:root {
    --bg-dark: #0a0c10;
    --accent-blue: #4facfe;
    --accent-glow: rgba(79, 172, 254, 0.4);
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --text-primary: #f0f4f8;
    --text-secondary: #a0aec0;
    --transition-smooth: all 0.6s cubic-bezier(0.16, 1, 0.3, 1);
    --transition-bounce: all 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
    scroll-behavior: smooth;
}

h1, h2, h3 {
    font-family: 'Outfit', sans-serif;
    font-weight: 700;
}

/* Glass Navigation */
.glass-nav {
    position: fixed;
    top: 0;
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 5%;
    background: rgba(10, 12, 16, 0.7);
    backdrop-filter: blur(15px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 1000;
}

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

.nav-logo-img {
    height: 55px;
    width: auto;
    display: block;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.5);
    border: none;
    clip-path: inset(6px round 10px);
}

#language-switcher {
    background: var(--glass-bg);
    color: #fff;
    border: 1px solid var(--glass-border);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    outline: none;
    cursor: pointer;
    font-family: inherit;
    transition: var(--transition-smooth);
}

#language-switcher:hover {
    border-color: var(--accent-blue);
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: url('media/hero_bg.png') center/cover no-repeat;
    position: relative;
    padding: 0 5%;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, rgba(10, 12, 16, 0.4) 0%, rgba(10, 12, 16, 0.95) 100%), radial-gradient(circle at center, transparent 30%, var(--bg-dark) 100%);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
}

.hero h1 {
    font-size: clamp(2.5rem, 8vw, 5rem);
    margin-bottom: 1.5rem;
    background: linear-gradient(to bottom, #fff, #a0aec0);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    color: transparent;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
}

.btn-primary {
    display: inline-block;
    padding: 1rem 2.5rem;
    background: linear-gradient(135deg, var(--accent-blue), #00f2fe);
    color: #000;
    text-decoration: none;
    border-radius: 50px;
    font-weight: 600;
    box-shadow: 0 10px 20px rgba(79, 172, 254, 0.3);
    transition: var(--transition-smooth);
}

.btn-primary:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px var(--accent-glow);
}

/* Why Holter Section */
.why-holter {
    padding: 6rem 5%;
    text-align: center;
    background: linear-gradient(to bottom, var(--bg-dark), rgba(255, 255, 255, 0.02));
}

.why-holter h2 {
    font-size: clamp(2rem, 5vw, 3rem);
    margin-bottom: 4rem;
    color: var(--text-primary);
}

.use-cases {
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.use-case-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 3rem 2rem;
    max-width: 350px;
    flex: 1;
    min-width: 250px;
    transition: var(--transition-smooth);
    will-change: transform, opacity;
}

.use-case-card:hover {
    transform: translateY(-10px);
    background: rgba(255, 255, 255, 0.08);
    border-color: var(--accent-blue);
    box-shadow: 0 15px 30px rgba(79, 172, 254, 0.15);
}

.use-case-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 80px;
    height: 80px;
    margin: 0 auto 1.5rem auto;
    background: rgba(79, 172, 254, 0.08);
    border-radius: 50%;
    color: var(--accent-blue);
    transition: var(--transition-smooth);
}

.use-case-icon svg {
    width: 40px;
    height: 40px;
}

.use-case-card:hover .use-case-icon {
    background: rgba(79, 172, 254, 0.18);
    box-shadow: 0 0 25px rgba(79, 172, 254, 0.2);
}

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

.use-case-card p {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.6;
}

/* Split Features (Strava-inspired) */
.features-split {
    padding: 5rem 5%;
}

.split-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 4rem;
    margin-bottom: 8rem;
    will-change: transform, opacity;
}

.split-row.reverse {
    flex-direction: row-reverse;
}

.split-text {
    flex: 1;
}

.split-text h2 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.split-text p {
    font-size: 1.25rem;
    color: var(--text-secondary);
}

.split-image {
    flex: 1;
    position: relative;
    border-radius: 24px;
    overflow: hidden;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
}

.split-image img {
    width: 100%;
    height: auto;
    display: block;
    transition: var(--transition-smooth);
}

.split-row:hover .split-image img {
    transform: scale(1.03);
}

.placeholder-graphic {
    width: 100%;
    padding: 40% 0;
    background: linear-gradient(135deg, rgba(255,255,255,0.05), rgba(79, 172, 254, 0.1));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: var(--accent-blue);
    font-weight: 600;
}

/* Phone Mockup for Screenshots */
.phone-mockup {
    width: 100%;
    max-width: 280px;
    margin: 0 auto;
    background: #111;
    border-radius: 40px;
    padding: 10px;
    box-shadow: 0 0 0 2px #333, 0 30px 60px rgba(0,0,0,0.6), inset 0 0 0 2px #555;
    position: relative;
    aspect-ratio: 9/19.5;
}

.phone-mockup::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 110px;
    height: 25px;
    background: #111;
    border-bottom-left-radius: 16px;
    border-bottom-right-radius: 16px;
    z-index: 2;
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: var(--bg-dark);
    border-radius: 30px;
    overflow: hidden;
    position: relative;
}

.screenshot-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    font-weight: 600;
    background: linear-gradient(135deg, rgba(79, 172, 254, 0.1), rgba(0, 0, 0, 0.5));
}

/* App Store Banner */
.app-banner {
    padding: 6rem 5%;
    text-align: center;
    background: linear-gradient(to bottom, transparent, rgba(0,0,0,0.5));
    border-top: 1px solid var(--glass-border);
}

.app-banner h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
}

.btn-app-store {
    display: inline-flex;
    align-items: center;
    background: #000;
    color: #fff;
    padding: 0.8rem 1.5rem;
    border-radius: 12px;
    border: 1px solid #333;
    text-decoration: none;
    transition: var(--transition-bounce);
}

.btn-app-store:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(255, 255, 255, 0.1);
}

.btn-app-store svg {
    width: 30px;
    height: 30px;
    margin-right: 12px;
}

.btn-app-store .btn-text {
    text-align: left;
}

.btn-app-store .small {
    display: block;
    font-size: 0.65rem;
    line-height: 1;
    text-transform: uppercase;
    color: #ccc;
    letter-spacing: 0.5px;
}

.btn-app-store .large {
    display: block;
    font-size: 1.25rem;
    line-height: 1;
    font-weight: 600;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

/* Disclaimer Section */
.disclaimer {
    padding: 5rem 5%;
    background: rgba(255, 255, 255, 0.02);
}

.disclaimer-content {
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
    border-left: 4px solid var(--accent-blue);
    padding: 2rem;
    background: var(--glass-bg);
    border-radius: 0 20px 20px 0;
}

.disclaimer h2 {
    margin-bottom: 1rem;
    font-size: 1.5rem;
    color: var(--accent-blue);
}

.disclaimer p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Footer */
footer {
    padding: 3rem 5%;
    text-align: center;
    border-top: 1px solid var(--glass-border);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 900px) {
    .glass-nav {
        padding: 1rem 5%;
    }
    .hero h1 {
        font-size: 3rem;
    }
    .split-row, .split-row.reverse {
        flex-direction: column;
        text-align: center;
        gap: 2rem;
        margin-bottom: 5rem;
    }
}