:root {
  --primary: #1f6feb;
  --primary-dark: #164b9c;
  --danger: #d1242f;
  --bg: #f6f8fa;
  --text: #1f2328;
  --border: #d0d7de;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

.topbar { background: #fff; border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 10; }
.topbar-inner { display: flex; align-items: center; gap: 20px; padding: 14px 20px; flex-wrap: wrap; }
.brand { font-weight: 700; font-size: 1.3rem; text-decoration: none; color: var(--text); }
.search-form { flex: 1; display: flex; gap: 6px; min-width: 200px; }
.search-form input { flex: 1; padding: 8px 10px; border: 1px solid var(--border); border-radius: 6px; }
.search-form button { padding: 8px 14px; border: none; border-radius: 6px; background: var(--primary); color: #fff; cursor: pointer; }
.nav-links { display: flex; align-items: center; gap: 14px; }
.nav-links a { text-decoration: none; color: var(--text); }
.nav-links .hello { color: #57606a; font-size: 0.9rem; }

main.container { padding-top: 24px; padding-bottom: 60px; min-height: 60vh; }

.flash { padding: 12px 16px; border-radius: 6px; margin-bottom: 16px; }
.flash-success { background: #dafbe1; color: #116329; border: 1px solid #4ac26b; }
.flash-error { background: #ffebe9; color: #82071e; border: 1px solid #ff8182; }

.page-title { margin-bottom: 18px; }

.category-bar { display: flex; gap: 10px; margin-bottom: 16px; flex-wrap: wrap; }
.category-bar a { padding: 6px 14px; border-radius: 999px; background: #fff; border: 1px solid var(--border); text-decoration: none; color: var(--text); font-size: 0.9rem; }
.category-bar a.active { background: var(--primary); color: #fff; border-color: var(--primary); }

.product-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 18px; }
.product-card { background: #fff; border: 1px solid var(--border); border-radius: 10px; overflow: hidden; text-decoration: none; color: var(--text); transition: box-shadow 0.15s; }
.product-card:hover { box-shadow: 0 4px 14px rgba(0,0,0,0.08); }
.product-img img { width: 100%; height: 170px; object-fit: cover; display: block; }
.img-placeholder { height: 170px; display: flex; align-items: center; justify-content: center; background: #eaeef2; color: #8b949e; }
.img-placeholder.large { height: 320px; border-radius: 10px; }
.product-info { padding: 12px 14px; }
.product-info h3 { margin: 0 0 6px; font-size: 1rem; }
.price { font-weight: 700; color: var(--primary-dark); margin: 4px 0; }
.price.large { font-size: 1.5rem; }
.stock { font-size: 0.85rem; color: #1a7f37; }
.stock.out { color: var(--danger); }

.product-detail { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; background: #fff; padding: 24px; border-radius: 10px; border: 1px solid var(--border); }
.product-detail-img img { width: 100%; border-radius: 10px; }
.add-to-cart-form { display: flex; align-items: center; gap: 12px; margin-top: 16px; }
.add-to-cart-form input[type=number] { width: 70px; padding: 6px; border: 1px solid var(--border); border-radius: 6px; }

.btn-primary { display: inline-block; background: var(--primary); color: #fff; border: none; padding: 10px 20px; border-radius: 6px; cursor: pointer; text-decoration: none; font-size: 0.95rem; }
.btn-primary:hover { background: var(--primary-dark); }

.cart-table, .admin-table { width: 100%; border-collapse: collapse; background: #fff; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.cart-table th, .cart-table td, .admin-table th, .admin-table td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: left; }
.cart-summary { margin-top: 18px; display: flex; align-items: center; gap: 20px; }
.total { font-size: 1.2rem; font-weight: 700; }

.inline-form { display: inline; }
.link-btn { background: none; border: none; color: var(--primary); cursor: pointer; text-decoration: underline; padding: 0; font-size: 0.9rem; }
.link-btn.danger { color: var(--danger); }

.checkout-layout { display: grid; grid-template-columns: 1.3fr 1fr; gap: 30px; }
.checkout-form, .order-summary { background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 20px; }
.checkout-form label, .auth-box label, .product-form label { display: block; margin-bottom: 14px; font-size: 0.9rem; }
.checkout-form input, .checkout-form textarea, .auth-box input, .product-form input, .product-form textarea { width: 100%; padding: 8px 10px; margin-top: 4px; border: 1px solid var(--border); border-radius: 6px; }
.note { font-size: 0.85rem; color: #57606a; background: #fff8c5; padding: 10px; border-radius: 6px; }

.auth-box { max-width: 400px; margin: 0 auto; background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 26px; }
.success-box, .error-box { max-width: 500px; margin: 40px auto; background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 30px; text-align: center; }

.admin-nav { display: flex; gap: 16px; margin-bottom: 20px; }
.admin-nav a { text-decoration: none; color: var(--primary); font-weight: 600; }
.stat-cards { display: flex; gap: 18px; flex-wrap: wrap; }
.stat-card { background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 20px 28px; }
.stat-label { color: #57606a; margin: 0 0 6px; font-size: 0.85rem; }
.stat-value { font-size: 1.7rem; font-weight: 700; margin: 0; }

.admin-layout { display: grid; grid-template-columns: 360px 1fr; gap: 24px; align-items: start; }
.product-form { background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 18px; }
.checkbox { display: flex; align-items: center; gap: 8px; }

.site-footer { border-top: 1px solid var(--border); padding: 20px 0; color: #57606a; font-size: 0.85rem; }

@media (max-width: 800px) {
  .product-detail, .checkout-layout, .admin-layout { grid-template-columns: 1fr; }
}