:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #06b6d4;
    --accent-color: #10b981;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --background: #ffffff;
    --background-alt: #f9fafb;
    --border-color: #e5e7eb;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --border-radius: 12px;
    --border-radius-lg: 24px;
    --spacing-unit: 1rem;
    --max-width: 1200px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
}

/* Navigation */
.nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: all 0.3s ease;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-text {
    font-size: 1.75rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.3s ease;
}

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

.cta-nav {
    background: var(--primary-color);
    color: white !important;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    transition: all 0.3s ease;
}

.cta-nav:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    padding-top: 80px;
}

.hero-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 1.5rem;
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    line-height: 1.7;
}

.hero-cta {
    display: flex;
    gap: 1rem;
}

.btn-primary, .btn-secondary {
    padding: 1rem 2rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

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

/* Floating Card */
.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.floating-card {
    background: white;
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-lg);
    max-width: 350px;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.card-title {
    font-weight: 600;
    color: var(--text-primary);
}

.card-status {
    background: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

.pk-chart {
    margin-bottom: 1.5rem;
}

.pk-chart svg {
    width: 100%;
    height: auto;
    border-radius: 8px;
    background: #fafafa;
}

.chart-legend {
    display: flex;
    gap: 1rem;
    margin-top: 0.5rem;
    justify-content: center;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.legend-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
}

/* Animation for measurement points */
@keyframes pointPulse {
    0%, 100% { r: 3; opacity: 1; }
    50% { r: 4; opacity: 0.7; }
}

/* Animation for dose arrows */
@keyframes doseFlash {
    0%, 90%, 100% { opacity: 0.7; }
    95% { opacity: 1; }
}

.optimization-result {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: var(--background-alt);
    border-radius: var(--border-radius);
}

.result-label {
    color: var(--text-secondary);
    font-weight: 500;
}

.result-value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--accent-color);
}

/* Sections */
.about, .features, .notify {
    padding: 6rem 0;
}

.stats {
    padding: 4rem 0;
    background: var(--background-alt);
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* About Section */
.about-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 3rem;
}

.about-item {
    text-align: center;
    padding: 2rem;
}

.about-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.about-item h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.about-item p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Features Section */
.features {
    background: var(--background-alt);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2.5rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.feature-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Stats Section */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
}

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

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.stat-label {
    color: var(--text-secondary);
    font-weight: 500;
}

/* Notification Section */
.notify {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
}

.notify-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.notify-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.notify-subtitle {
    font-size: 1.125rem;
    margin-bottom: 2.5rem;
    opacity: 0.9;
}

.notify-form {
    max-width: 500px;
    margin: 0 auto;
}

.form-group {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
}

.form-group input {
    flex: 1;
    padding: 1rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    background: rgba(255, 255, 255, 0.1);
    color: white;
    backdrop-filter: blur(10px);
}

.form-group input::placeholder {
    color: rgba(255, 255, 255, 0.7);
}

.form-group input:focus {
    outline: none;
    background: rgba(255, 255, 255, 0.2);
}

.form-group .btn-primary {
    background: white;
    color: var(--primary-color);
    white-space: nowrap;
}

.form-group .btn-primary:hover {
    background: rgba(255, 255, 255, 0.9);
    transform: translateY(-2px);
}

.form-disclaimer {
    font-size: 0.875rem;
    opacity: 0.8;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 2rem;
}

.footer-tagline {
    color: rgba(255, 255, 255, 0.7);
    margin-top: 0.5rem;
}

.footer-links {
    display: flex;
    gap: 2rem;
    margin-bottom: 1rem;
}

.footer-link {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-link:hover {
    color: white;
}

.footer-social {
    display: flex;
    gap: 1rem;
}

.social-link {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: color 0.3s ease;
}

.social-link:hover {
    color: var(--secondary-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: center;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .about-grid,
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .form-group {
        flex-direction: column;
    }
    
    .footer-content {
        flex-direction: column;
        gap: 2rem;
        text-align: center;
    }
    
    .footer-links {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
    
    .nav-container {
        padding: 1rem;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .floating-card {
        max-width: 280px;
        padding: 1.5rem;
    }
}