/* ==========================================================================
   TubTest Website Styles
   Apple.com-inspired cinematic design
   ========================================================================== */

/* ==========================================================================
   1. CSS Variables
   ========================================================================== */
:root {
    /* Colors */
    --color-primary: #164c53;
    --color-primary-dark: #0d2f33;
    --color-secondary: #7FB4B9;
    --color-accent: #43929b;
    --color-text-dark: #1d1d1f;
    --color-text-light: #86868b;
    --color-text-white: #f5f5f7;
    --color-bg-light: #fbfbfd;
    --color-bg-dark: #0a1a1d;
    --color-bg-cream: #F5F0E6;
    --color-bg-teal: #164c53;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display",
                   "SF Pro Text", "Helvetica Neue", Helvetica, Arial, sans-serif;
    --font-size-hero: clamp(2.5rem, 7vw, 5rem);
    --font-size-section: clamp(2rem, 5vw, 3.5rem);
    --font-size-subsection: clamp(1.5rem, 3vw, 2rem);
    --font-size-body: 1.125rem;
    --font-size-body-large: 1.25rem;
    --font-size-small: 0.875rem;
    --font-size-label: 0.75rem;

    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    /* Spacing */
    --section-padding: clamp(5rem, 10vw, 10rem);
    --section-padding-small: clamp(3rem, 6vw, 6rem);
    --container-max: 1200px;
    --container-padding: 1.5rem;

    /* Animation */
    --transition-fast: 0.2s ease;
    --transition-medium: 0.4s ease;
    --transition-slow: 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    --transition-bounce: 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);

    /* Shadows */
    --shadow-small: 0 4px 20px rgba(0, 0, 0, 0.08);
    --shadow-medium: 0 20px 40px rgba(0, 0, 0, 0.12);
    --shadow-large: 0 30px 60px rgba(0, 0, 0, 0.2);
    --shadow-phone: 0 50px 100px rgba(0, 0, 0, 0.3);

    /* Border Radius */
    --radius-small: 12px;
    --radius-medium: 20px;
    --radius-large: 30px;
    --radius-xl: 44px;
    --radius-pill: 980px;
}

/* ==========================================================================
   2. Reset & Base
   ========================================================================== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-body);
    font-weight: var(--font-weight-regular);
    line-height: 1.6;
    color: var(--color-text-dark);
    background-color: var(--color-bg-light);
    overflow-x: hidden;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary);
}

/* ==========================================================================
   3. Typography
   ========================================================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-weight-semibold);
    line-height: 1.1;
    letter-spacing: -0.02em;
}

.hero-title {
    font-size: var(--font-size-hero);
    font-weight: var(--font-weight-bold);
    letter-spacing: -0.03em;
}

.section-title {
    font-size: var(--font-size-section);
    font-weight: var(--font-weight-semibold);
    margin-bottom: 1rem;
}

.section-subtitle {
    font-size: var(--font-size-body-large);
    color: var(--color-text-light);
    max-width: 600px;
}

.label {
    font-size: var(--font-size-label);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-secondary);
    margin-bottom: 0.75rem;
    display: block;
}

.text-center { text-align: center; }
.text-white { color: var(--color-text-white); }
.text-light { color: var(--color-text-light); }

/* ==========================================================================
   4. Layout & Container
   ========================================================================== */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.container-narrow {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

section {
    padding: var(--section-padding) 0;
    position: relative;
    overflow: hidden;
}

.section-small {
    padding: var(--section-padding-small) 0;
}

/* ==========================================================================
   5. Navigation
   ========================================================================== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 1rem 0;
    transition: all var(--transition-medium);
}

.nav.scrolled {
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    box-shadow: 0 1px 0 rgba(0, 0, 0, 0.1);
}

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

.nav-logo {
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-white);
    transition: color var(--transition-fast);
}

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

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

.nav-link {
    color: rgba(255, 255, 255, 0.8);
    font-size: var(--font-size-small);
    font-weight: var(--font-weight-medium);
    transition: color var(--transition-fast);
    position: relative;
}

.nav.scrolled .nav-link {
    color: var(--color-text-dark);
}

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

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--color-secondary);
    transform: scaleX(0);
    transition: transform var(--transition-fast);
}

.nav-link:hover::after {
    transform: scaleX(1);
}

/* Mobile nav toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-text-white);
    transition: all var(--transition-fast);
}

.nav.scrolled .nav-toggle span {
    background: var(--color-text-dark);
}

/* ==========================================================================
   6. Hero Section
   ========================================================================== */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 8rem 1.5rem 6rem;
    background: linear-gradient(180deg, var(--color-bg-dark) 0%, var(--color-primary) 50%, var(--color-accent) 100%);
    position: relative;
    overflow: hidden;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 900px;
}

.hero-icon {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-medium);
    margin: 0 auto 2rem;
    box-shadow: var(--shadow-medium);
    animation: pulse-glow 3s ease-in-out infinite;
}

.hero-title {
    color: var(--color-text-white);
    margin-bottom: 1.5rem;
}

.hero-subtitle {
    font-size: var(--font-size-body-large);
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 1.5rem;
}

.hero-note {
    font-size: var(--font-size-small);
    color: rgba(255, 255, 255, 0.6);
}

/* Hero Phone Mockup */
.hero-phone {
    margin-top: 4rem;
    position: relative;
    z-index: 2;
}

.phone-mockup {
    position: relative;
    width: 280px;
    margin: 0 auto;
    animation: float-phone 6s ease-in-out infinite;
}

.phone-frame {
    background: #1a1a1a;
    border-radius: 44px;
    padding: 12px;
    box-shadow: var(--shadow-phone);
    position: relative;
}

.phone-screen {
    border-radius: 34px;
    overflow: hidden;
    background: #000;
}

.phone-screen img {
    width: 100%;
    display: block;
}

/* Subtle glow on dark backgrounds for visibility */
.bg-dark .phone-frame {
    box-shadow: var(--shadow-phone), 0 0 80px 20px rgba(127, 180, 185, 0.25);
}

/* Hero Bubbles */
.hero-bubbles {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
    overflow: hidden;
}

.bubble {
    position: absolute;
    border-radius: 50%;
    background: rgba(127, 180, 185, 0.15);
    animation: float-bubble 8s ease-in-out infinite;
}

.bubble:nth-child(1) { width: 80px; height: 80px; left: 10%; bottom: -80px; animation-delay: 0s; animation-duration: 10s; }
.bubble:nth-child(2) { width: 40px; height: 40px; left: 25%; bottom: -40px; animation-delay: 2s; animation-duration: 8s; }
.bubble:nth-child(3) { width: 60px; height: 60px; left: 45%; bottom: -60px; animation-delay: 1s; animation-duration: 12s; }
.bubble:nth-child(4) { width: 30px; height: 30px; left: 65%; bottom: -30px; animation-delay: 3s; animation-duration: 9s; }
.bubble:nth-child(5) { width: 50px; height: 50px; left: 80%; bottom: -50px; animation-delay: 0.5s; animation-duration: 11s; }
.bubble:nth-child(6) { width: 70px; height: 70px; left: 90%; bottom: -70px; animation-delay: 2.5s; animation-duration: 10s; }

/* ==========================================================================
   7. Buttons
   ========================================================================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    border-radius: var(--radius-pill);
    font-size: var(--font-size-body);
    font-weight: var(--font-weight-medium);
    text-decoration: none;
    transition: all var(--transition-medium);
    cursor: pointer;
    border: none;
}

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

.btn-primary:hover {
    transform: scale(1.05);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    color: var(--color-primary);
}

.btn-secondary {
    background: transparent;
    color: var(--color-text-white);
    border: 2px solid rgba(255, 255, 255, 0.3);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.5);
    color: var(--color-text-white);
}

.btn-dark {
    background: var(--color-primary);
    color: var(--color-text-white);
}

.btn-dark:hover {
    background: var(--color-primary-dark);
    transform: scale(1.05);
    box-shadow: 0 10px 30px rgba(22, 76, 83, 0.3);
    color: var(--color-text-white);
}

.btn-icon {
    width: 20px;
    height: 20px;
}

/* App Store Button Style */
.btn-appstore {
    background: #000;
    color: #fff;
    padding: 0.75rem 1.5rem;
    gap: 0.75rem;
}

.btn-appstore:hover {
    background: #333;
    color: #fff;
    transform: scale(1.05);
}

.btn-appstore svg {
    width: 28px;
    height: 28px;
}

.btn-appstore-text {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    line-height: 1.2;
}

.btn-appstore-text small {
    font-size: 0.65rem;
    font-weight: var(--font-weight-regular);
}

.btn-appstore-text span {
    font-size: 1.1rem;
    font-weight: var(--font-weight-semibold);
}

.btn-playstore {
    background: #000;
    color: #fff;
    padding: 0.75rem 1.5rem;
    gap: 0.75rem;
}

.btn-playstore:hover {
    background: #333;
    color: #fff;
    transform: scale(1.05);
}

.btn-playstore svg {
    width: 28px;
    height: 28px;
}

/* ==========================================================================
   8. Feature Sections
   ========================================================================== */
.feature-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.feature-section.reverse {
    direction: rtl;
}

.feature-section.reverse > * {
    direction: ltr;
}

.feature-content {
    max-width: 500px;
}

.feature-content .label {
    color: var(--color-accent);
}

.feature-content .section-title {
    margin-bottom: 1.5rem;
}

.feature-content .section-subtitle {
    margin-bottom: 2rem;
}

.feature-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.feature-list li {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    font-size: var(--font-size-body);
}

.feature-list li svg {
    flex-shrink: 0;
    width: 24px;
    height: 24px;
    color: var(--color-secondary);
    margin-top: 2px;
}

.feature-phone {
    display: flex;
    justify-content: center;
}

/* Background variants */
.bg-dark {
    background: var(--color-bg-dark);
    color: var(--color-text-white);
}

.bg-dark .section-subtitle,
.bg-dark .feature-list li {
    color: rgba(255, 255, 255, 0.7);
}

.bg-dark .label {
    color: var(--color-secondary);
}

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

.bg-teal {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    color: var(--color-text-white);
}

.bg-teal .section-subtitle {
    color: rgba(255, 255, 255, 0.8);
}

/* ==========================================================================
   9. How It Works
   ========================================================================== */
.steps-container {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-top: 4rem;
}

.step-card {
    text-align: center;
    padding: 2rem;
    position: relative;
}

.step-number {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: var(--color-primary);
    color: var(--color-text-white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    margin: 0 auto 1.5rem;
    position: relative;
    z-index: 1;
}

.step-card:not(:last-child)::after {
    content: '';
    position: absolute;
    top: 50px;
    left: calc(50% + 40px);
    width: calc(100% - 80px);
    height: 2px;
    background: linear-gradient(90deg, var(--color-secondary), transparent);
    z-index: 0;
}

.step-title {
    font-size: var(--font-size-subsection);
    margin-bottom: 0.75rem;
}

.step-description {
    color: var(--color-text-light);
    font-size: var(--font-size-body);
}

/* ==========================================================================
   10. Test Kits Grid
   ========================================================================== */
.kits-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
    margin-top: 3rem;
}

.kit-card {
    background: #fff;
    border-radius: var(--radius-medium);
    padding: 1.5rem;
    text-align: center;
    box-shadow: var(--shadow-small);
    transition: all var(--transition-medium);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.kit-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-medium);
}

.kit-icon {
    width: 48px;
    height: 48px;
    margin: 0 auto 1rem;
    background: var(--color-bg-cream);
    border-radius: var(--radius-small);
    display: flex;
    align-items: center;
    justify-content: center;
}

.kit-icon svg {
    width: 28px;
    height: 28px;
    color: var(--color-primary);
}

.kit-name {
    font-size: 1rem;
    font-weight: var(--font-weight-semibold);
    margin-bottom: 0.5rem;
    color: var(--color-text-dark);
}

.kit-description {
    font-size: var(--font-size-small);
    color: var(--color-text-light);
    line-height: 1.4;
}

/* ==========================================================================
   11. Features Grid
   ========================================================================== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-top: 3rem;
}

.feature-card {
    background: #fff;
    border-radius: var(--radius-medium);
    padding: 2rem;
    box-shadow: var(--shadow-small);
    transition: all var(--transition-medium);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-medium);
}

.feature-card-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, var(--color-secondary), var(--color-accent));
    border-radius: var(--radius-small);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.25rem;
}

.feature-card-icon svg {
    width: 28px;
    height: 28px;
    color: #fff;
}

.feature-card-title {
    font-size: 1.125rem;
    font-weight: var(--font-weight-semibold);
    margin-bottom: 0.5rem;
}

.feature-card-description {
    font-size: var(--font-size-body);
    color: var(--color-text-light);
    line-height: 1.5;
}

/* ==========================================================================
   12. Testimonials
   ========================================================================== */
.testimonials-container {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-top: 3rem;
}

.testimonial-card {
    background: #fff;
    border-radius: var(--radius-medium);
    padding: 2rem;
    box-shadow: var(--shadow-small);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.testimonial-stars {
    display: flex;
    gap: 0.25rem;
    margin-bottom: 1rem;
}

.testimonial-stars svg {
    width: 18px;
    height: 18px;
    color: #FFB800;
    fill: #FFB800;
}

.testimonial-text {
    font-size: var(--font-size-body);
    color: var(--color-text-dark);
    margin-bottom: 1rem;
    font-style: italic;
    line-height: 1.6;
}

.testimonial-author {
    font-size: var(--font-size-small);
    color: var(--color-text-light);
    font-weight: var(--font-weight-medium);
}

/* ==========================================================================
   13. CTA Section
   ========================================================================== */
.cta-section {
    text-align: center;
    padding: var(--section-padding) var(--container-padding);
}

.cta-icon {
    width: 100px;
    height: 100px;
    border-radius: var(--radius-large);
    margin: 0 auto 2rem;
    box-shadow: var(--shadow-large);
    animation: pulse-glow 3s ease-in-out infinite;
}

.cta-title {
    font-size: var(--font-size-section);
    margin-bottom: 1rem;
}

.cta-subtitle {
    font-size: var(--font-size-body-large);
    margin-bottom: 2.5rem;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

/* ==========================================================================
   14. Footer
   ========================================================================== */
.footer {
    background: var(--color-bg-dark);
    color: var(--color-text-white);
    padding: 4rem 0 2rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 3rem;
}

.footer-brand {
    max-width: 300px;
}

.footer-logo {
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-white);
    margin-bottom: 0.75rem;
}

.footer-tagline {
    color: rgba(255, 255, 255, 0.6);
    font-size: var(--font-size-body);
}

.footer-links {
    display: flex;
    gap: 3rem;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    font-size: var(--font-size-body);
    transition: color var(--transition-fast);
}

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

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

.footer-copyright {
    color: rgba(255, 255, 255, 0.4);
    font-size: var(--font-size-small);
}

/* ==========================================================================
   15. Animations
   ========================================================================== */
@keyframes float-phone {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

@keyframes float-bubble {
    0% {
        transform: translateY(0) scale(1);
        opacity: 0.6;
    }
    50% {
        opacity: 0.8;
    }
    100% {
        transform: translateY(-100vh) scale(1.2);
        opacity: 0;
    }
}

@keyframes pulse-glow {
    0%, 100% { box-shadow: 0 0 30px rgba(127, 180, 185, 0.4); }
    50% { box-shadow: 0 0 60px rgba(127, 180, 185, 0.7); }
}

@keyframes fade-up {
    from {
        opacity: 0;
        transform: translateY(40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Scroll-triggered animation classes */
.animate {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.animate.fade-left {
    transform: translateX(60px);
}

.animate.fade-right {
    transform: translateX(-60px);
}

.animate.fade-scale {
    transform: scale(0.95);
}

.animate.visible {
    opacity: 1;
    transform: translateY(0) translateX(0) scale(1);
}

/* Stagger children */
.stagger-children .animate:nth-child(1) { transition-delay: 0s; }
.stagger-children .animate:nth-child(2) { transition-delay: 0.1s; }
.stagger-children .animate:nth-child(3) { transition-delay: 0.2s; }
.stagger-children .animate:nth-child(4) { transition-delay: 0.3s; }
.stagger-children .animate:nth-child(5) { transition-delay: 0.4s; }
.stagger-children .animate:nth-child(6) { transition-delay: 0.5s; }
.stagger-children .animate:nth-child(7) { transition-delay: 0.6s; }
.stagger-children .animate:nth-child(8) { transition-delay: 0.7s; }

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    .animate {
        opacity: 1;
        transform: none;
    }
}

/* ==========================================================================
   16. Shop Page Styles
   ========================================================================== */
.shop-hero {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    padding: 8rem 0 4rem;
    text-align: center;
}

.shop-hero .section-title {
    color: var(--color-text-white);
}

.shop-hero .section-subtitle {
    color: rgba(255, 255, 255, 0.8);
    margin: 0 auto;
}

.affiliate-notice {
    background: var(--color-bg-cream);
    padding: 1rem 1.5rem;
    border-radius: var(--radius-small);
    font-size: var(--font-size-small);
    color: var(--color-text-light);
    text-align: center;
    max-width: 700px;
    margin: 2rem auto;
}

.product-category {
    margin-bottom: 4rem;
}

.category-title {
    font-size: var(--font-size-subsection);
    margin-bottom: 1.5rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--color-secondary);
    display: inline-block;
}

.products-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.product-card {
    background: #fff;
    border-radius: var(--radius-medium);
    padding: 1.5rem;
    box-shadow: var(--shadow-small);
    transition: all var(--transition-medium);
    border: 1px solid rgba(0, 0, 0, 0.05);
    display: flex;
    flex-direction: column;
}

.product-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-medium);
}

.product-card.featured {
    grid-column: span 2;
    flex-direction: row;
    gap: 2rem;
    align-items: center;
}

.product-name {
    font-size: 1.125rem;
    font-weight: var(--font-weight-semibold);
    margin-bottom: 0.5rem;
    color: var(--color-text-dark);
}

.product-description {
    font-size: var(--font-size-body);
    color: var(--color-text-light);
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.product-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--color-accent);
    font-weight: var(--font-weight-medium);
    font-size: var(--font-size-body);
}

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

.product-link svg {
    width: 18px;
    height: 18px;
    transition: transform var(--transition-fast);
}

.product-link:hover svg {
    transform: translateX(4px);
}

/* ==========================================================================
   17. Privacy Page Styles
   ========================================================================== */
.privacy-hero {
    background: var(--color-bg-dark);
    padding: 8rem 0 3rem;
    text-align: center;
}

.privacy-hero .section-title {
    color: var(--color-text-white);
}

.privacy-content {
    padding: var(--section-padding-small) 0;
}

.privacy-content h2 {
    font-size: var(--font-size-subsection);
    margin: 2rem 0 1rem;
    color: var(--color-primary);
}

.privacy-content p {
    margin-bottom: 1rem;
    color: var(--color-text-dark);
    line-height: 1.7;
}

.privacy-content ul {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
}

.privacy-content li {
    margin-bottom: 0.5rem;
    color: var(--color-text-dark);
}

.privacy-highlight {
    background: var(--color-bg-cream);
    padding: 1.5rem;
    border-radius: var(--radius-small);
    margin-bottom: 2rem;
}

.privacy-highlight p {
    margin: 0;
    font-weight: var(--font-weight-medium);
}

/* ==========================================================================
   18. Responsive Design
   ========================================================================== */
@media (max-width: 1024px) {
    .feature-section {
        grid-template-columns: 1fr;
        gap: 3rem;
        text-align: center;
    }

    .feature-section.reverse {
        direction: ltr;
    }

    .feature-content {
        max-width: 100%;
        margin: 0 auto;
    }

    .feature-list {
        align-items: center;
    }

    .kits-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .testimonials-container {
        grid-template-columns: 1fr;
        max-width: 500px;
        margin-left: auto;
        margin-right: auto;
    }

    .product-card.featured {
        grid-column: span 1;
        flex-direction: column;
    }
}

@media (max-width: 768px) {
    :root {
        --section-padding: clamp(3rem, 8vw, 6rem);
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 1.5rem;
        gap: 0;
        box-shadow: var(--shadow-medium);
    }

    .nav-links.active {
        display: flex;
    }

    .nav-links li {
        border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    }

    .nav-links li:last-child {
        border-bottom: none;
    }

    .nav-link {
        display: block;
        padding: 1rem 0;
        color: var(--color-text-dark);
    }

    .nav-toggle {
        display: flex;
    }

    .hero {
        padding: 7rem 1.5rem 4rem;
        min-height: auto;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .phone-mockup {
        width: 240px;
    }

    .steps-container {
        grid-template-columns: 1fr;
        gap: 2.5rem;
    }

    .step-card::after {
        display: none;
    }

    .kits-grid {
        grid-template-columns: 1fr 1fr;
        gap: 1rem;
    }

    .kit-card {
        padding: 1rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .footer-content {
        flex-direction: column;
        gap: 2rem;
        text-align: center;
    }

    .footer-links {
        flex-direction: column;
        gap: 1rem;
    }
}

@media (max-width: 480px) {
    .kits-grid {
        grid-template-columns: 1fr;
    }

    .phone-mockup {
        width: 220px;
    }

    .btn {
        padding: 0.875rem 1.5rem;
        font-size: var(--font-size-small);
    }
}

/* ==========================================================================
   19. Demo Modal Styles
   ========================================================================== */

/* Demo Button */
.btn-demo {
    background: transparent;
    color: var(--color-text-white);
    border: 2px solid var(--color-secondary);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-demo:hover {
    background: var(--color-secondary);
    color: var(--color-primary-dark);
    transform: scale(1.05);
}

/* Modal Overlay */
.demo-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.demo-modal.active {
    opacity: 1;
    visibility: visible;
}

.demo-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

/* Modal Container */
.demo-container {
    position: relative;
    background: linear-gradient(180deg, var(--color-bg-dark) 0%, var(--color-primary-dark) 100%);
    border-radius: var(--radius-large);
    max-width: 480px;
    width: 100%;
    max-height: 90vh;
    overflow: hidden;
    box-shadow: 0 25px 80px rgba(0, 0, 0, 0.5), 0 0 100px rgba(127, 180, 185, 0.15);
    transform: scale(0.9) translateY(20px);
    transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    display: flex;
    flex-direction: column;
}

.demo-modal.active .demo-container {
    transform: scale(1) translateY(0);
}

/* Close Button */
.demo-close {
    position: absolute;
    top: 1rem;
    right: 1rem;
    width: 40px;
    height: 40px;
    border: none;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    z-index: 10;
}

.demo-close svg {
    width: 20px;
    height: 20px;
    color: rgba(255, 255, 255, 0.7);
}

.demo-close:hover {
    background: rgba(255, 255, 255, 0.2);
}

.demo-close:hover svg {
    color: #fff;
}

/* Demo Header */
.demo-header {
    padding: 2rem 2rem 1rem;
    text-align: center;
}

.demo-label {
    font-size: var(--font-size-label);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-secondary);
    margin-bottom: 0.5rem;
    display: block;
}

.demo-title {
    font-size: 1.75rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-white);
    margin-bottom: 1rem;
}

.demo-progress {
    height: 4px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 2px;
    overflow: hidden;
    margin-bottom: 0.75rem;
}

.demo-progress-bar {
    height: 100%;
    width: 25%;
    background: linear-gradient(90deg, var(--color-secondary), var(--color-accent));
    border-radius: 2px;
    transition: width 0.4s ease;
}

.demo-step-indicator {
    font-size: var(--font-size-small);
    color: rgba(255, 255, 255, 0.6);
}

/* Demo Content */
.demo-content {
    flex: 1;
    overflow-y: auto;
    padding: 1rem 2rem 2rem;
    min-height: 400px;
}

.demo-step {
    display: none;
    animation: fadeIn 0.4s ease;
}

.demo-step.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateX(20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Test Tube Visualization */
.demo-tube-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 2rem;
    position: relative;
    min-height: 200px;
}

.demo-tube {
    width: 60px;
    height: 180px;
    position: relative;
    margin-bottom: 1rem;
}

.demo-tube-frame {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 0 0 30px 30px;
    border-top: none;
    background: linear-gradient(90deg,
        rgba(255, 255, 255, 0.1) 0%,
        rgba(255, 255, 255, 0.05) 50%,
        rgba(255, 255, 255, 0.1) 100%);
}

.demo-tube-frame::before {
    content: '';
    position: absolute;
    top: -8px;
    left: -8px;
    right: -8px;
    height: 16px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 4px;
}

.demo-tube-liquid {
    position: absolute;
    bottom: 3px;
    left: 3px;
    right: 3px;
    border-radius: 0 0 27px 27px;
    transition: height 0.8s ease, background 0.8s ease;
}

.demo-tube-fill-line {
    position: absolute;
    top: 30%;
    left: -50px;
    right: -50px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.demo-tube-fill-line::before {
    content: '';
    flex: 1;
    height: 1px;
    background: rgba(255, 255, 255, 0.3);
    border-style: dashed;
}

.demo-tube-fill-line::after {
    content: '';
    flex: 1;
    height: 1px;
    background: rgba(255, 255, 255, 0.3);
    border-style: dashed;
}

.demo-tube-fill-line span {
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.7);
    white-space: nowrap;
}

/* Animated drop */
.demo-falling-drop {
    position: absolute;
    width: 8px;
    height: 12px;
    background: var(--color-secondary);
    border-radius: 50% 50% 50% 50% / 30% 30% 70% 70%;
    left: calc(50% - 4px);
    top: 20px;
    opacity: 0;
    pointer-events: none;
}

.demo-falling-drop.animate {
    animation: fallingDrop 0.5s ease-in forwards;
}

@keyframes fallingDrop {
    0% {
        opacity: 1;
        top: 20px;
        transform: scale(1);
    }
    80% {
        opacity: 1;
        top: 100px;
        transform: scale(1);
    }
    100% {
        opacity: 0;
        top: 110px;
        transform: scale(1.5);
    }
}

/* Drop animation indicator - legacy */
.demo-drops-indicator {
    display: none;
    opacity: 0;
}

.demo-drops-indicator.show {
    opacity: 1;
}

.demo-drop {
    width: 8px;
    height: 12px;
    background: var(--color-secondary);
    border-radius: 50% 50% 50% 50% / 30% 30% 70% 70%;
    animation: dropFall 0.6s ease forwards;
    opacity: 0;
}

.demo-drop:nth-child(2) {
    animation-delay: 0.15s;
}

@keyframes dropFall {
    0% {
        opacity: 1;
        transform: translateY(0);
    }
    100% {
        opacity: 0;
        transform: translateY(60px);
    }
}

/* Instructions */
.demo-instructions {
    text-align: center;
}

.demo-instructions h3 {
    font-size: 1.25rem;
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-white);
    margin-bottom: 0.75rem;
}

.demo-instructions p {
    font-size: var(--font-size-body);
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

/* Action Button */
.demo-action-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 1.5rem;
    background: var(--color-secondary);
    color: var(--color-primary-dark);
    border: none;
    border-radius: var(--radius-pill);
    font-size: var(--font-size-body);
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all 0.2s ease;
}

.demo-action-btn:hover {
    background: #fff;
    transform: scale(1.05);
}

.demo-action-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.demo-action-btn svg {
    width: 20px;
    height: 20px;
}

/* Drop Counter */
.demo-drop-counter {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 1.5rem;
}

.demo-drop-count {
    font-size: 3rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-secondary);
    line-height: 1;
}

.demo-drop-label {
    font-size: var(--font-size-small);
    color: rgba(255, 255, 255, 0.5);
}

/* Titration Counter */
.demo-titration-counter {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 1rem;
}

.demo-titration-btn {
    width: 56px;
    height: 56px;
    border: none;
    border-radius: 50%;
    font-size: 1.75rem;
    font-weight: var(--font-weight-bold);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.demo-titration-btn.minus {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.7);
}

.demo-titration-btn.plus {
    background: var(--color-secondary);
    color: var(--color-primary-dark);
}

.demo-titration-btn:hover:not(:disabled) {
    transform: scale(1.1);
}

.demo-titration-btn.plus:hover {
    background: #fff;
}

.demo-titration-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
    transform: none;
}

.demo-titration-display {
    text-align: center;
    min-width: 80px;
}

.demo-titration-count {
    font-size: 3rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-white);
    line-height: 1;
    display: block;
}

.demo-titration-label {
    font-size: var(--font-size-small);
    color: rgba(255, 255, 255, 0.5);
}

/* Calculation Display */
.demo-calculation {
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-small);
    padding: 1rem;
    margin-bottom: 1.5rem;
    text-align: center;
}

.demo-calc-value {
    font-size: 2rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-secondary);
}

.demo-calc-unit {
    font-size: var(--font-size-small);
    color: rgba(255, 255, 255, 0.6);
    display: block;
    margin-top: 0.25rem;
}

.demo-calculate-btn {
    background: var(--color-accent);
}

/* Results */
.demo-result-container {
    text-align: center;
    padding: 2rem 0;
}

.demo-result-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #4ade80 0%, #22c55e 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    animation: resultPop 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes resultPop {
    0% { transform: scale(0); }
    100% { transform: scale(1); }
}

.demo-result-icon svg {
    width: 40px;
    height: 40px;
    color: #fff;
}

.demo-result-title {
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-white);
    margin-bottom: 1rem;
}

.demo-result-value {
    margin-bottom: 1rem;
}

.demo-result-value span:first-child {
    font-size: 4rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-secondary);
    line-height: 1;
}

.demo-result-unit {
    font-size: 1.25rem;
    color: rgba(255, 255, 255, 0.7);
    margin-left: 0.5rem;
}

.demo-result-status {
    margin-bottom: 1.5rem;
}

.demo-status-badge {
    display: inline-block;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-pill);
    font-size: var(--font-size-small);
    font-weight: var(--font-weight-semibold);
    margin-bottom: 0.5rem;
}

.demo-status-badge.ideal {
    background: rgba(74, 222, 128, 0.2);
    color: #4ade80;
}

.demo-status-badge.low {
    background: rgba(251, 191, 36, 0.2);
    color: #fbbf24;
}

.demo-status-badge.high {
    background: rgba(239, 68, 68, 0.2);
    color: #ef4444;
}

.demo-result-status p {
    font-size: var(--font-size-body);
    color: rgba(255, 255, 255, 0.7);
}

.demo-result-info {
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-small);
    padding: 1rem;
}

.demo-result-info p {
    font-size: var(--font-size-small);
    color: rgba(255, 255, 255, 0.6);
    margin: 0;
}

/* Demo Footer */
.demo-footer {
    display: flex;
    justify-content: space-between;
    padding: 1rem 2rem 2rem;
    gap: 1rem;
}

.demo-nav-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 1.5rem;
    border: none;
    border-radius: var(--radius-pill);
    font-size: var(--font-size-body);
    font-weight: var(--font-weight-medium);
    cursor: pointer;
    transition: all 0.2s ease;
}

.demo-nav-btn.prev {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.7);
}

.demo-nav-btn.prev:hover:not(:disabled) {
    background: rgba(255, 255, 255, 0.2);
    color: #fff;
}

.demo-nav-btn.next {
    background: var(--color-secondary);
    color: var(--color-primary-dark);
    margin-left: auto;
}

.demo-nav-btn.next:hover:not(:disabled) {
    background: #fff;
    transform: scale(1.02);
}

.demo-nav-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.demo-nav-btn svg {
    width: 18px;
    height: 18px;
}

/* Demo Responsive */
@media (max-width: 480px) {
    .demo-container {
        max-height: 95vh;
        border-radius: var(--radius-medium);
    }

    .demo-header {
        padding: 1.5rem 1.5rem 1rem;
    }

    .demo-content {
        padding: 1rem 1.5rem 1.5rem;
        min-height: 350px;
    }

    .demo-footer {
        padding: 1rem 1.5rem 1.5rem;
    }

    .demo-tube {
        height: 150px;
        width: 50px;
    }

    .demo-titration-count {
        font-size: 2.5rem;
    }

    .demo-result-value span:first-child {
        font-size: 3rem;
    }
}