:root {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --text-primary: #f8fafc;
  --text-muted: #94a3b8;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --card-border: #334155;
  --tag-bg: rgba(99, 102, 241, 0.15);
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --text-primary: #0f172a;
  --text-muted: #64748b;
  --accent: #4f46e5;
  --accent-hover: #4338ca;
  --card-border: #e2e8f0;
  --tag-bg: rgba(79, 70, 229, 0.1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  transition: background-color 0.25s ease, color 0.25s ease;
}

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

/* Header & Nav */
header {
  border-bottom: 1px solid var(--card-border);
  background: var(--bg-secondary);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-container {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.5rem;
}

.brand {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
}

.brand span {
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 1.2rem;
  align-items: center;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
}

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

.theme-toggle-btn {
  background: transparent;
  border: 1px solid var(--card-border);
  color: var(--text-primary);
  padding: 0.4rem 0.8rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.9rem;
}

/* Main Container */
.container {
  max-width: 1100px;
  margin: 2rem auto;
  padding: 0 1.5rem;
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 4rem 1rem 2rem;
}

.hero h1 {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
}

.tagline {
  color: var(--accent);
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 1.2rem;
}

.hero p {
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
}

.btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 600;
}

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

/* Product Cards Grid */
.product-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.card {
  background: var(--bg-secondary);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 6px;
  background: var(--tag-bg);
  color: var(--accent);
  margin-bottom: 0.8rem;
}

.price {
  font-size: 1.4rem;
  font-weight: 700;
  margin: 1rem 0;
  color: var(--text-primary);
}

/* Proofs Gallery (Samsung F07 aspect ratio ~ 20:9 vertical format) */
.gallery-controls {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.select-dropdown {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--card-border);
  padding: 0.5rem 1rem;
  border-radius: 6px;
  outline: none;
  cursor: pointer;
}

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1.2rem;
}

.proof-item {
  background: var(--bg-secondary);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.proof-item img {
  width: 100%;
  aspect-ratio: 9 / 20; /* Samsung vertical aspect ratio */
  object-fit: cover;
  display: block;
  cursor: pointer;
}

.proof-caption {
  padding: 0.6rem;
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Floating WhatsApp Button */
.whatsapp-float {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 56px;
  height: 56px;
  background-color: #25d366;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
  z-index: 999;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  text-decoration: none;
}

.whatsapp-float:hover {
  transform: scale(1.08);
  box-shadow: 0 6px 16px rgba(37, 211, 102, 0.4);
}

.whatsapp-float svg {
  width: 32px;
  height: 32px;
  fill: #ffffff;
}

/* ===================================================
   RESPONSIVE OPTIMIZATIONS (Tablets & Mobile Screens)
   =================================================== */

/* Tablet & Mobile adjustment */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }

  .hero {
    padding: 2.5rem 0.5rem 1.5rem;
  }

  .gallery-controls {
    flex-direction: column;
    align-items: flex-start;
  }

  .gallery-controls > div:last-child {
    width: 100%;
  }

  .select-dropdown {
    width: 100%;
  }
}

/* Small mobile devices (e.g., phones under 480px) */
@media (max-width: 480px) {
  .nav-container {
    flex-direction: column;
    gap: 0.8rem;
    padding: 0.8rem 1rem;
  }

  .nav-links {
    width: 100%;
    justify-content: space-around;
    gap: 0.5rem;
    font-size: 0.9rem;
  }

  .theme-toggle-btn {
    padding: 0.3rem 0.6rem;
    font-size: 0.8rem;
  }

  .product-grid {
    grid-template-columns: 1fr; /* Full width cards on mobile */
  }

  .gallery-grid {
    grid-template-columns: repeat(2, 1fr); /* 2 clean vertical columns for screenshots */
    gap: 0.75rem;
  }

  .whatsapp-float {
    bottom: 16px;
    right: 16px;
    width: 50px;
    height: 50px;
  }

  .whatsapp-float svg {
    width: 28px;
    height: 28px;
  }
}