/* ============================================
   FERN — Precision Fuel System
   Design System & Styles
   Inspired by Maurten's minimal aesthetic
   White background + Blue accent
   ============================================ */

/* --- Google Fonts --- */
@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&family=Noto+Sans+KR:wght@300;400;500;700&family=Space+Mono:wght@400;700&display=swap');

/* --- CSS Custom Properties (Design Tokens) --- */
:root {
  /* Colors */
  --color-bg: #FAFAFA;
  --color-bg-white: #FFFFFF;
  --color-bg-subtle: #F5F5F5;
  --color-bg-section: #F0F2F5;
  --color-bg-dark: #050505;
  --color-bg-dark-subtle: #1A1A1A;

  --color-text-primary: #050505;
  --color-text-secondary: #4D4D4D;
  --color-text-tertiary: #767676;
  --color-text-dimmed: #999999;
  --color-text-inverse: #FAFAFA;

  --color-accent: #0A4DCD;
  --color-accent-hover: #083FA8;
  --color-accent-light: #E6EEFC;
  --color-accent-dark: #07399B;

  --color-border: #E6E6E6;
  --color-border-subtle: #F0F0F0;
  --color-border-strong: #050505;

  --color-success: #107839;
  --color-error: #AE0000;

  /* Typography */
  --font-body: 'Noto Sans KR', system-ui, -apple-system, sans-serif;
  --font-heading: 'Space Grotesk', 'Noto Sans KR', sans-serif;
  --font-mono: 'Space Mono', ui-monospace, monospace;

  /* Font Sizes - Fluid Typography */
  --text-xs: 0.75rem;    /* 12px */
  --text-sm: 0.875rem;   /* 14px */
  --text-base: 1rem;     /* 16px */
  --text-lg: clamp(1.125rem, 1.04rem + 0.27vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1.08rem + 0.54vw, 1.5rem);
  --text-2xl: clamp(1.5rem, 1.16rem + 1.08vw, 2rem);
  --text-3xl: clamp(1.75rem, 1.41rem + 1.08vw, 2.25rem);
  --text-4xl: clamp(2rem, 1.49rem + 1.62vw, 2.75rem);
  --text-5xl: clamp(2.5rem, 1.82rem + 2.16vw, 3.5rem);
  --text-6xl: clamp(3rem, 1.99rem + 3.24vw, 4.5rem);
  --text-hero: clamp(4rem, 2.65rem + 4.32vw, 6rem);

  /* Spacing */
  --space-3xs: 4px;
  --space-2xs: 8px;
  --space-xs: 12px;
  --space-s: 16px;
  --space-m: 24px;
  --space-l: 32px;
  --space-xl: 48px;
  --space-2xl: 64px;
  --space-3xl: 96px;
  --space-4xl: 128px;

  /* Grid */
  --grid-gap: 20px;
  --container-max: 1400px;
  --container-narrow: 900px;

  /* Borders */
  --radius-xs: 2px;
  --radius-s: 4px;
  --radius-m: 8px;
  --radius-l: 12px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;
  --transition-smooth: 600ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 16px 50px rgba(0, 0, 0, 0.15);

  /* Header */
  --header-height: 60px;
  --header-height-desktop: 74px;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  font-size: 16px;
}

body {
  min-height: 100vh;
  font-family: var(--font-body);
  font-weight: 400;
  line-height: 1.5;
  color: var(--color-text-primary);
  background-color: var(--color-bg);
  text-rendering: geometricPrecision;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

input, textarea {
  font-family: inherit;
  font-size: inherit;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
}

h1 { font-size: var(--text-5xl); }
h2 { font-size: var(--text-4xl); }
h3 { font-size: var(--text-3xl); }
h4 { font-size: var(--text-2xl); }
h5 { font-size: var(--text-xl); }
h6 { font-size: var(--text-lg); }

p {
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text-secondary);
}

.text-mono {
  font-family: var(--font-mono);
}

.text-accent {
  color: var(--color-accent);
}

.text-dimmed {
  color: var(--color-text-tertiary);
}

.text-small {
  font-size: var(--text-sm);
}

.text-xs {
  font-size: var(--text-xs);
}

/* --- Layout --- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-m);
}

.container--narrow {
  max-width: var(--container-narrow);
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--grid-gap);
}

.section {
  padding: var(--space-3xl) 0;
}

.section--compact {
  padding: var(--space-2xl) 0;
}

.section--dark {
  background-color: var(--color-bg-dark);
  color: var(--color-text-inverse);
}

.section--dark h1,
.section--dark h2,
.section--dark h3,
.section--dark h4 {
  color: var(--color-text-inverse);
}

.section--dark p {
  color: rgba(250, 250, 250, 0.7);
}

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

/* --- Header / Navigation --- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-height);
  transition: background-color var(--transition-base), 
              box-shadow var(--transition-base),
              backdrop-filter var(--transition-base);
}

.header::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  opacity: 0;
  transition: opacity var(--transition-base);
  z-index: -1;
}

.header.is-scrolled::before {
  opacity: 1;
}

.header.is-scrolled {
  box-shadow: 0 1px 0 var(--color-border);
}

.header__content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-m);
}

.header__logo {
  display: flex;
  align-items: center;
  text-decoration: none;
  z-index: 1001;
}

.header__logo img {
  height: 24px;
  width: auto;
  object-fit: contain;
  transition: opacity var(--transition-fast);
}

.header__logo:hover img {
  opacity: 0.8;
}

.header__logo-sub {
  display: none;
}

.header__nav {
  display: none;
  align-items: center;
  gap: var(--space-l);
}

.header__nav-link {
  position: relative;
  font-size: var(--text-sm);
  font-weight: 400;
  color: var(--color-text-tertiary);
  text-decoration: none;
  letter-spacing: 0.02em;
  transition: color var(--transition-fast);
  padding: var(--space-2xs) 0;
}

.header__nav-link:hover,
.header__nav-link.is-active {
  color: var(--color-text-primary);
}

.header__nav-link.is-active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 1px;
  background-color: var(--color-text-primary);
}

.header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-s);
  z-index: 1001;
}

.header__cart-btn {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--space-3xs);
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  transition: color var(--transition-fast);
  padding: var(--space-2xs);
}

.header__cart-btn:hover {
  color: var(--color-text-primary);
}

.header__cart-count {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 18px;
  height: 18px;
  padding: 0 5px;
  border-radius: 9px;
  background-color: var(--color-accent);
  color: white;
  font-size: 11px;
  font-weight: 600;
  line-height: 1;
}

.header__cart-count:empty,
.header__cart-count[data-count="0"] {
  display: none;
}

/* Mobile Menu Toggle */
.header__menu-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 24px;
  height: 24px;
  padding: 0;
  z-index: 1001;
}

.header__menu-toggle span {
  display: block;
  width: 100%;
  height: 1.5px;
  background-color: var(--color-text-primary);
  transition: transform var(--transition-base), opacity var(--transition-fast);
  transform-origin: center;
}

.header__menu-toggle.is-open span:nth-child(1) {
  transform: translateY(6.5px) rotate(45deg);
}
.header__menu-toggle.is-open span:nth-child(2) {
  opacity: 0;
}
.header__menu-toggle.is-open span:nth-child(3) {
  transform: translateY(-6.5px) rotate(-45deg);
}

/* Mobile Navigation */
.mobile-nav {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 999;
  background-color: var(--color-bg);
  padding-top: var(--header-height);
  overflow-y: auto;
}

.mobile-nav.is-open {
  display: flex;
  flex-direction: column;
  animation: fadeIn 0.2s ease;
}

.mobile-nav__content {
  display: flex;
  flex-direction: column;
  padding: var(--space-l) var(--space-m);
  gap: var(--space-xs);
}

.mobile-nav__link {
  font-size: var(--text-2xl);
  font-weight: 400;
  color: var(--color-text-primary);
  padding: var(--space-xs) 0;
  border-bottom: 1px solid var(--color-border);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.mobile-nav__link:hover {
  color: var(--color-accent);
}

.mobile-nav__bottom {
  margin-top: auto;
  padding: var(--space-l) var(--space-m);
  border-top: 1px solid var(--color-border);
}

/* --- Hero Section --- */
.hero {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  min-height: 100dvh;
  padding-top: var(--header-height);
  overflow: hidden;
  background-color: var(--color-bg);
}

.hero__content {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: var(--space-2xl) var(--space-m);
  max-width: 800px;
}

.hero__eyebrow {
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-m);
}

.hero__title {
  font-size: var(--text-hero);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 0.95;
  margin-bottom: var(--space-m);
  color: var(--color-text-primary);
}

.hero__subtitle {
  font-size: var(--text-lg);
  font-weight: 300;
  color: var(--color-text-tertiary);
  max-width: 500px;
  line-height: 1.5;
  margin-bottom: var(--space-xl);
}

.hero__image {
  position: relative;
  width: 100%;
  max-width: 400px;
  margin: var(--space-xl) auto 0;
}

.hero__image img {
  width: 100%;
  height: auto;
  object-fit: contain;
  filter: drop-shadow(0 20px 60px rgba(0, 0, 0, 0.1));
}

.hero__scroll-indicator {
  position: absolute;
  bottom: var(--space-l);
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2xs);
  color: var(--color-text-dimmed);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  animation: float 2s ease-in-out infinite;
}

.hero__scroll-indicator svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2xs);
  min-width: 120px;
  height: 48px;
  padding: 0 var(--space-m);
  border: none;
  border-radius: var(--radius-s);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: 0.02em;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition-base);
}

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

.btn--primary:hover {
  background-color: var(--color-accent-hover);
  color: white;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn--secondary {
  background-color: var(--color-bg-dark);
  color: var(--color-text-inverse);
}

.btn--secondary:hover {
  background-color: var(--color-bg-dark-subtle);
  color: var(--color-text-inverse);
  transform: translateY(-1px);
}

.btn--outline {
  background-color: transparent;
  color: var(--color-text-primary);
  border: 1px solid var(--color-border-strong);
}

.btn--outline:hover {
  background-color: var(--color-text-primary);
  color: var(--color-text-inverse);
}

.btn--ghost {
  background: none;
  color: var(--color-text-primary);
  min-width: auto;
  height: auto;
  padding: var(--space-2xs) 0;
  border-radius: 0;
  font-weight: 400;
}

.btn--ghost:hover {
  color: var(--color-accent);
}

.btn--ghost::after {
  content: '→';
  display: inline-block;
  transition: transform var(--transition-fast);
}

.btn--ghost:hover::after {
  transform: translateX(4px);
}

.btn--lg {
  height: 56px;
  padding: 0 var(--space-l);
  font-size: var(--text-base);
}

.btn--sm {
  height: 36px;
  padding: 0 var(--space-s);
  font-size: var(--text-xs);
  min-width: 80px;
}

.btn--full {
  width: 100%;
}

/* --- Key Metrics Section --- */
.metrics {
  padding: var(--space-3xl) 0;
  background-color: var(--color-bg-white);
}

.metrics__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-m);
}

.metrics__item {
  text-align: center;
  padding: var(--space-l);
}

.metrics__number {
  font-family: var(--font-mono);
  font-size: var(--text-hero);
  font-weight: 700;
  line-height: 1;
  color: var(--color-text-primary);
  margin-bottom: var(--space-xs);
}

.metrics__unit {
  font-size: var(--text-3xl);
  font-weight: 400;
  color: var(--color-text-tertiary);
}

.metrics__label {
  font-size: var(--text-sm);
  font-weight: 400;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
}

.metrics__divider {
  display: none;
  width: 1px;
  background-color: var(--color-border);
  align-self: stretch;
}

/* --- Product Section --- */
.product-showcase {
  padding: var(--space-3xl) 0;
}

.product-showcase__header {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.product-showcase__header h2 {
  margin-bottom: var(--space-s);
}

.product-showcase__header p {
  max-width: 500px;
  margin: 0 auto;
}

/* Product Card */
.product-card {
  position: relative;
  display: flex;
  flex-direction: column;
  background-color: var(--color-bg-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-m);
  overflow: hidden;
  transition: transform var(--transition-base), box-shadow var(--transition-base);
  text-decoration: none;
  color: inherit;
}

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

.product-card__image {
  position: relative;
  aspect-ratio: 1;
  background-color: var(--color-bg-subtle);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-l);
}

.product-card__image img {
  width: 70%;
  height: auto;
  object-fit: contain;
  transition: transform var(--transition-slow);
}

.product-card:hover .product-card__image img {
  transform: scale(1.05);
}

.product-card__badge {
  position: absolute;
  top: var(--space-s);
  left: var(--space-s);
  padding: 4px 10px;
  background-color: var(--color-accent);
  color: white;
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  border-radius: var(--radius-xs);
}

.product-card__info {
  padding: var(--space-m);
}

.product-card__name {
  font-size: var(--text-base);
  font-weight: 500;
  margin-bottom: var(--space-3xs);
}

.product-card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-s);
  line-height: 1.4;
}

.product-card__price {
  font-family: var(--font-mono);
  font-size: var(--text-base);
  font-weight: 500;
}

.product-card__price-original {
  text-decoration: line-through;
  color: var(--color-text-dimmed);
  margin-left: var(--space-2xs);
  font-weight: 400;
}

/* Product Grid */
.product-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-m);
}

/* --- Product Detail Page --- */
.product-detail {
  padding-top: calc(var(--header-height) + var(--space-xl));
}

.product-detail__layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-2xl);
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-m);
}

.product-detail__gallery {
  position: relative;
  background-color: var(--color-bg-subtle);
  border-radius: var(--radius-m);
  padding: var(--space-2xl);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 400px;
}

.product-detail__gallery img {
  max-width: 80%;
  max-height: 500px;
  object-fit: contain;
  filter: drop-shadow(0 10px 40px rgba(0, 0, 0, 0.08));
}

.product-detail__info {
  display: flex;
  flex-direction: column;
  gap: var(--space-m);
}

.product-detail__eyebrow {
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-accent);
}

.product-detail__title {
  font-size: var(--text-4xl);
  font-weight: 600;
}

.product-detail__subtitle {
  font-size: var(--text-lg);
  color: var(--color-text-tertiary);
  font-weight: 300;
}

.product-detail__price {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 500;
}

.product-detail__description {
  font-size: var(--text-base);
  color: var(--color-text-secondary);
  line-height: 1.7;
  padding-bottom: var(--space-m);
  border-bottom: 1px solid var(--color-border);
}

/* Quantity Selector */
.qty-selector {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-s);
  overflow: hidden;
}

.qty-selector__btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  transition: background-color var(--transition-fast);
}

.qty-selector__btn:hover {
  background-color: var(--color-bg-subtle);
}

.qty-selector__value {
  width: 48px;
  text-align: center;
  font-family: var(--font-mono);
  font-size: var(--text-base);
  border-left: 1px solid var(--color-border);
  border-right: 1px solid var(--color-border);
  line-height: 44px;
}

/* Product Specs Table */
.specs-table {
  width: 100%;
  border-collapse: collapse;
}

.specs-table th,
.specs-table td {
  padding: var(--space-xs) 0;
  font-size: var(--text-sm);
  border-bottom: 1px solid var(--color-border);
  text-align: left;
}

.specs-table th {
  font-weight: 400;
  color: var(--color-text-tertiary);
  width: 40%;
}

.specs-table td {
  font-family: var(--font-mono);
  font-weight: 400;
  color: var(--color-text-primary);
}

/* --- Science Section --- */
.science {
  padding: var(--space-3xl) 0;
}

.science__hero {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.science__hero h2 {
  margin-bottom: var(--space-m);
}

.science__features {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
}

.science__feature {
  display: flex;
  flex-direction: column;
  gap: var(--space-m);
  padding: var(--space-l);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-m);
  transition: border-color var(--transition-base);
}

.science__feature:hover {
  border-color: var(--color-accent);
}

.science__feature-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-m);
  background-color: var(--color-accent-light);
  color: var(--color-accent);
  font-size: var(--text-xl);
}

.science__feature h4 {
  font-size: var(--text-lg);
  font-weight: 500;
}

.science__feature p {
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-text-secondary);
}

/* --- About Section --- */
.about__hero {
  position: relative;
  min-height: 60vh;
  display: flex;
  align-items: center;
  background-color: var(--color-bg-subtle);
  overflow: hidden;
}

.about__content {
  position: relative;
  z-index: 2;
  max-width: 600px;
  padding: var(--space-3xl) var(--space-m);
}

.about__text-block {
  padding: var(--space-3xl) 0;
}

.about__text-block p {
  font-size: var(--text-lg);
  line-height: 1.8;
  max-width: 700px;
}

/* --- Newsletter Section --- */
.newsletter {
  padding: var(--space-3xl) 0;
  background-color: var(--color-bg-subtle);
}

.newsletter__content {
  text-align: center;
  max-width: 500px;
  margin: 0 auto;
}

.newsletter__content h3 {
  margin-bottom: var(--space-xs);
}

.newsletter__content p {
  margin-bottom: var(--space-l);
}

.newsletter__form {
  display: flex;
  gap: var(--space-2xs);
}

.newsletter__input {
  flex: 1;
  height: 48px;
  padding: 0 var(--space-s);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-s);
  background-color: var(--color-bg-white);
  font-size: var(--text-sm);
  transition: border-color var(--transition-fast);
}

.newsletter__input:focus {
  outline: none;
  border-color: var(--color-accent);
}

.newsletter__input::placeholder {
  color: var(--color-text-dimmed);
}

/* --- Cart Page --- */
.cart-page {
  padding-top: calc(var(--header-height) + var(--space-xl));
  min-height: 100vh;
}

.cart-page__layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-2xl);
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-m) var(--space-3xl);
}

.cart-page__header {
  margin-bottom: var(--space-l);
}

.cart-page__header h1 {
  font-size: var(--text-3xl);
}

.cart-page__empty {
  text-align: center;
  padding: var(--space-3xl) 0;
}

.cart-page__empty p {
  margin-bottom: var(--space-l);
}

/* Cart Item */
.cart-item {
  display: grid;
  grid-template-columns: 80px 1fr auto;
  gap: var(--space-m);
  padding: var(--space-m) 0;
  border-bottom: 1px solid var(--color-border);
  align-items: center;
}

.cart-item__image {
  width: 80px;
  height: 80px;
  background-color: var(--color-bg-subtle);
  border-radius: var(--radius-s);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-xs);
}

.cart-item__image img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.cart-item__info {
  display: flex;
  flex-direction: column;
  gap: var(--space-3xs);
}

.cart-item__name {
  font-size: var(--text-base);
  font-weight: 500;
}

.cart-item__variant {
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
}

.cart-item__actions {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: var(--space-xs);
}

.cart-item__price {
  font-family: var(--font-mono);
  font-size: var(--text-base);
  font-weight: 500;
}

.cart-item__remove {
  font-size: var(--text-xs);
  color: var(--color-text-dimmed);
  text-decoration: underline;
  transition: color var(--transition-fast);
}

.cart-item__remove:hover {
  color: var(--color-error);
}

/* Cart Summary */
.cart-summary {
  background-color: var(--color-bg-subtle);
  padding: var(--space-l);
  border-radius: var(--radius-m);
  position: sticky;
  top: calc(var(--header-height) + var(--space-m));
}

.cart-summary__row {
  display: flex;
  justify-content: space-between;
  padding: var(--space-xs) 0;
  font-size: var(--text-sm);
}

.cart-summary__row--total {
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-s);
  padding-top: var(--space-m);
  font-size: var(--text-lg);
  font-weight: 500;
}

.cart-summary__row--total span:last-child {
  font-family: var(--font-mono);
}

/* --- Footer --- */
.footer {
  background-color: var(--color-bg-dark);
  color: var(--color-text-inverse);
  padding: var(--space-3xl) 0 var(--space-l);
}

.footer__top {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  padding-bottom: var(--space-2xl);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer__brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-s);
}

.footer__logo {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
}

.footer__logo img {
  height: 28px;
  width: auto;
  object-fit: contain;
  filter: brightness(0) invert(1);
  opacity: 0.9;
}

.footer__brand p {
  font-size: var(--text-sm);
  color: rgba(255, 255, 255, 0.5);
  max-width: 300px;
  line-height: 1.6;
}

.footer__nav {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-l);
}

.footer__nav-group h5 {
  font-size: var(--text-sm);
  font-weight: 500;
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: var(--space-s);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.footer__nav-group a {
  display: block;
  font-size: var(--text-sm);
  color: rgba(255, 255, 255, 0.4);
  padding: var(--space-3xs) 0;
  transition: color var(--transition-fast);
  text-decoration: none;
}

.footer__nav-group a:hover {
  color: rgba(255, 255, 255, 0.8);
}

.footer__bottom {
  display: flex;
  flex-direction: column;
  gap: var(--space-s);
  padding-top: var(--space-l);
  font-size: var(--text-xs);
  color: rgba(255, 255, 255, 0.3);
}

.footer__bottom a {
  color: rgba(255, 255, 255, 0.3);
  text-decoration: none;
}

.footer__bottom a:hover {
  color: rgba(255, 255, 255, 0.6);
}

.footer__social {
  display: flex;
  gap: var(--space-s);
}

.footer__social a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: rgba(255, 255, 255, 0.5);
  font-size: var(--text-sm);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.footer__social a:hover {
  border-color: rgba(255, 255, 255, 0.4);
  color: rgba(255, 255, 255, 0.9);
  transform: translateY(-2px);
}

/* --- Animations --- */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes float {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(-8px); }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

/* Scroll Reveal */
.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.reveal--delay-1 { transition-delay: 0.1s; }
.reveal--delay-2 { transition-delay: 0.2s; }
.reveal--delay-3 { transition-delay: 0.3s; }
.reveal--delay-4 { transition-delay: 0.4s; }

/* Counter Animation */
.counter {
  display: inline-block;
}

/* --- Utility Classes --- */
.u-text-center { text-align: center; }
.u-text-left { text-align: left; }
.u-text-right { text-align: right; }

.u-flex { display: flex; }
.u-flex-center { display: flex; align-items: center; justify-content: center; }
.u-flex-between { display: flex; align-items: center; justify-content: space-between; }

.u-mt-xs { margin-top: var(--space-xs); }
.u-mt-s { margin-top: var(--space-s); }
.u-mt-m { margin-top: var(--space-m); }
.u-mt-l { margin-top: var(--space-l); }
.u-mt-xl { margin-top: var(--space-xl); }
.u-mt-2xl { margin-top: var(--space-2xl); }

.u-mb-xs { margin-bottom: var(--space-xs); }
.u-mb-s { margin-bottom: var(--space-s); }
.u-mb-m { margin-bottom: var(--space-m); }
.u-mb-l { margin-bottom: var(--space-l); }
.u-mb-xl { margin-bottom: var(--space-xl); }

.u-gap-xs { gap: var(--space-xs); }
.u-gap-s { gap: var(--space-s); }
.u-gap-m { gap: var(--space-m); }
.u-gap-l { gap: var(--space-l); }

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* --- Page Transition --- */
.page-content {
  animation: fadeIn 0.4s ease;
}

/* --- Ingredient Row (for product detail) --- */
.ingredient-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: var(--space-xs) 0;
  border-bottom: 1px dotted var(--color-border);
}

.ingredient-row__name {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
}

.ingredient-row__amount {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-text-primary);
}

/* --- How to Use Section --- */
.how-to-use {
  padding: var(--space-2xl);
  background-color: var(--color-bg-subtle);
  border-radius: var(--radius-m);
  margin-top: var(--space-xl);
}

.how-to-use__title {
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-m);
}

.how-to-use__step {
  display: flex;
  gap: var(--space-m);
  padding: var(--space-s) 0;
}

.how-to-use__step-num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-accent);
  min-width: 24px;
}

.how-to-use__step-text {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* --- Tagline / Quote Section --- */
.tagline-section {
  padding: var(--space-4xl) 0;
  text-align: center;
}

.tagline-section__text {
  font-size: var(--text-4xl);
  font-weight: 500;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--color-accent);
  max-width: 700px;
  margin: 0 auto;
}

/* --- Feature Band --- */
.feature-band {
  display: grid;
  grid-template-columns: 1fr;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.feature-band__item {
  padding: var(--space-l) var(--space-m);
  text-align: center;
  border-bottom: 1px solid var(--color-border);
}

.feature-band__item:last-child {
  border-bottom: none;
}

.feature-band__value {
  font-family: var(--font-mono);
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: var(--space-3xs);
}

.feature-band__label {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
}

/* --- Image Section (Full Width) --- */
.full-image-section {
  position: relative;
  width: 100%;
  height: 60vh;
  min-height: 400px;
  overflow: hidden;
}

.full-image-section img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.full-image-section__overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.3);
}

.full-image-section__overlay h2 {
  color: white;
  font-size: var(--text-5xl);
  text-align: center;
}

/* --- Notification Toast --- */
.toast {
  position: fixed;
  bottom: var(--space-l);
  right: var(--space-l);
  z-index: 2000;
  display: flex;
  align-items: center;
  gap: var(--space-s);
  padding: var(--space-s) var(--space-m);
  background-color: var(--color-bg-dark);
  color: var(--color-text-inverse);
  border-radius: var(--radius-m);
  box-shadow: var(--shadow-xl);
  font-size: var(--text-sm);
  transform: translateY(100px);
  opacity: 0;
  transition: all var(--transition-smooth);
  pointer-events: none;
}

.toast.is-visible {
  transform: translateY(0);
  opacity: 1;
  pointer-events: auto;
}

.toast__icon {
  color: var(--color-success);
}

/* --- Responsive Design --- */

/* Tablet: 768px+ */
@media screen and (min-width: 768px) {
  :root {
    --header-height: var(--header-height-desktop);
  }

  .header__logo-sub {
    display: inline;
  }

  .header__menu-toggle {
    display: none;
  }

  .header__nav {
    display: flex;
  }

  .metrics__grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .metrics__divider {
    display: block;
  }

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

  .product-detail__layout {
    grid-template-columns: 1fr 1fr;
    align-items: start;
  }

  .product-detail__gallery {
    position: sticky;
    top: calc(var(--header-height) + var(--space-m));
  }

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

  .feature-band {
    grid-template-columns: repeat(4, 1fr);
  }

  .feature-band__item {
    border-bottom: none;
    border-right: 1px solid var(--color-border);
  }

  .feature-band__item:last-child {
    border-right: none;
  }

  .footer__top {
    grid-template-columns: 1fr 2fr;
  }

  .footer__nav {
    grid-template-columns: repeat(3, 1fr);
  }

  .footer__bottom {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }

  .cart-page__layout {
    grid-template-columns: 2fr 1fr;
  }
}

/* Desktop: 1024px+ */
@media screen and (min-width: 1024px) {
  .product-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .science__features {
    grid-template-columns: repeat(3, 1fr);
  }

  .hero__content {
    padding: var(--space-3xl) var(--space-m);
  }

  .newsletter__form {
    max-width: 400px;
    margin: 0 auto;
  }

  .footer__nav {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* Large Desktop: 1400px+ */
@media screen and (min-width: 1400px) {
  .product-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* --- Print Styles --- */
@media print {
  .header,
  .footer,
  .mobile-nav,
  .toast,
  .hero__scroll-indicator {
    display: none !important;
  }

  body {
    color: #000;
    background: #fff;
  }

  .section--dark {
    background: #fff;
    color: #000;
  }
}

/* --- Competitor Comparison & Rebranding UI --- */
.comp-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-l);
  margin-top: var(--space-xl);
}

@media screen and (min-width: 768px) {
  .comp-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.comp-card {
  background-color: var(--color-bg-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-l);
  padding: var(--space-xl);
  position: relative;
  transition: all var(--transition-base);
  display: flex;
  flex-direction: column;
  gap: var(--space-s);
}

.comp-card--bad {
  border-left: 4px solid var(--color-text-dimmed);
}

.comp-card--good {
  border-left: 4px solid var(--color-accent);
  box-shadow: var(--shadow-md);
}

.comp-card--good:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.comp-badge {
  display: inline-block;
  padding: 4px var(--space-2xs);
  font-family: var(--font-heading);
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  border-radius: var(--radius-xs);
  align-self: flex-start;
}

.comp-badge--bad {
  background-color: var(--color-bg-subtle);
  color: var(--color-text-tertiary);
}

.comp-badge--good {
  background-color: var(--color-accent-light);
  color: var(--color-accent);
}

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

.comp-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2xs);
  list-style: none;
  padding: 0;
  margin: var(--space-xs) 0 0;
}

.comp-list-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-2xs);
  font-size: var(--text-sm);
  line-height: 1.6;
}

.comp-list-item::before {
  font-family: var(--font-mono);
  font-weight: 700;
  flex-shrink: 0;
}

.comp-card--bad .comp-list-item::before {
  content: '✕';
  color: var(--color-error);
}

.comp-card--good .comp-list-item::before {
  content: '✓';
  color: var(--color-success);
}

/* Watermark logo decoration */
.logo-watermark {
  position: absolute;
  top: 10%;
  right: 5%;
  width: 300px;
  height: 300px;
  opacity: 0.02;
  pointer-events: none;
  z-index: 1;
}

.logo-watermark img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

/* Brand Story styling */
.brand-story-section {
  position: relative;
  overflow: hidden;
  padding: var(--space-4xl) 0;
  background-color: var(--color-bg-white);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.brand-story-logo {
  display: flex;
  justify-content: center;
  margin-bottom: var(--space-l);
}

.brand-story-logo img {
  height: 60px;
  width: auto;
  object-fit: contain;
}