/* Core Styling System & Variables */
:root {
    --bg-dark: #0b0d10;
    --bg-card: rgba(22, 26, 33, 0.7);
    --bg-card-border: rgba(255, 255, 255, 0.07);
    
    --primary: #10b981; /* Success / Healthy Lung */
    --primary-glow: rgba(16, 185, 129, 0.15);
    
    --warning: #f59e0b; /* Moderate / Mild */
    --danger: #ef4444;  /* Severe / Damaged */
    --premium: #f39c12; /* Gold */
    --premium-glow: rgba(243, 156, 18, 0.2);

    --text-primary: #f3f4f6;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;
    
    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Inter', sans-serif;
    
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 32px;
    
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Dynamic lung variables for JS manipulation */
    --lung-color: #10b981;
    --lung-glow: rgba(16, 185, 129, 0.25);
}

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

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-dark);
    color: var(--text-primary);
    font-family: var(--font-body);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* Container */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.text-center {
    text-align: center;
}

/* Typography */
h1, h2, h3, h4 {
    font-family: var(--font-heading);
    font-weight: 700;
    color: #fff;
    line-height: 1.2;
}

.gradient-text {
    background: linear-gradient(135deg, #10b981 0%, #3b82f6 50%, #8b5cf6 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 28px;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 16px;
    text-decoration: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    border: none;
    transition: var(--transition);
}

.btn-sm {
    padding: 8px 16px;
    font-size: 14px;
    border-radius: var(--radius-sm);
}

.btn-lg {
    padding: 18px 36px;
    font-size: 18px;
}

.btn-primary {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: #0b0d10;
    box-shadow: 0 4px 20px rgba(16, 185, 129, 0.35);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(16, 185, 129, 0.5);
    background: linear-gradient(135deg, #34d399 0%, #10b981 100%);
}

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

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--text-secondary);
    transform: translateY(-2px);
}

.btn-premium {
    background: linear-gradient(135deg, var(--premium) 0%, #d35400 100%);
    color: #fff;
    box-shadow: 0 4px 15px var(--premium-glow);
}

.btn-premium:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(243, 156, 18, 0.4);
}

.btn-block {
    display: flex;
    width: 100%;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 100;
    background: rgba(11, 13, 16, 0.8);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--bg-card-border);
    height: 72px;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
}

.logo-icon {
    font-size: 24px;
}

.logo-text {
    font-family: var(--font-heading);
    font-weight: 800;
    font-size: 22px;
    letter-spacing: -0.5px;
}

.logo-accent {
    color: var(--primary);
}

.nav-links {
    display: flex;
    gap: 32px;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: 15px;
    transition: var(--transition);
}

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

.nav-links a.nav-secondary {
    color: var(--text-muted);
}

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

/* Hero Section */
.hero {
    padding-top: 140px;
    padding-bottom: 80px;
    position: relative;
    overflow: hidden;
}

.hero::after {
    content: '';
    position: absolute;
    top: -200px;
    right: -200px;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(16, 185, 129, 0.1) 0%, transparent 70%);
    z-index: -1;
    pointer-events: none;
}

.hero::before {
    content: '';
    position: absolute;
    bottom: -100px;
    left: -100px;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.08) 0%, transparent 70%);
    z-index: -1;
    pointer-events: none;
}

/* Hero Layout Styling */
.hero-grid {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    margin: 0 auto;
}

.badge {
    display: inline-block;
    padding: 6px 12px;
    background: rgba(16, 185, 129, 0.08);
    border: 1.5px solid rgba(16, 185, 129, 0.15);
    color: var(--primary);
    font-size: 13px;
    font-weight: 600;
    border-radius: 50px;
    margin-bottom: 24px;
}

.hero-title {
    font-size: 56px;
    letter-spacing: -1.5px;
    margin-bottom: 20px;
}

.hero-desc {
    font-size: 18px;
    color: var(--text-secondary);
    margin: 0 auto 36px;
    max-width: 580px;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 48px;
}

.hero-stats {
    display: flex;
    gap: 40px;
    justify-content: center;
    border-top: 1px solid var(--bg-card-border);
    padding-top: 32px;
}

.hero-stat-item {
    display: flex;
    flex-direction: column;
}

.stat-num {
    font-family: var(--font-heading);
    font-size: 32px;
    font-weight: 800;
    color: #fff;
}

.stat-label {
    font-size: 13px;
    color: var(--text-muted);
    font-weight: 500;
}

/* Section Titles and Typography */
.section-title {
    font-size: 38px;
    margin-bottom: 12px;
}

.section-subtitle {
    color: var(--text-secondary);
    max-width: 650px;
    margin: 0 auto 48px;
    font-size: 16px;
}

/* Features Section */
.features {
    padding: 80px 0;
    border-top: 1px solid var(--bg-card-border);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--bg-card-border);
    border-radius: var(--radius-md);
    padding: 32px;
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-4px);
    border-color: rgba(255,255,255,0.12);
}

.feature-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.feat-badge-icon {
    font-size: 24px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    background: rgba(255, 255, 255, 0.03);
    border-radius: 12px;
}

.feature-card h3 {
    font-size: 18px;
}

.feature-text {
    font-size: 14px;
    color: var(--text-secondary);
}

/* Download CTA Section */
.download-cta {
    padding: 100px 0;
    background: radial-gradient(circle at center, rgba(16, 185, 129, 0.08) 0%, transparent 60%);
    border-top: 1px solid var(--bg-card-border);
}

.cta-title {
    font-size: 42px;
    margin-bottom: 16px;
}

.cta-desc {
    font-size: 18px;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 36px;
}

.cta-actions {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 24px;
}

.btn-icon {
    margin-right: 8px;
    font-size: 20px;
}

.cta-requirement {
    font-size: 13px;
    color: var(--text-muted);
}

/* Footer */
.footer {
    border-top: 1px solid var(--bg-card-border);
    padding: 60px 0 30px;
    background: #08090b;
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 40px;
}

.footer-brand {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-logo {
    font-family: var(--font-heading);
    font-size: 20px;
    font-weight: 800;
}

.footer-tag {
    font-size: 14px;
    color: var(--text-muted);
}

.footer h4 {
    font-size: 14px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.footer-links, .footer-legal {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.footer-links a, .footer-legal a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
    transition: var(--transition);
}

.footer-links a:hover, .footer-legal a:hover {
    color: var(--text-primary);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.04);
    padding-top: 24px;
    font-size: 12px;
    color: var(--text-muted);
}

/* Responsive adjustments */
@media (max-width: 991px) {
    .hero-grid {
        grid-template-columns: 1fr;
        gap: 48px;
        text-align: center;
    }
    
    .hero-content {
        display: flex;
        flex-direction: column;
        align-items: center;
    }
    
    .hero-desc {
        margin-left: auto;
        margin-right: auto;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .features-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 767px) {
    .navbar {
        height: 64px;
    }
    
    .nav-links {
        display: none; /* simple hidden on mobile */
    }
    
    .hero-title {
        font-size: 40px;
    }
    
    .hero-desc {
        font-size: 16px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .cta-actions {
        flex-direction: column;
        align-items: center;
        gap: 12px;
    }
    
    .cta-actions .btn {
        width: 100%;
        max-width: 320px;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }
}