/* =====================================================================
   STUDENT DEMO STORE - MODERN STYLING (Vanilla CSS)
   ===================================================================== */

:root {
  --bg-dark: #0f172a;
  --bg-card: #1e293b;
  --bg-card-hover: #293548;
  --border-color: #334155;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --accent: #8b5cf6;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
  --radius-lg: 16px;
  --radius-md: 10px;
  --radius-sm: 6px;
  --transition: all 0.3s ease;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Plus Jakarta Sans', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

body {
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--accent);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  width: 100%;
}

/* --- Header / Navbar --- */
.navbar {
  background: rgba(30, 41, 59, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 1rem 0;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.4rem;
  font-weight: 800;
  background: linear-gradient(135deg, #60a5fa 0%, #a78bfa 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.logo-icon {
  font-size: 1.6rem;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

.nav-link {
  color: var(--text-muted);
  font-weight: 500;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
}

.nav-link:hover, .nav-link.active {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.05);
}

.admin-badge {
  background: rgba(139, 92, 246, 0.15);
  color: var(--accent);
  border: 1px solid rgba(139, 92, 246, 0.3);
  padding: 0.4rem 0.9rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
}

.admin-badge:hover {
  background: var(--accent);
  color: #fff;
}

/* --- Hero Banner --- */
.hero {
  padding: 3.5rem 0 2.5rem;
  text-align: center;
  background: radial-gradient(circle at 50% 20%, rgba(59, 130, 246, 0.15) 0%, transparent 60%);
}

.hero-tag {
  display: inline-block;
  background: rgba(59, 130, 246, 0.15);
  color: #60a5fa;
  border: 1px solid rgba(59, 130, 246, 0.3);
  padding: 0.35rem 1rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

.hero-title {
  font-size: 2.75rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 650px;
  margin: 0 auto 1.5rem;
}

/* --- Alert Messages --- */
.alert {
  padding: 1rem 1.25rem;
  border-radius: var(--radius-md);
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-weight: 500;
}

.alert-success {
  background: rgba(16, 185, 129, 0.15);
  border: 1px solid rgba(16, 185, 129, 0.4);
  color: #34d399;
}

.alert-danger {
  background: rgba(239, 68, 68, 0.15);
  border: 1px solid rgba(239, 68, 68, 0.4);
  color: #f87171;
}

.alert-warning {
  background: rgba(245, 158, 11, 0.15);
  border: 1px solid rgba(245, 158, 11, 0.4);
  color: #fbbf24;
}

/* --- Category Filter & Section --- */
.catalog-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 700;
}

.category-filters {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.filter-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.5rem 1rem;
  border-radius: 999px;
  font-size: 0.875rem;
  cursor: pointer;
  transition: var(--transition);
}

.filter-btn:hover, .filter-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

/* --- Product Grid & Cards --- */
.product-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.75rem;
  margin-bottom: 4rem;
}

.product-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
  position: relative;
}

.product-card:hover {
  transform: translateY(-6px);
  border-color: rgba(59, 130, 246, 0.5);
  box-shadow: var(--shadow-lg);
  background: var(--bg-card-hover);
}

.product-img-wrapper {
  position: relative;
  width: 100%;
  height: 200px;
  overflow: hidden;
  background: #0f172a;
}

.product-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: var(--transition);
}

.product-card:hover .product-img {
  transform: scale(1.06);
}

.category-tag {
  position: absolute;
  top: 12px;
  left: 12px;
  background: rgba(15, 23, 42, 0.75);
  backdrop-filter: blur(6px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: #fff;
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
}

.stock-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  background: rgba(16, 185, 129, 0.2);
  border: 1px solid rgba(16, 185, 129, 0.4);
  color: #34d399;
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
}

.stock-badge.low-stock {
  background: rgba(245, 158, 11, 0.2);
  border-color: rgba(245, 158, 11, 0.4);
  color: #fbbf24;
}

.stock-badge.out-stock {
  background: rgba(239, 68, 68, 0.2);
  border-color: rgba(239, 68, 68, 0.4);
  color: #f87171;
}

.product-body {
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.product-title {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.product-desc {
  color: var(--text-muted);
  font-size: 0.875rem;
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.product-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: auto;
  padding-top: 0.75rem;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.product-price {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.9rem;
  border: none;
  cursor: pointer;
  transition: var(--transition);
}

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

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

.btn-secondary {
  background: var(--border-color);
  color: var(--text-main);
}

.btn-secondary:hover {
  background: #475569;
}

.btn-disabled {
  background: #334155;
  color: #64748b;
  cursor: not-allowed;
}

/* --- Modal Popup --- */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(8px);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  padding: 1rem;
}

.modal-overlay.active {
  display: flex;
}

.modal {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  max-width: 500px;
  width: 100%;
  padding: 2rem;
  box-shadow: var(--shadow-lg);
  position: relative;
  animation: modalFadeIn 0.25s ease-out;
}

@keyframes modalFadeIn {
  from { opacity: 0; transform: scale(0.95); }
  to { opacity: 1; transform: scale(1); }
}

.modal-close {
  position: absolute;
  top: 1.25rem;
  right: 1.25rem;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.5rem;
  cursor: pointer;
}

.modal-close:hover {
  color: var(--text-main);
}

.modal-title {
  font-size: 1.4rem;
  margin-bottom: 0.5rem;
}

.modal-subtitle {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
}

/* --- Form Fields --- */
.form-group {
  margin-bottom: 1.25rem;
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--text-main);
}

.form-control {
  width: 100%;
  padding: 0.75rem 1rem;
  background: #0f172a;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 0.95rem;
  outline: none;
  transition: var(--transition);
}

.form-control:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.25);
}

/* --- Admin Dashboard --- */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 1.5rem;
  border-radius: var(--radius-lg);
}

.stat-title {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.stat-value {
  font-size: 2rem;
  font-weight: 800;
  color: var(--text-main);
}

.table-wrapper {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  margin-bottom: 3rem;
}

.table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.table th, .table td {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
}

.table th {
  background: rgba(15, 23, 42, 0.5);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.table tr:last-child td {
  border-bottom: none;
}

.table tr:hover td {
  background: rgba(255, 255, 255, 0.02);
}

.badge {
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  display: inline-block;
}

.badge-success {
  background: rgba(16, 185, 129, 0.15);
  color: #34d399;
}

.badge-warning {
  background: rgba(245, 158, 11, 0.15);
  color: #fbbf24;
}

/* --- Footer --- */
.footer {
  margin-top: auto;
  border-top: 1px solid var(--border-color);
  padding: 2rem 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
  background: #0f172a;
}