:root {
    --primary-color: #0f172a; /* Slate 900 */
    --secondary-color: #334155; /* Slate 700 */
    --accent-color: #0ea5e9; /* Sky 500 */
    --background-color: #ffffff;
    --light-bg: #f8fafc; /* Slate 50 */
    --text-color: #1e293b; /* Slate 800 */
    --text-light: #64748b; /* Slate 500 */
    --font-family: 'Inter', sans-serif;
    --transition: 0.3s ease;
}

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

body {
    font-family: var(--font-family);
    color: var(--text-color);
    line-height: 1.6;
    background-color: var(--background-color);
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #e2e8f0;
    z-index: 1000;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    text-decoration: none;
    letter-spacing: -0.02em;
}

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

.nav-list a {
    text-decoration: none;
    color: var(--secondary-color);
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition);
}

.nav-list a:hover {
    color: var(--accent-color);
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(to bottom, #f0f9ff, #ffffff);
    padding-top: 80px;
}

.hero-title {
    font-size: 4rem;
    font-weight: 300;
    color: var(--primary-color);
    margin-bottom: 1rem;
    letter-spacing: -0.03em;
}

.hero-slogan {
    font-size: 1.25rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto 3rem;
    font-weight: 400;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.8rem 2rem;
    background-color: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 4px;
    font-weight: 500;
    transition: var(--transition);
}

.btn:hover {
    background-color: var(--secondary-color);
    transform: translateY(-1px);
}

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
}

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

/* Sections */
.section {
    padding: 6rem 0;
}

.section-title {
    font-size: 2rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 3rem;
    text-align: center;
    letter-spacing: -0.02em;
}

.section-content {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1.1rem;
    color: var(--secondary-color);
}

.bg-light {
    background-color: var(--light-bg);
}

/* Grid for Methodology */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.card {
    background: white;
    padding: 2.5rem;
    border-radius: 8px;
    border: 1px solid #e2e8f0;
    transition: var(--transition);
}

.card:hover {
    box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.05);
    border-color: #cbd5e1;
}

.card h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
    font-weight: 600;
}

/* Utility */
.text-center {
    text-align: center;
}

/* Footer */
.footer {
    padding: 2rem 0;
    background-color: var(--primary-color);
    color: white;
    text-decoration: none;
    text-align: center;
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .nav-list {
        display: none; /* Mobile menu implementation left for future enhancement if needed */
    }
}