/* ============================================
   AEROBI — Style Principal
   Site vitrine poudre d'électrolytes
   ============================================ */

/* ---------- Google Fonts ---------- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Poppins:wght@600;700;800&display=swap');
/* ============================================
   VARIABLES CSS & THÈMES
   ============================================ */

/* --- 1. THÈME PAR DÉFAUT (Bleu Hydratation) --- */
:root, [data-theme="defaut"] {
  --color-primary: #3a8fbf;
  --color-primary-light: #6bb5db;
  --color-primary-dark: #2a6d96;
  --color-secondary: #56c4a2;
  --color-secondary-light: #83d9be;
  --color-accent: #f0a844;
  --color-accent-light: #f7c97a;
  
  --color-bg: #ffffff;
  --color-bg-alt: #f5f9fc;
  --color-bg-dark: #0f2b3c;
  --color-text: #1e293b;
  --color-text-light: #64748b;
  --color-text-inverse: #ffffff;
  --color-border: #e2e8f0;
  
  --color-cta: #3a8fbf;
  --color-cta-hover: #2a6d96;
  --color-cta-text: #ffffff;
  
  --color-card-shadow: rgba(58, 143, 191, 0.08);
  --color-hero-overlay: rgba(15, 43, 60, 0.55);
}

/* --- 2. THÈME "BOTANIQUE" (Nature, Bien-être, Apaisant) --- */
[data-theme="botanique"] {
  --color-primary: #5a7a5a;
  --color-primary-light: #83a383;
  --color-primary-dark: #3f573f;
  --color-secondary: #d4a373;
  --color-secondary-light: #e6cba8;
  --color-accent: #e9c46a;
  --color-accent-light: #f4e2b3;
  
  --color-bg: #fdfdfc;
  --color-bg-alt: #f4f5f2;
  --color-bg-dark: #2c352c;
  --color-text: #2b302b;
  --color-text-light: #6b756b;
  --color-text-inverse: #ffffff;
  --color-border: #dcdedc;
  
  --color-cta: #5a7a5a;
  --color-cta-hover: #3f573f;
  --color-cta-text: #ffffff;
  
  --color-card-shadow: rgba(90, 122, 90, 0.08);
  --color-hero-overlay: rgba(44, 53, 44, 0.65);
}

/* --- 3. THÈME "ÉNERGIE" (Sport, Dynamique, Vitamines) --- */
[data-theme="energie"] {
  --color-primary: #d96c4a;
  --color-primary-light: #e89579;
  --color-primary-dark: #b55536;
  --color-secondary: #2d9cdb;
  --color-secondary-light: #7bc3eb;
  --color-accent: #f2c94c;
  --color-accent-light: #f7dea3;
  
  --color-bg: #ffffff;
  --color-bg-alt: #fff8f5;
  --color-bg-dark: #2b1b17;
  --color-text: #2b2220;
  --color-text-light: #73625e;
  --color-text-inverse: #ffffff;
  --color-border: #f0e1dd;
  
  --color-cta: #d96c4a;
  --color-cta-hover: #b55536;
  --color-cta-text: #ffffff;
  
  --color-card-shadow: rgba(217, 108, 74, 0.08);
  --color-hero-overlay: rgba(43, 27, 23, 0.7);
}

/* --- 4. THÈME "MINÉRAL" (Science, Premium, Pur) --- */
[data-theme="mineral"] {
  --color-primary: #5c7c8a;
  --color-primary-light: #88a3af;
  --color-primary-dark: #3a5360;
  --color-secondary: #7eb8a6;
  --color-secondary-light: #aed3c8;
  --color-accent: #e0a96d;
  --color-accent-light: #eed2b1;
  
  --color-bg: #fcfdfd;
  --color-bg-alt: #f0f3f5;
  --color-bg-dark: #1c2529;
  --color-text: #202a2e;
  --color-text-light: #6a7b82;
  --color-text-inverse: #ffffff;
  --color-border: #dbe2e6;
  
  --color-cta: #5c7c8a;
  --color-cta-hover: #3a5360;
  --color-cta-text: #ffffff;
  
  --color-card-shadow: rgba(92, 124, 138, 0.08);
  --color-hero-overlay: rgba(28, 37, 41, 0.65);
}

/* --- Couleurs utilitaires communes --- */
:root {
  --color-success-bg: #e8f5e9;
  --color-success-border: #a5d6a7;
  --color-success-text: #2e7d32;
  --color-bg-input: #ffffff;
  --color-footer-link-muted: rgba(255, 255, 255, 0.6);

  /* --- Typographie --- */
  --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-heading: 'Poppins', 'Inter', sans-serif;

  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-md: 1.125rem;
  --font-size-lg: 1.25rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 2.5rem;
  --font-size-4xl: 3.25rem;

  /* --- Espacement --- */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  --spacing-4xl: 6rem;

  /* --- Bordures --- */
  --radius-sm: 0.375rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  --radius-full: 9999px;

  /* --- Transitions --- */
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;

  /* --- Largeur max --- */
  --max-width: 1200px;
  --max-width-narrow: 800px;
}

/* ============================================
   RESET & BASE
   ============================================ */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 100%;
}

body {
  font-family: var(--font-main);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

ul, ol {
  list-style: none;
}

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  line-height: 1.2;
  color: var(--color-text);
}

/* ============================================
   UTILITAIRES
   ============================================ */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.section {
  padding: var(--spacing-4xl) 0;
}

.section-title {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  text-align: center;
  margin-bottom: var(--spacing-md);
}

.section-subtitle {
  font-size: var(--font-size-md);
  color: var(--color-text-light);
  text-align: center;
  max-width: var(--max-width-narrow);
  margin: 0 auto var(--spacing-3xl);
}

.icon {
  width: 24px;
  height: 24px;
  display: inline-block;
  vertical-align: middle;
  /* Permet de teinter les SVG via CSS filter */
  filter: brightness(0) saturate(100%);
  transition: filter var(--transition-fast);
}

.icon--sm { width: 18px; height: 18px; }
.icon--lg { width: 32px; height: 32px; }
.icon--xl { width: 48px; height: 48px; }

.icon--primary {
  filter: brightness(0) saturate(100%) invert(50%) sepia(60%) saturate(500%) hue-rotate(170deg) brightness(90%);
}

.icon--white {
  filter: brightness(0) saturate(100%) invert(100%);
}

.icon--accent {
  filter: brightness(0) saturate(100%) invert(70%) sepia(60%) saturate(500%) hue-rotate(0deg) brightness(100%);
}

.placeholder-img {
  background-color: var(--color-bg-alt);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-light);
  font-size: var(--font-size-sm);
  font-style: italic;
  overflow: hidden;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-xl);
  border-radius: var(--radius-full);
  font-family: var(--font-main);
  font-size: var(--font-size-base);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  text-align: center;
  justify-content: center;
}

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

.btn--primary:hover {
  background-color: var(--color-cta-hover);
  color: var(--color-cta-text);
  transform: translateY(-2px);
  box-shadow: 0 4px 15px var(--color-card-shadow);
}

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

.btn--outline:hover {
  background-color: var(--color-primary);
  color: var(--color-cta-text);
  transform: translateY(-2px);
}

.btn--lg {
  padding: var(--spacing-lg) var(--spacing-2xl);
  font-size: var(--font-size-md);
}

/* Animations d'apparition au scroll */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================
   HEADER / NAVIGATION
   ============================================ */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  transition: box-shadow var(--transition-base);
}

.header.scrolled {
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
}

.header__logo {
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.02em;
}

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

.header__nav {
  display: none;
  gap: var(--spacing-xl);
}

.header__nav a {
  color: var(--color-text);
  font-size: var(--font-size-sm);
  font-weight: 500;
  position: relative;
  padding: var(--spacing-xs) 0;
}

.header__nav a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  transition: width var(--transition-base);
}

.header__nav a:hover::after,
.header__nav a.active::after {
  width: 100%;
}

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

.header__actions {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.header__cta {
  display: none;
}

.header__hamburger {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
}

.header__hamburger .icon-open { display: block; }
.header__hamburger .icon-close { display: none; }

.header__hamburger.active .icon-open { display: none; }
.header__hamburger.active .icon-close { display: block; }

/* Menu mobile */
.mobile-menu {
  display: none;
  position: fixed;
  top: 70px;
  left: 0;
  width: 100%;
  height: calc(100vh - 70px);
  background-color: var(--color-bg);
  padding: var(--spacing-2xl) var(--spacing-lg);
  flex-direction: column;
  gap: var(--spacing-lg);
  z-index: 999;
}

.mobile-menu.open {
  display: flex;
}

.mobile-menu a {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--color-text);
  padding: var(--spacing-md) 0;
  border-bottom: 1px solid var(--color-border);
}

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

.mobile-menu .btn {
  margin-top: var(--spacing-lg);
  text-align: center;
}

/* ============================================
   HERO
   ============================================ */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 70px;
  background-color: var(--color-bg-alt);
  overflow: hidden;
}

.hero__bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.hero__bg .placeholder-img {
  width: 100%;
  height: 100%;
  border: none;
  border-radius: 0;
  font-size: var(--font-size-lg);
}

.hero__overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--color-hero-overlay) 0%, rgba(56, 143, 191, 0.3) 100%);
  z-index: 1;
}

.hero__content {
  position: relative;
  z-index: 2;
  max-width: 650px;
  padding: var(--spacing-3xl) 0;
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  background-color: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(5px);
  color: var(--color-text-inverse);
  font-size: var(--font-size-sm);
  font-weight: 500;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-full);
  margin-bottom: var(--spacing-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.hero__title {
  font-size: clamp(2rem, 6vw, var(--font-size-4xl));
  font-weight: 800;
  color: var(--color-text-inverse);
  margin-bottom: var(--spacing-lg);
  line-height: 1.1;
  white-space: nowrap;
}

.hero__title span {
  display: block;
  padding-left: 10rem;
  color: var(--color-secondary-light);
}

.hero__subtitle {
  font-size: var(--font-size-md);
  color: rgba(255, 255, 255, 0.85);
  margin-bottom: var(--spacing-2xl);
  line-height: 1.7;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.hero__actions .btn--outline {
  border-color: rgba(255, 255, 255, 0.5);
  color: var(--color-text-inverse);
}

.hero__actions .btn--outline:hover {
  background-color: rgba(255, 255, 255, 0.15);
  border-color: var(--color-text-inverse);
}

/* ============================================
   POURQUOI AEROBI
   ============================================ */
.why__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-xl);
}

.why__card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-2xl);
  text-align: center;
  transition: all var(--transition-base);
}

.why__card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 40px var(--color-card-shadow);
  border-color: var(--color-primary-light);
}

.why__card-icon {
  width: 64px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg-alt);
  border-radius: var(--radius-md);
  margin: 0 auto var(--spacing-lg);
}

.why__card-title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
}

.why__card-text {
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
  line-height: 1.7;
}

/* ============================================
   PRODUITS
   ============================================ */
.products {
  background-color: var(--color-bg-alt);
}

.products__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-2xl);
}

.product-card {
  background-color: var(--color-bg);
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: 0 4px 20px var(--color-card-shadow);
  transition: all var(--transition-base);
}

.product-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 40px rgba(58, 143, 191, 0.15);
}

.product-card__image {
  height: 250px;
  position: relative;
}

.product-card__image .placeholder-img {
  width: 100%;
  height: 100%;
  border: none;
  border-radius: 0;
}

.product-card__badge {
  position: absolute;
  top: var(--spacing-md);
  left: var(--spacing-md);
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
  font-size: var(--font-size-xs);
  font-weight: 600;
  padding: var(--spacing-xs) var(--spacing-md);
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.product-card__body {
  padding: var(--spacing-xl);
}

.product-card__name {
  font-size: var(--font-size-xl);
  font-weight: 700;
  margin-bottom: var(--spacing-xs);
}

.product-card__tagline {
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
  margin-bottom: var(--spacing-md);
}

.product-card__posologie {
  font-size: var(--font-size-sm);
  color: var(--color-text);
  background-color: var(--color-bg-alt);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-sm);
  margin-bottom: var(--spacing-lg);
  line-height: 1.6;
}

.product-card__ingredients {
  font-size: var(--font-size-xs);
  color: var(--color-text-light);
  margin-top: var(--spacing-md);
  line-height: 1.6;
}

.product-card__minerals {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-lg);
}

.mineral-tag {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  background-color: var(--color-bg-alt);
  padding: var(--spacing-xs) var(--spacing-md);
  border-radius: var(--radius-full);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-text);
}

.mineral-tag__value {
  color: var(--color-primary);
  font-weight: 600;
}

/* Accordion nutrition */
.nutrition-accordion {
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-md);
}

.nutrition-toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--spacing-md) 0;
  background: none;
  border: none;
  cursor: pointer;
  font-family: var(--font-main);
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text);
}

.nutrition-toggle .icon {
  transition: transform var(--transition-base);
}

.nutrition-toggle.active .icon {
  transform: rotate(180deg);
}

.nutrition-panel {
  display: none;
  padding-bottom: var(--spacing-md);
}

.nutrition-panel.open {
  display: block;
}

.nutrition-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--font-size-sm);
}

.nutrition-table th,
.nutrition-table td {
  padding: var(--spacing-sm) var(--spacing-md);
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.nutrition-table th {
  font-weight: 600;
  color: var(--color-text-light);
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.nutrition-table td:last-child {
  text-align: right;
  color: var(--color-primary);
  font-weight: 600;
}

.product-card__footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
}

.product-card__price {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-text);
}

.product-card__price-unit {
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
  font-weight: 400;
}

/* ============================================
   SCIENCE
   ============================================ */
.science__content {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-3xl);
  align-items: center;
}

.science__text p {
  color: var(--color-text-light);
  margin-bottom: var(--spacing-lg);
  line-height: 1.8;
}

.science__text p:first-of-type {
  font-size: var(--font-size-md);
}

.science__highlight {
  background-color: var(--color-bg-alt);
  border-left: 4px solid var(--color-primary);
  padding: var(--spacing-xl);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  margin-bottom: var(--spacing-lg);
}

.science__highlight p {
  margin-bottom: 0;
  font-weight: 500;
  color: var(--color-text);
}

.science__ions-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-md);
}

.ion-card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--spacing-lg);
  text-align: center;
  transition: all var(--transition-base);
}

.ion-card:hover {
  border-color: var(--color-primary-light);
  box-shadow: 0 4px 15px var(--color-card-shadow);
}

.ion-card__symbol {
  font-family: var(--font-heading);
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--spacing-xs);
}

.ion-card__name {
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.ion-card__role {
  font-size: var(--font-size-xs);
  color: var(--color-text-light);
}

/* ============================================
   FAQ
   ============================================ */
.faq {
  background-color: var(--color-bg-alt);
}

.faq__list {
  max-width: var(--max-width-narrow);
  margin: 0 auto;
}

.faq__item {
  background-color: var(--color-bg);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-md);
  overflow: hidden;
  border: 1px solid var(--color-border);
  transition: border-color var(--transition-base);
}

.faq__item:hover {
  border-color: var(--color-primary-light);
}

.faq__question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--spacing-lg) var(--spacing-xl);
  background: none;
  border: none;
  cursor: pointer;
  font-family: var(--font-main);
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--color-text);
  text-align: left;
  gap: var(--spacing-md);
}

.faq__question .icon {
  flex-shrink: 0;
  transition: transform var(--transition-base);
}

.faq__question.active .icon {
  transform: rotate(180deg);
}

.faq__question.active {
  color: var(--color-primary);
}

.faq__answer {
  display: none;
  padding: 0 var(--spacing-xl) var(--spacing-lg);
  color: var(--color-text-light);
  line-height: 1.7;
}

.faq__answer.open {
  display: block;
}

/* ============================================
   À PROPOS
   ============================================ */
.about__content {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-3xl);
  align-items: center;
}

.about__image .placeholder-img {
  width: 100%;
  height: 350px;
}

.about__text h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-lg);
}

.about__text p {
  color: var(--color-text-light);
  margin-bottom: var(--spacing-lg);
  line-height: 1.8;
}

.about__values {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-md);
  margin-top: var(--spacing-xl);
}

.about__value {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-md);
}

.about__value-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg-alt);
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.about__value-text h4 {
  font-size: var(--font-size-base);
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.about__value-text p {
  font-size: var(--font-size-sm);
  margin-bottom: 0;
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
  background-color: var(--color-bg-dark);
  color: rgba(255, 255, 255, 0.7);
  padding: var(--spacing-4xl) 0 var(--spacing-xl);
}

.footer__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-2xl);
  margin-bottom: var(--spacing-3xl);
}

.footer__brand-name {
  font-family: var(--font-heading);
  font-size: var(--font-size-xl);
  font-weight: 800;
  color: var(--color-text-inverse);
  margin-bottom: var(--spacing-md);
}

.footer__brand-desc {
  font-size: var(--font-size-sm);
  line-height: 1.7;
  margin-bottom: var(--spacing-lg);
}

.footer__social {
  display: flex;
  gap: var(--spacing-md);
}

.footer__social a {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-sm);
  transition: background-color var(--transition-base);
}

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

.footer__heading {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-inverse);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--spacing-lg);
}

.footer__links li {
  margin-bottom: var(--spacing-sm);
}

.footer__links a {
  font-size: var(--font-size-sm);
  color: rgba(255, 255, 255, 0.6);
  transition: color var(--transition-fast);
}

.footer__links a:hover {
  color: var(--color-text-inverse);
}

.footer__contact-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
  font-size: var(--font-size-sm);
}

.footer__bar {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-md);
  padding-top: var(--spacing-xl);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  font-size: var(--font-size-xs);
}

/* ============================================
   RESPONSIVE — Tablet (768px+)
   ============================================ */
@media (min-width: 768px) {
  .section-title {
    font-size: var(--font-size-3xl);
  }

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

  .why__card:nth-child(n) { grid-column: span 1; }

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

  .product-card--featured {
    grid-column: 1 / -1;
    max-width: 480px;
    margin: 0 auto;
    width: 100%;
  }

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

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

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

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

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

  .footer__bar {
    flex-direction: row;
    justify-content: space-between;
  }
}

/* ============================================
   RESPONSIVE — Desktop (1024px+)
   ============================================ */
@media (min-width: 1024px) {
  .header__nav {
    display: flex;
  }

  .header__cta {
    display: inline-flex;
  }

  .header__hamburger {
    display: none;
  }

  .why__grid {
    grid-template-columns: repeat(6, 1fr);
  }

  .why__card:nth-child(1) { grid-column: span 3; }
  .why__card:nth-child(2) { grid-column: span 3; }
  .why__card:nth-child(3) { grid-column: span 2; }
  .why__card:nth-child(4) { grid-column: span 2; }
  .why__card:nth-child(5) { grid-column: span 2; }

  .product-card__image {
    height: 300px;
  }
}