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

:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #10b981;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --bg-light: #f9fafb;
    --white: #ffffff;
    --border-color: #e5e7eb;
    --science-color: #06b6d4;
    --technology-color: #8b5cf6;
    --engineering-color: #f59e0b;
    --mathematics-color: #ec4899;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    overflow-x: hidden;
}

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

/* Navigation */
.navbar {
    background: var(--white);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
}

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

.nav-brand h1 {
    font-size: 1.75rem;
    color: var(--primary-color);
    font-weight: 700;
}

.nav-brand span {
    color: var(--secondary-color);
}

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

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

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

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

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    transition: all 0.3s;
}

/* Buttons */
.btn {
    padding: 0.625rem 1.5rem;
    border: none;
    border-radius: 6px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background: var(--primary-color);
    color: var(--white);
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
}

.btn-outline:hover {
    background: var(--primary-color);
    color: var(--white);
}

.btn-large {
    padding: 0.875rem 2rem;
    font-size: 1.05rem;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: var(--white);
    padding: 6rem 0;
    text-align: center;
}

.hero-content {
    max-width: 900px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero-title span {
    color: #fbbf24;
}

.hero-description {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    opacity: 0.95;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin-top: 3rem;
    flex-wrap: wrap;
}

.stat h3 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.stat p {
    font-size: 1rem;
    opacity: 0.9;
}

/* Features Section */
.features {
    padding: 5rem 0;
    background: var(--bg-light);
}

.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 1rem;
    font-weight: 700;
    color: var(--text-dark);
}

.section-subtitle {
    text-align: center;
    color: var(--text-light);
    font-size: 1.125rem;
    margin-bottom: 3rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.feature-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transition: all 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
}

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

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.7;
}

/* Categories Section */
.categories {
    padding: 5rem 0;
    background: var(--white);
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.grade-grid {
    grid-template-columns: repeat(2, 1fr);
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
}

.category-card {
    height: 300px;
    border-radius: 12px;
    position: relative;
    overflow: hidden;
    cursor: pointer;
    transition: transform 0.3s;
}

.category-card:hover {
    transform: scale(1.03);
}

.category-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.6);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: var(--white);
    padding: 2rem;
    text-align: center;
    transition: background 0.3s;
}

.category-card:hover .category-overlay {
    background: rgba(0, 0, 0, 0.75);
}

.category-overlay h3 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.category-overlay p {
    margin-bottom: 1.5rem;
    opacity: 0.9;
}

.category-overlay .btn {
    border-color: var(--white);
    color: var(--white);
}

.category-overlay .btn:hover {
    background: var(--white);
    color: var(--text-dark);
}

.grade-1-5 {
    background: linear-gradient(135deg, #06b6d4, #0891b2);
}

.grade-6-9 {
    background: linear-gradient(135deg, #8b5cf6, #7c3aed);
}

/* About Section */
.about {
    padding: 5rem 0;
    background: var(--bg-light);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.about-text p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    line-height: 1.8;
    font-size: 1.05rem;
}

.about-highlights {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 2rem;
}

.highlight h4 {
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.highlight p {
    color: var(--text-light);
    margin: 0;
}

.about-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.placeholder-image {
    width: 400px;
    height: 400px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 8rem;
}

/* CTA Section */
.cta {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    padding: 5rem 0;
    text-align: center;
}

.cta h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.cta p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.95;
}

.cta .btn-primary {
    background: var(--white);
    color: var(--primary-color);
}

.cta .btn-primary:hover {
    background: var(--bg-light);
}

/* Footer */
.footer {
    background: var(--text-dark);
    color: var(--white);
    padding: 3rem 0 1rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-column h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.footer-column h3 span {
    color: var(--secondary-color);
}

.footer-column h4 {
    margin-bottom: 1rem;
    font-size: 1.125rem;
}

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

.footer-column ul li {
    margin-bottom: 0.5rem;
}

.footer-column a {
    color: #d1d5db;
    text-decoration: none;
    transition: color 0.3s;
}

.footer-column a:hover {
    color: var(--white);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: #9ca3af;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: absolute;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--white);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0, 0, 0, 0.05);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .hamburger {
        display: flex;
    }

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

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

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .hero-stats {
        gap: 2rem;
    }

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

    .about-content {
        grid-template-columns: 1fr;
    }

    .placeholder-image {
        width: 300px;
        height: 300px;
        font-size: 6rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .categories-grid {
        grid-template-columns: 1fr;
    }

    .grade-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 4rem 0;
    }

    .hero-title {
        font-size: 1.75rem;
    }

    .stat h3 {
        font-size: 2rem;
    }

    .cta h2 {
        font-size: 1.75rem;
    }
}