*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --primary: #0F172A;
  --secondary: #64748B;
  --accent: #38BDF8;
  --accent-text: #0C7BB3;
  --accent-fg: #0F172A;
  --gray-50: #F8FAFC;
  --gray-100: #F1F5F9;
  --gray-300: #CBD5E1;
  --gray-600: #475569;
  --gray-700: #334155;
  --white: #FFFFFF;
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  color: var(--primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

/* Focus */
:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}
:focus:not(:focus-visible) {
  outline: none;
}

/* Skip link */
.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 100;
  padding: 0.75rem 1.5rem;
  background: var(--accent); color: var(--accent-fg);
  font-weight: 600; font-size: 0.875rem;
}
.skip-link:focus { left: 1rem; top: 1rem; }

/* Layout */
.container { max-width: 72rem; margin: 0 auto; padding: 0 1rem; }
.section { padding: 6rem 1rem; }

/* Grid */
.grid-2 { display: grid; gap: 3rem; }
.grid-3 { display: grid; gap: 1.5rem; }
.grid-4 { display: grid; gap: 2rem; }
@media (min-width: 768px) {
  .grid-2 { grid-template-columns: 1fr 1fr; }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1024px) {
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(4, 1fr); }
}

/* Language switcher */
.lang-switch {
  position: fixed; top: 1rem; right: 1rem; z-index: 50;
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.75rem 1.25rem; min-height: 44px;
  background: rgba(255,255,255,0.1); backdrop-filter: blur(12px);
  border: 1px solid rgba(255,255,255,0.2); border-radius: 9999px;
  font-size: 0.875rem; font-weight: 500; color: var(--white);
  transition: background 0.2s;
}
.lang-switch:hover { background: rgba(255,255,255,0.2); }
.lang-switch svg { width: 1rem; height: 1rem; }

/* Hero */
.hero {
  position: relative; min-height: 100vh; display: flex; align-items: center; justify-content: center;
  padding: 5rem 1rem;
  background: linear-gradient(to right, rgba(15,23,42,0.95), rgba(15,23,42,0.8));
  color: var(--white); text-align: center;
}
.hero-badge {
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.5rem 1rem; margin-bottom: 2rem;
  background: rgba(56,189,248,0.1); border-radius: 9999px;
  font-size: 0.875rem; font-weight: 500; color: var(--accent);
}
.hero h1 { font-size: clamp(2.25rem, 5vw, 4.5rem); font-weight: 700; line-height: 1.1; margin-bottom: 2rem; letter-spacing: -0.02em; }
.hero h1 .accent { color: var(--accent); }
.hero p { color: var(--gray-300); font-size: 1.125rem; max-width: 42rem; margin: 0 auto 2.5rem; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 1rem; justify-content: center; }
.hero .scroll-hint {
  position: absolute; bottom: 2.5rem; left: 50%; transform: translateX(-50%);
  width: 2.75rem; height: 2.75rem; display: flex; align-items: center; justify-content: center;
  border: 1px solid rgba(255,255,255,0.2); border-radius: 50%;
  animation: bounce 2s infinite;
}

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 0.5rem;
  padding: 1rem 2rem; border-radius: 9999px; font-weight: 500; font-size: 1rem;
  border: none; cursor: pointer; transition: all 0.2s;
}
.btn-accent { background: var(--accent); color: var(--accent-fg); }
.btn-accent:hover { box-shadow: 0 10px 25px rgba(56,189,248,0.2); transform: scale(1.05); }
.btn-outline { background: transparent; border: 1px solid rgba(255,255,255,0.2); color: var(--white); }
.btn-outline:hover { background: rgba(255,255,255,0.1); }
.btn-outline-dark { background: transparent; border: 1px solid rgba(255,255,255,0.2); color: var(--white); }
.btn-outline-dark:hover { background: rgba(255,255,255,0.1); }

/* Sections */
.bg-white { background: var(--white); }
.bg-gray { background: var(--gray-50); }
.bg-dark {
  background: linear-gradient(135deg, #0F172A 0%, #1E293B 100%);
  color: var(--white);
}

.section-label {
  display: block; font-size: 0.875rem; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.05em; color: var(--accent-text);
  margin-bottom: 0.5rem;
}
.section-title { font-size: clamp(1.875rem, 3vw, 2.25rem); font-weight: 700; margin-bottom: 1rem; color: var(--primary); }
.section-desc { font-size: 1.125rem; color: var(--secondary); max-width: 42rem; margin: 0 auto 4rem; }
.text-center { text-align: center; }
.items-center { align-items: center; }

/* Feature cards */
.feature-card {
  padding: 2rem; background: var(--white); border-radius: 1rem;
  border: 1px solid var(--gray-100); box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  transition: box-shadow 0.3s;
}
.feature-card:hover { box-shadow: 0 10px 25px rgba(0,0,0,0.08); }
.feature-icon {
  width: 3.5rem; height: 3.5rem; background: rgba(56,189,248,0.1);
  border-radius: 1rem; display: flex; align-items: center; justify-content: center;
  margin-bottom: 1.5rem;
}
.feature-icon svg { width: 1.5rem; height: 1.5rem; color: var(--accent); }
.feature-card h3 { font-size: 1.25rem; font-weight: 600; margin-bottom: 0.75rem; }
.feature-card p { color: var(--secondary); }

/* Battery diagram */
.diagram-wrapper {
  max-width: 48rem; margin: 0 auto;
  background: var(--white); border-radius: 0.75rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.08); padding: 1rem;
}

/* Spec cards */
.spec-card {
  padding: 1.5rem; background: var(--white); border-radius: 0.75rem;
  border: 1px solid var(--gray-100); box-shadow: 0 1px 2px rgba(0,0,0,0.04);
  transition: box-shadow 0.3s;
}
.spec-card:hover { box-shadow: 0 4px 12px rgba(0,0,0,0.08); }
.spec-card dt { font-weight: 500; color: var(--secondary); margin-bottom: 0.5rem; }
.spec-card dd { font-size: 1.25rem; font-weight: 600; color: var(--primary); }

/* Custom batteries */
.custom-card {
  position: relative; width: 100%; max-width: 28rem; margin: 0 auto;
}
.custom-card-bg {
  position: absolute; inset: 0; background: rgba(56,189,248,0.1);
  border-radius: 1.5rem; transform: rotate(3deg);
}
.custom-card-inner {
  position: relative;
  background: linear-gradient(to bottom right, var(--primary), rgba(15,23,42,0.8));
  border-radius: 1.5rem; padding: 2.5rem; color: var(--white); text-align: center;
}
.custom-card-inner .emoji { font-size: 3.75rem; margin-bottom: 1rem; }
.custom-card-inner h3 { font-size: 1.5rem; font-weight: 700; margin-bottom: 0.5rem; }
.custom-card-inner p { color: rgba(255,255,255,0.7); }

.check-list li {
  display: flex; align-items: center; gap: 0.75rem;
  color: var(--secondary); margin-bottom: 0.75rem;
}
.check-list svg { width: 1.25rem; height: 1.25rem; color: var(--accent-text); flex-shrink: 0; }

/* CTA */
.cta .section-label { color: var(--accent); }
.cta .section-title { color: var(--white); }
.cta .section-desc { color: var(--gray-300); }
.cta-actions { display: flex; flex-wrap: wrap; gap: 1rem; justify-content: center; }

/* Footer */
.footer { background: var(--white); padding: 2rem 1rem; text-align: center; }
.footer a { display: inline-block; }
.footer img { height: 2.5rem; margin: 0 auto; }

/* Contact page */
.contact-back {
  display: inline-flex; align-items: center; gap: 0.5rem;
  color: var(--accent-text); font-weight: 500; margin-bottom: 2.5rem;
  transition: opacity 0.2s;
}
.contact-back:hover { opacity: 0.8; }
.contact-back svg { width: 1rem; height: 1rem; }

.contact-info { display: flex; flex-direction: column; gap: 1.5rem; }
.contact-item { display: flex; align-items: flex-start; gap: 1rem; }
.contact-icon {
  width: 2.75rem; height: 2.75rem; flex-shrink: 0;
  background: rgba(56,189,248,0.1); border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
}
.contact-icon svg { width: 1.25rem; height: 1.25rem; color: var(--accent); }
.contact-item h3 { font-weight: 500; font-size: 1.125rem; margin-bottom: 0.25rem; }
.contact-item p { color: var(--gray-600); }
.contact-item a { color: var(--accent-text); text-decoration: underline; text-underline-offset: 2px; }
.contact-item a:hover { color: var(--primary); }

.seller-box {
  background: var(--gray-50); padding: 2rem; border-radius: 0.75rem;
}
.seller-box h2 { font-size: 1.5rem; font-weight: 700; margin-bottom: 1.5rem; }
.seller-box dl > div { margin-bottom: 1rem; }
.seller-box dt { font-weight: 500; margin-bottom: 0.25rem; }
.seller-box dd { color: var(--gray-700); }

/* Animations */
@keyframes bounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(-8px); }
}
@keyframes fade-up {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}
.fade-up {
  animation: fade-up 0.7s ease-out both;
}
.fade-up-d1 { animation-delay: 0.1s; }
.fade-up-d2 { animation-delay: 0.2s; }
.fade-up-d3 { animation-delay: 0.3s; }
.fade-up-d4 { animation-delay: 0.4s; }

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

/* SVG icons inline */
svg { display: inline-block; vertical-align: middle; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }