover {
    transform: translateY(-3px);
}

.strategy-card h3 {
    color: #1976d2;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.strategy-card p {
    color: #666;
    line-height: 1.6;
}

.safety-tips {
    background: #fff8e1;
    padding: 2rem;
    border-radius: 15px;
    border-left: 5px solid #ff9800;
}

.safety-tips p {
    color: #666;
    margin-bottom: 1rem;
    font-weight: 500;
}

.safety-tips ul {
    color: #666;
    padding-left: 1.5rem;
}

.safety-tips li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

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

.toolkit-category {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
}

.toolkit-category h3 {
    color: #1976d2;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.toolkit-category ul {
    color: #666;
    padding-left: 1.5rem;
}

.toolkit-category li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

/* Footer */
footer {
    background: linear-gradient(135deg, #1976d2, #0d47a1);
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: 4rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .cta-buttons {
        justify-content: center;
    }
    
    .nav-links {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .observation-item,
    .observation-item.reverse {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .feature-grid,
    .strategy-grid,
    .toolkit-categories {
        grid-template-columns: 1fr;
    }
    
    .page-header h1 {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .btn {
        padding: 0.6rem 1.5rem;
        font-size: 0.9rem;
    }
    
    .features {
        padding: 2rem 0;
    }
    
    .experiments-grid,
    .observations-content,
    .concepts-grid,
    .learning-content {
        padding: 2rem 0;
    }
}