/* ======================================================
   Friction Zero — Global Stylesheet
   Modern · Minimal · Premium
   ====================================================== */

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

:root {
  --color-bg:        #fafafa;
  --color-surface:   #ffffff;
  --color-text:      #1a1a1a;
  --color-muted:     #71717a;
  --color-accent:    #0d0d0d;
  --color-accent-fg: #ffffff;
  --color-border:    #e4e4e7;
  --color-highlight: #e0f2fe;
  --font-body:       'Inter', 'Helvetica Neue', Arial, sans-serif;
  --font-display:    'Inter', 'Helvetica Neue', Arial, sans-serif;
  --radius:          8px;
  --max-width:       1120px;
  --transition:      0.25s ease;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
}

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

a {
  color: inherit;
  text-decoration: none;
}

/* ---------- Typography ---------- */
h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2rem, 5vw, 3.25rem); }
h2 { font-size: clamp(1.5rem, 3.5vw, 2.25rem); }
h3 { font-size: 1.15rem; }

p { max-width: 640px; }

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

/* ---------- Layout Helpers ---------- */
.container {
  width: 90%;
  max-width: var(--max-width);
  margin: 0 auto;
}

.section { padding: 80px 0; }
.section--alt { background: var(--color-surface); }

.flex { display: flex; gap: 2rem; }
.flex--center { align-items: center; justify-content: center; }

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 32px;
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
}

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

.btn--primary:hover {
  background: #333;
  transform: translateY(-2px);
}

.btn--outline {
  background: transparent;
  color: var(--color-accent);
  border: 1.5px solid var(--color-accent);
}

.btn--outline:hover {
  background: var(--color-accent);
  color: var(--color-accent-fg);
}

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 250, 250, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  text-transform: uppercase;
}

.logo span { font-weight: 300; }

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

.nav-links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-muted);
  transition: color var(--transition);
}

.nav-links a:hover,
.nav-links a.active { color: var(--color-text); }

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

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  transition: var(--transition);
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  display: flex;
  align-items: center;
  min-height: calc(100vh - 64px);
  padding: 60px 0;
  overflow: hidden;
}

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

.hero__bg-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
}

.hero__bg::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(250,250,250,0.92) 40%, rgba(250,250,250,0.3) 100%);
}

.hero .container {
  position: relative;
  z-index: 1;
}

.hero__content { max-width: 540px; }
.hero__content h1 { margin-bottom: 1rem; }

.hero__content p {
  color: var(--color-muted);
  font-size: 1.1rem;
  margin-bottom: 2rem;
}

.hero__actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.hero__image {
  position: relative;
  display: flex;
  justify-content: center;
}

.hero__product-img {
  width: 100%;
  max-width: 360px;
  height: auto;
  filter: drop-shadow(0 20px 40px rgba(0,0,0,0.15));
  animation: float 4s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-12px); }
}

/* ---------- Product Scene ---------- */
.product-scene { background: var(--color-bg); }

.product-scene__image img {
  width: 100%;
  border-radius: 16px;
  box-shadow: 0 12px 40px rgba(0,0,0,0.08);
}

.product-scene__content {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.product-scene__content h2 { margin-bottom: 1rem; }
.product-scene__content p { margin-bottom: 2rem; }

/* ---------- Features ---------- */
.features { text-align: center; }
.features h2 { margin-bottom: 0.75rem; }
.features > .container > p { margin: 0 auto 3rem; }

.features__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.feature-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem;
  text-align: left;
  transition: box-shadow var(--transition), transform var(--transition);
}

.feature-card:hover {
  box-shadow: 0 8px 30px rgba(0,0,0,0.06);
  transform: translateY(-4px);
}

.feature-card .icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background: var(--color-highlight);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 1.25rem;
}

.feature-card h3 { margin-bottom: 0.5rem; }

.feature-card p {
  color: var(--color-muted);
  font-size: 0.92rem;
}

/* ---------- Testimonials ---------- */
.testimonials { text-align: center; }
.testimonials h2 { margin-bottom: 2.5rem; }

.testimonials__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  text-align: left;
}

.testimonial-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem;
}

.testimonial-card blockquote {
  font-style: italic;
  color: var(--color-muted);
  margin-bottom: 1rem;
  line-height: 1.7;
}

.testimonial-card .author {
  font-weight: 600;
  font-size: 0.9rem;
}

/* ---------- CTA Banner ---------- */
.cta-banner {
  text-align: center;
  background: var(--color-accent);
  color: var(--color-accent-fg);
  padding: 80px 0;
}

.cta-banner h2 { color: #fff; margin-bottom: 0.75rem; }
.cta-banner p { color: #d4d4d8; margin: 0 auto 2rem; }

.cta-banner .btn--primary {
  background: #fff;
  color: var(--color-accent);
}

.cta-banner .btn--primary:hover { background: #e4e4e7; }

/* ---------- Product Page ---------- */
.product-hero { padding: 80px 0 40px; }
.product-hero .grid-2 { gap: 4rem; }

.product-gallery__img {
  width: 100%;
  max-width: 480px;
  height: auto;
  border-radius: 16px;
  filter: drop-shadow(0 16px 40px rgba(0,0,0,0.12));
  transition: transform var(--transition);
}

.product-gallery__img:hover { transform: scale(1.03); }

.product-info .price {
  font-size: 1.75rem;
  font-weight: 700;
  margin: 0.75rem 0 1rem;
}

.product-info .short-desc {
  color: var(--color-muted);
  margin-bottom: 1.5rem;
  font-size: 1rem;
}

.product-info .meta-list {
  list-style: none;
  margin-bottom: 2rem;
}

.product-info .meta-list li {
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.92rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.product-info .meta-list li::before {
  content: '✓';
  color: #22c55e;
  font-weight: 700;
}

.quantity-selector {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  margin-right: 1rem;
  overflow: hidden;
}

.quantity-selector button {
  width: 40px;
  height: 40px;
  background: var(--color-surface);
  border: none;
  font-size: 1.1rem;
  cursor: pointer;
  transition: background var(--transition);
}

.quantity-selector button:hover { background: var(--color-border); }

.quantity-selector input {
  width: 48px;
  height: 40px;
  text-align: center;
  border: none;
  border-left: 1px solid var(--color-border);
  border-right: 1px solid var(--color-border);
  font-size: 0.95rem;
  font-family: var(--font-body);
}

.product-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-top: 0.5rem;
}

/* ---------- Product Details Tabs ---------- */
.product-details { padding: 40px 0 80px; }

.tabs {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 2rem;
}

.tab-btn {
  padding: 12px 24px;
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-muted);
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition);
}

.tab-btn:hover,
.tab-btn.active {
  color: var(--color-text);
  border-bottom-color: var(--color-accent);
}

.tab-panel {
  display: none;
  max-width: 720px;
  line-height: 1.8;
  color: var(--color-muted);
}

.tab-panel.active { display: block; }

.tab-panel h3 {
  color: var(--color-text);