:root {
  --bg: #0c0f12;
  --panel: #14171c;
  --muted: #7a8599;
  --text: #e9eef7;
  --primary: #ff4d4f;
  --primary-700: #d9363e;
  --success: #15b25d;
  --warning: #ffcf33;
  --accent: #7c5cff;
  --shadow: 0 20px 40px rgba(0, 0, 0, 0.35);
}
* { box-sizing: border-box }
html, body { height: 100% }
body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Liberation Sans", sans-serif;
  color: var(--text);
  background: radial-gradient(1200px 600px at 20% 0%, #14171c 0%, #0c0f12 50%, #0a0d10 100%);
  overflow-x: hidden;
}
.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 16px;
  padding: 16px 20px;
  background: rgba(12, 15, 18, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}
.brand .logo {
  font-size: 26px;
  filter: drop-shadow(0 4px 8px rgba(0,0,0,0.3));
}
.brand h1 {
  margin: 0;
  font-size: 20px;
  letter-spacing: 0.2px;
}
.tagline {
  margin: 0;
  font-size: 12px;
  color: var(--muted);
}
.progress {
  display: flex;
  gap: 8px;
  font-size: 13px;
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scroll-snap-type: x mandatory;
  padding-bottom: 4px;
}
.progress-step {
  padding: 8px 10px;
  border-radius: 999px;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.08);
  color: var(--muted);
  transition: all .25s ease;
  flex: 0 0 auto;
  scroll-snap-align: start;
  white-space: nowrap;
}
.progress-step.active {
  color: var(--text);
  background: linear-gradient(90deg, rgba(255,77,79,.24), rgba(124,92,255,.24));
  border-color: rgba(255,255,255,0.18);
}
.builder {
  display: grid;
  grid-template-columns: 1fr minmax(280px, 360px);
  gap: 20px;
  padding: 20px;
}
.step {
  background: var(--panel);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 16px;
  transition: opacity .25s ease, transform .25s ease;
}
.step.hidden {
  opacity: 0.0;
  transform: translateY(8px);
  pointer-events: none;
  height: 0;
  padding: 0;
  border: 0;
  margin: 0;
}
.step-header h2 {
  margin: 0 0 12px 0;
  font-size: 16px;
}
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 14px;
}
.card {
  position: relative;
  border-radius: 14px;
  overflow: hidden;
  background: #0f1317;
  border: 1px solid rgba(255,255,255,0.08);
  transition: transform .25s ease, box-shadow .25s ease;
  cursor: pointer;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 14px 30px rgba(0,0,0,0.35);
}
.card img {
  width: 100%;
  height: 140px;
  object-fit: cover;
  display: block;
  background: #0a0d10;
}
.card-body {
  padding: 12px;
  display: grid;
  gap: 8px;
}
.price {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
}
.price .strike {
  color: var(--muted);
  text-decoration: line-through;
  font-weight: 400;
}
.badge {
  position: absolute;
  top: 10px;
  left: 10px;
  padding: 6px 10px;
  border-radius: 999px;
  font-size: 12px;
  background: #1a1f26;
  border: 1px solid rgba(255,255,255,0.08);
}
.badge.hot { background: linear-gradient(90deg, #ff4d4f, #ff7a45); color: #fff; border: none }
.stock-low {
  position: absolute;
  bottom: 10px;
  left: 10px;
  padding: 6px 10px;
  border-radius: 999px;
  font-size: 12px;
  background: rgba(255, 207, 51, 0.12);
  border: 1px solid rgba(255, 207, 51, 0.5);
  color: #ffd76b;
}
.overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.55);
  display: grid;
  place-items: center;
  font-weight: 700;
  letter-spacing: .4px;
  color: #fff;
}
.options {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.option {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.08);
  background: rgba(255,255,255,0.06);
  cursor: pointer;
  transition: all .25s ease;
}
.option img {
  width: 26px;
  height: 26px;
  object-fit: cover;
  border-radius: 50%;
}
.option.active {
  background: linear-gradient(90deg, rgba(124,92,255,.24), rgba(255,77,79,.24));
  border-color: rgba(255,255,255,0.18);
}
.controls {
  display: flex;
  gap: 10px;
  margin-top: 14px;
}
.btn {
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid rgba(255,255,255,0.08);
  background: rgba(255,255,255,0.06);
  color: var(--text);
  cursor: pointer;
  transition: all .25s ease;
}
.btn:hover { transform: translateY(-2px) }
.btn.primary { background: var(--accent); border-color: transparent }
.btn.secondary { background: #1a1f26 }
.btn.success { background: var(--success); border-color: transparent }
.btn.danger { background: #2a1a1a }
.btn.qty { background: #1a1f26 }
.btn.checkout { background: var(--primary); border-color: transparent }
.btn[disabled] { opacity: .5; cursor: not-allowed; transform: none }
.review {
  display: grid;
  gap: 8px;
  padding: 12px;
  border-radius: 12px;
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.06);
}
.qty-controls { display: flex; gap: 8px; margin: 12px 0 }
.cart {
  position: sticky;
  top: 92px;
  height: calc(100vh - 120px);
  display: grid;
  grid-template-rows: auto 1fr auto;
  gap: 10px;
  padding: 16px;
  background: var(--panel);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 16px;
  box-shadow: var(--shadow);
}
.cart-header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 10px;
}
.cart-header h3 {
  margin: 0;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.cart-header-right {
  display: flex;
  align-items: center;
  gap: 10px;
  justify-content: flex-end;
  flex-wrap: wrap;
}
.cart-total {
  white-space: nowrap;
}
.btn.cart-toggle {
  display: none;
  padding: 8px 10px;
  border-radius: 999px;
}
.cart-items {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
  overflow: auto;
}
.cart-item {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 6px;
  padding: 10px;
  border-radius: 12px;
  background: rgba(255,255,255,0.04);
}
.cart-item .title { font-weight: 600 }
.cart-item .meta { color: var(--muted); font-size: 12px }
.cart-item .price { font-weight: 700 }
.cart-actions { display: flex; gap: 10px }
.cart-bounce { animation: cart-bounce .6s ease }
@keyframes cart-bounce {
  0% { transform: translateY(0) }
  30% { transform: translateY(-6px) }
  60% { transform: translateY(0) }
  80% { transform: translateY(-2px) }
  100% { transform: translateY(0) }
}
@media (max-width: 900px) {
  .builder { grid-template-columns: 1fr }
  body { padding-bottom: 112px }
  .cart {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    max-height: 44vh;
    overflow: hidden;
    border-top-left-radius: 16px;
    border-top-right-radius: 16px;
    border-bottom-left-radius: 0;
    border-bottom-right-radius: 0;
  }
  .btn.cart-toggle { display: inline-flex }
  .cart.collapsed {
    max-height: 78px;
  }
  .cart.collapsed .cart-items,
  .cart.collapsed .cart-actions {
    display: none;
  }
}

@media (max-width: 640px) {
  .app-header {
    grid-template-columns: 1fr;
    align-items: start;
    padding: 14px 14px;
    gap: 10px;
  }

  .progress {
    width: 100%;
    padding-bottom: 6px;
  }
}

@media (max-width: 420px) {
  .progress-step {
    padding: 7px 9px;
    font-size: 12px;
  }

  .brand h1 {
    font-size: 18px;
  }
}