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

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --light-bg: #f3f4f6;
    --dark-text: #1f2937;
    --light-text: #6b7280;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--dark-text);
}

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

/* Header & Navigation */
header {
    background-color: white;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar {
    padding: 1rem 0;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

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

.nav-links a {
    text-decoration: none;
    color: var(--dark-text);
    transition: color 0.3s ease;
}

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 80px 0;
    text-align: center;
}

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

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.95;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 5px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

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

.btn-secondary:hover {
    background-color: var(--secondary-color);
    border-color: var(--secondary-color);
    transform: translateY(-2px);
}

/* About Section */
.about {
    padding: 60px 0;
    background-color: var(--light-bg);
    text-align: center;
}

.about h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
    color: var(--dark-text);
}

.about p {
    font-size: 1.1rem;
    color: var(--light-text);
    max-width: 600px;
    margin: 0 auto;
}

/* Topics Section */
.topics {
    padding: 60px 0;
}

.topics h2 {
    font-size: 2rem;
    margin-bottom: 3rem;
    text-align: center;
    color: var(--dark-text);
}

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

.topic-card {
    display: block;
    background-color: white;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    padding: 2rem;
    text-align: center;
    transition: all 0.3s ease;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    text-decoration: none;
    color: inherit;
    cursor: pointer;
}

.topic-card:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    transform: translateY(-5px);
    text-decoration: none;
}

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

.topic-card p {
    color: var(--light-text);
    font-size: 0.95rem;
}

/* Contact Section */
.contact {
    background-color: var(--light-bg);
    padding: 60px 0;
    text-align: center;
}

.contact h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: var(--dark-text);
}

.contact p {
    color: var(--light-text);
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

/* Footer */
footer {
    background-color: var(--dark-text);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        gap: 1rem;
    }

    .hero-content h2 {
        font-size: 1.8rem;
    }

    .hero-content p {
        font-size: 1rem;
    }

    .about h2,
    .topics h2,
    .contact h2 {
        font-size: 1.5rem;
    }

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

    .navbar .container {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .nav-links {
        gap: 0.5rem;
        font-size: 0.9rem;
    }

    .logo {
        font-size: 1.2rem;
    }

    .hero-content h2 {
        font-size: 1.5rem;
    }

    .btn {
        padding: 10px 20px;
        font-size: 0.9rem;
    }
}