:root {
    --primary-green: #004D40;
    --primary-blue: #091E42;
    --accent-blue: #F4F7FB;
    --text-main: #334155;
    --white: #FFFFFF;
}

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

body {
    font-family: 'Inter', sans-serif;
    line-height: 2.0;
    color: var(--text-main);
    font-size: 1.25rem;
}

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

/* Navigation */
.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 8%;
    background: var(--white);
    border-bottom: 1px solid #e2e8f0;
    position: sticky;
    top: 0; z-index: 1000;
}

.logo { font-size: 1.8rem; font-weight: 800; text-decoration: none; color: var(--primary-blue); }
.logo span { color: var(--primary-green); }

.nav-links a, .footer-col a, .footer-legal-links a {
    text-decoration: none;
    color: inherit;
    position: relative;
    padding-bottom: 2px;
    transition: color 0.3s;
}

/* Progressive Underline Effect */
.nav-links a::after, .footer-col a::after, .footer-legal-links a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: var(--primary-green);
    transition: width 0.3s cubic-bezier(0.65, 0, 0.35, 1);
}

.nav-links a:hover::after, .footer-col a:hover::after, .footer-legal-links a:hover::after { width: 100%; }

.nav-links a { margin-left: 2rem; font-weight: 500; color: var(--primary-blue); }

/* Mobile Nav Styles */
.mobile-menu-btn { display: none; cursor: pointer; flex-direction: column; gap: 6px; }
.mobile-menu-btn span { width: 30px; height: 3px; background: var(--primary-blue); border-radius: 2px; }

.mobile-nav {
    display: none;
    position: fixed;
    top: 75px; left: 0; width: 100%; height: calc(100vh - 75px);
    background: var(--white);
    flex-direction: column;
    align-items: center;
    padding-top: 50px;
    z-index: 999;
}

.mobile-nav.active { display: flex; }
.mobile-nav a { font-size: 1.5rem; margin-bottom: 30px; text-decoration: none; color: var(--primary-blue); }

/* Hero & Selector */
.hero { padding: 100px 5%; text-align: center; background: var(--accent-blue); }
.test-selector-box { background: white; padding: 30px; border-radius: 20px; box-shadow: 0 10px 30px rgba(0,0,0,0.05); margin-top: 30px; }
.selector-controls { display: flex; gap: 15px; justify-content: center; flex-wrap: wrap; }
#test-dropdown { padding: 15px; border-radius: 8px; border: 1px solid #ddd; width: 300px; font-size: 1.1rem; }

.btn-primary { background: var(--primary-green); color: white; padding: 15px 30px; border-radius: 8px; border: none; font-weight: 600; cursor: pointer; transition: 0.3s; }
.btn-primary:hover { background: #00332b; }

/* Sections */
.section-padding { padding: 80px 8%; }
.steps-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 30px; }
.step { padding: 30px; border: 1px solid #eee; border-radius: 15px; }
.step-num { font-size: 2.5rem; font-weight: 800; color: var(--primary-green); opacity: 0.3; }

.science-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; margin-top: 40px; }
.science-card { background: white; padding: 25px; border-radius: 12px; border-left: 5px solid var(--primary-green); }

/* Footer */
footer { background: var(--primary-blue); color: #94a3b8; padding: 80px 8% 40px; text-align: left; }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 40px; }
.footer-col h4 { color: white; margin-bottom: 20px; }
.footer-col a { display: block; margin-bottom: 12px; }

.footer-bottom { border-top: 1px solid #1e293b; margin-top: 50px; padding-top: 30px; text-align: center; }
.footer-legal-links { margin: 15px 0; display: flex; justify-content: center; gap: 20px; }
.disclaimer { font-size: 0.85rem; max-width: 800px; margin: 20px auto; opacity: 0.8; }

/* Responsive Adjustments */
@media (max-width: 900px) {
    .nav-links { display: none; }
    .mobile-menu-btn { display: flex; }
    h1 { font-size: 2.2rem; }
    #test-dropdown { width: 100%; }
}