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

:root {
  --primary: #0ea5e9;
  --primary-dark: #0284c7;
  --primary-light: #38bdf8;
  --secondary: #06b6d4;
  --accent: #38bdf8;
  --text-dark: #1f2937;
  --text-light: #6b7280;
  --bg-light: #f0f9ff;
  --bg-white: #ffffff;
  --border: #e0f2fe;
  --radius: 0.5rem;
}

html {
  scroll-behavior: smooth;
}

/* Thẻ img khai báo width/height để trình duyệt giữ chỗ trước khi ảnh tải (tránh CLS);
   height: auto giữ đúng tỉ lệ khi CSS của khối chỉ đặt chiều rộng. */
img {
  max-width: 100%;
  height: auto;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-dark);
  background-color: var(--bg-white);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ==================== HEADER ==================== */
.header {
  background: var(--bg-white);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 4px 20px rgba(14, 165, 233, 0.08);
  /* Enhanced shadow for more modern look */
  backdrop-filter: blur(10px);
  background: rgba(255, 255, 255, 0.95);
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
  gap: 40px;
}

.logo {
  display: flex;
  align-items: center;
}

.logo-image {
  height: 50px;
  width: auto;
  max-width: 200px;
  object-fit: contain;
  transition: transform 0.3s ease;
}

.logo-image:hover {
  transform: scale(1.05);
}

.logo h1 {
  font-size: 26px;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.5px;
  margin: 0;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav {
  display: flex;
  gap: 40px;
  flex: 1;
  list-style: none;
}

.nav-link {
  text-decoration: none;
  color: var(--text-dark);
  font-size: 15px;
  font-weight: 500;
  transition: all 0.3s ease;
  white-space: nowrap;
  position: relative;
}

.nav-link::after {
  /* Added underline animation on hover */
  content: "";
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: width 0.3s ease;
}

.nav-link:hover {
  color: var(--primary);
}

.nav-link:hover::after {
  width: 100%;
}

.header-btn {
  white-space: nowrap;
}

/* ==================== BUTTONS ==================== */
.btn {
  padding: 10px 24px;
  border: none;
  border-radius: 8px;
  /* Increased border radius for modern look */
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
  display: inline-block;
  white-space: nowrap;
  text-align: center;
}

.btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(14, 165, 233, 0.3);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
}

.btn-primary:hover {
  background: linear-gradient(135deg, var(--primary-dark) 0%, #0c5aa6 100%);
}

.btn-secondary {
  background: linear-gradient(135deg, var(--secondary) 0%, #0891b2 100%);
  color: white;
}

.btn-secondary:hover {
  background: linear-gradient(135deg, #0891b2 0%, #0d7a8c 100%);
}

.btn-small {
  padding: 8px 16px;
  font-size: 13px;
  border-radius: 6px;
}

.btn-large {
  /* Added large button variant */
  padding: 14px 32px;
  font-size: 16px;
  margin-top: 20px;
}

/* ==================== HERO SECTION ==================== */
.hero {
  background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
  /* Enhanced gradient for modern feel */
  padding: 100px 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  /* Added decorative background elements */
  content: "";
  position: absolute;
  top: -50%;
  right: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(14, 165, 233, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero::after {
  content: "";
  position: absolute;
  bottom: -30%;
  left: -5%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(6, 182, 212, 0.08) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 48px;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  color: var(--primary-dark);
  letter-spacing: -0.5px;
}

.hero p {
  font-size: 18px;
  color: var(--text-light);
  line-height: 1.7;
}

/* ==================== FEATURED SECTION ==================== */
.featured {
  padding: 100px 0;
  background-color: var(--bg-white);
}

.newest {
  padding: 100px 0;
  background: linear-gradient(180deg, var(--bg-light) 0%, var(--bg-white) 100%);
  /* Added gradient background for visual interest */
}

.section-title {
  font-size: 36px;
  font-weight: 800;
  margin-bottom: 15px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  /* Gradient text for modern look */
  letter-spacing: -0.5px;
}

.section-description {
  font-size: 16px;
  color: var(--text-light);
  max-width: 700px;
  margin-bottom: 50px;
  line-height: 1.6;
}

/* ==================== PRODUCTS GRID ==================== */
.products-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.product-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  /* Reduced border thickness for cleaner look */
  border-radius: 16px;
  /* Increased border radius for modern appearance */
  overflow: hidden;
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  /* Smooth cubic-bezier transition */
  display: flex;
  flex-direction: column;
  height: 100%;
  box-shadow: 0 4px 15px rgba(14, 165, 233, 0.06);
}

.product-card:hover {
  border-color: var(--primary-light);
  box-shadow: 0 20px 40px rgba(14, 165, 233, 0.15);
  /* Enhanced shadow on hover */
  transform: translateY(-12px);
  /* Increased lift effect */
}

.product-image {
  position: relative;
  overflow: hidden;
  height: 250px;
  background: linear-gradient(135deg, #e0f2fe 0%, #bae6fd 100%);
}

.product-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  /* Smoother image zoom on hover */
}

.product-card:hover .product-image img {
  transform: scale(1.1);
  /* Increased scale for dramatic effect */
}

.product-info {
  padding: 28px;
  /* Increased padding for more breathing room */
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.product-info h3,
.product-info h4 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--text-dark);
  line-height: 1.4;
  min-height: 48px;
}

.product-actions {
  display: flex;
  gap: 10px;
  margin-bottom: 16px;
}

.product-actions .btn {
  flex: 1;
}

.product-price {
  font-size: 22px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  /* Gradient text for price */
  margin-bottom: 12px;
  margin-top: auto;
}

.link {
  color: var(--primary);
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
  transition: all 0.3s ease;
  display: inline-block;
  position: relative;
}

.link::after {
  /* Added animated underline */
  content: "";
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: width 0.3s ease;
}

.link:hover {
  color: var(--primary-dark);
}

.link:hover::after {
  width: 100%;
}

/* ==================== FOOTER ==================== */
.footer {
  background: linear-gradient(135deg, #1a2332 0%, #0f1823 100%);
  /* Gradient background for footer */
  color: white;
  padding: 60px 0 30px;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
  margin-bottom: 40px;
  border-bottom: 1px solid rgba(14, 165, 233, 0.15);
  padding-bottom: 40px;
}

.footer-section .footer-title {
  font-size: 13px;
  font-weight: 700;
  margin-bottom: 20px;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--primary-light);
  /* Lighter color for better contrast */
}

.footer-section p {
  font-size: 14px;
  color: rgba(255, 255, 255, 0.75);
  line-height: 1.6;
}

.footer-section ul {
  list-style: none;
}

.footer-section ul li {
  margin-bottom: 12px;
}

.footer-section a {
  color: rgba(255, 255, 255, 0.75);
  text-decoration: none;
  font-size: 14px;
  transition: all 0.3s ease;
  position: relative;
}

.footer-section a::after {
  /* Added underline animation for footer links */
  content: "";
  position: absolute;
  bottom: -3px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--primary-light);
  transition: width 0.3s ease;
}

.footer-section a:hover {
  color: var(--primary-light);
}

.footer-section a:hover::after {
  width: 100%;
}

.footer-bottom {
  text-align: center;
}

.footer-bottom p {
  font-size: 14px;
  color: rgba(255, 255, 255, 0.6);
}

/* ==================== BREADCRUMB ==================== */
.breadcrumb {
  background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
  padding: 40px 0;
  border-bottom: 1px solid var(--border);
}

.breadcrumb .container {
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
}

.breadcrumb-nav a {
  color: var(--primary);
  text-decoration: none;
  transition: color 0.3s ease;
}

.breadcrumb-nav a:hover {
  color: var(--primary-dark);
}

.breadcrumb-nav span {
  color: var(--text-light);
}

.breadcrumb h1 {
  font-size: 32px;
  font-weight: 800;
  color: var(--primary-dark);
}

.breadcrumb p {
  font-size: 16px;
  color: var(--text-light);
}

/* ==================== FILTERS SECTION ==================== */
.filters-section {
  padding: 40px 0;
  border-bottom: 1px solid var(--border);
}

.filters {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 10px 20px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-white);
  color: var(--text-dark);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
}

.filter-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.filter-btn.active {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
  border-color: var(--primary);
}

/* .product-card sets display:flex, which would otherwise override the hidden attribute */
.product-card[hidden] {
  display: none;
}

/* ==================== SOLUTIONS LIST ==================== */
.solutions-list {
  padding: 60px 0;
}

.badge {
  position: absolute;
  top: 12px;
  right: 12px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  color: white;
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.description {
  font-size: 14px;
  color: var(--text-light);
  line-height: 1.5;
  margin-bottom: 16px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.product-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
}

.category {
  display: inline-block;
  background: var(--bg-light);
  color: var(--primary);
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 600;
}

/* ==================== DETAIL PAGE HERO ==================== */
.detail-hero {
  padding: 60px 0;
  background: linear-gradient(180deg, var(--bg-light) 0%, var(--bg-white) 100%);
}

.detail-hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.detail-image {
  position: relative;
  overflow: hidden;
  border-radius: 16px;
  box-shadow: 0 20px 50px rgba(14, 165, 233, 0.15);
}

.detail-image img {
  width: 100%;
  height: auto;
  display: block;
  transition: transform 0.5s ease;
}

.detail-image:hover img {
  transform: scale(1.05);
}

.detail-category {
  display: inline-block;
  background: var(--bg-light);
  color: var(--primary);
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 12px;
}

.detail-info h1 {
  font-size: 42px;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  color: var(--primary-dark);
}

.detail-description {
  font-size: 16px;
  color: var(--text-light);
  line-height: 1.7;
  margin-bottom: 30px;
}

.detail-pricing {
  margin-bottom: 30px;
  padding-bottom: 30px;
  border-bottom: 1px solid var(--border);
}

.price-main {
  font-size: 32px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 8px;
}

.price-note {
  font-size: 14px;
  color: var(--text-light);
}

.detail-actions {
  display: flex;
  gap: 15px;
  flex-wrap: wrap;
}

/* ==================== DETAIL FEATURES ==================== */
.detail-features {
  padding: 80px 0;
  background: var(--bg-white);
}

.detail-features h2 {
  font-size: 36px;
  font-weight: 800;
  margin-bottom: 50px;
  color: var(--primary-dark);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.feature-card {
  background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
  padding: 30px;
  border-radius: 12px;
  text-align: center;
  transition: all 0.3s ease;
  border: 1px solid var(--border);
}

.feature-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 15px 40px rgba(14, 165, 233, 0.15);
}

.feature-icon {
  font-size: 40px;
  margin-bottom: 15px;
}

.feature-card h3 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-dark);
}

.feature-card p {
  font-size: 14px;
  color: var(--text-light);
  line-height: 1.6;
}

/* ==================== DETAIL SPECS ==================== */
.detail-specs {
  padding: 80px 0;
  background: linear-gradient(180deg, var(--bg-light) 0%, var(--bg-white) 100%);
}

.detail-specs h2 {
  font-size: 36px;
  font-weight: 800;
  margin-bottom: 50px;
  color: var(--primary-dark);
}

.specs-content {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
}

.spec-column h3 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 20px;
  color: var(--text-dark);
}

.spec-list {
  list-style: none;
}

.spec-list li {
  padding: 10px 0;
  padding-left: 25px;
  position: relative;
  color: var(--text-light);
  font-size: 14px;
  line-height: 1.6;
}

.spec-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--primary);
  font-weight: 700;
  font-size: 16px;
}

/* ==================== DETAIL CTA ==================== */
.detail-cta {
  padding: 80px 0;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
  text-align: center;
}

.detail-cta h2 {
  font-size: 36px;
  font-weight: 800;
  margin-bottom: 15px;
  color: white;
}

.detail-cta p {
  font-size: 18px;
  color: rgba(255, 255, 255, 0.9);
  margin-bottom: 35px;
}

.cta-actions {
  display: flex;
  gap: 15px;
  justify-content: center;
  flex-wrap: wrap;
}

.cta-actions .btn {
  min-width: 200px;
}

/* ==================== DEMO BUTTON & MODAL ==================== */
.demo-btn {
  position: absolute;
  bottom: 12px;
  right: 12px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  color: white;
  border: none;
  padding: 10px 16px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  z-index: 10;
  box-shadow: 0 4px 12px rgba(14, 165, 233, 0.3);
}

.demo-btn:hover {
  transform: scale(1.05);
  box-shadow: 0 6px 16px rgba(14, 165, 233, 0.4);
}

.demo-btn span {
  display: flex;
  align-items: center;
  gap: 6px;
}

.demo-btn-large {
  padding: 12px 20px;
  font-size: 14px;
  bottom: 20px;
  right: 20px;
}

/* demo modal styling */
.demo-modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.7);
  z-index: 1000;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.demo-modal.active {
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 1;
}

.demo-modal-content {
  background: white;
  border-radius: 16px;
  padding: 30px;
  max-width: 900px;
  width: 90%;
  max-height: 85vh;
  overflow-y: auto;
  position: relative;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.demo-modal-close {
  position: absolute;
  top: 15px;
  right: 15px;
  background: none;
  border: none;
  font-size: 32px;
  color: var(--text-dark);
  cursor: pointer;
  transition: color 0.3s ease;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.demo-modal-close:hover {
  color: var(--primary);
}

#demoTitle {
  font-size: 28px;
  font-weight: 800;
  color: var(--primary-dark);
  margin-bottom: 25px;
}

.demo-gallery {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.demo-image-container {
  position: relative;
  overflow: hidden;
  border-radius: 12px;
  background: var(--bg-light);
}

.demo-image-container img {
  width: 100%;
  height: auto;
  display: block;
}

.demo-thumbnails {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.demo-thumbnail {
  border: 2px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  cursor: pointer;
  background: none;
  padding: 0;
  transition: all 0.3s ease;
}

.demo-thumbnail:hover {
  border-color: var(--primary);
}

.demo-thumbnail.active {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.2);
}

.demo-thumbnail img {
  width: 100%;
  height: 80px;
  object-fit: cover;
  display: block;
}

/* ==================== ORDER SUMMARY (dùng chung cho checkout / đặt dịch vụ / khóa học) ==================== */
.summary-row {
  display: flex;
  justify-content: space-between;
  margin-bottom: 15px;
  font-size: 14px;
}

.summary-divider {
  height: 1px;
  background: var(--border);
  margin: 20px 0;
}

.total-row {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary-dark);
}

.discount-text {
  color: #10b981;
}

/* ==================== CHECKOUT PAGE ==================== */
.checkout-section {
  padding: 60px 0;
  background: var(--bg-white);
  min-height: calc(100vh - 300px);
}

.checkout-layout {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 40px;
}

.checkout-form-wrapper {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 30px;
}

.checkout-step {
  display: none;
}

.checkout-step.active {
  display: block;
}

.step-title {
  font-size: 24px;
  font-weight: 800;
  margin-bottom: 30px;
  color: var(--text-dark);
}

.checkout-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.form-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 20px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.form-group label {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-dark);
}

.form-group input,
.form-group select {
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  transition: all 0.3s ease;
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.1);
}

.payment-methods {
  display: flex;
  flex-direction: column;
  gap: 15px;
  margin-bottom: 30px;
}

.payment-option {
  display: flex;
  align-items: center;
  padding: 20px;
  border: 2px solid var(--border);
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.3s ease;
}

.payment-option:hover {
  border-color: var(--primary-light);
}

.payment-option.active {
  border-color: var(--primary);
  background: var(--bg-light);
}

.payment-option input[type="radio"] {
  margin-right: 15px;
}

.payment-content {
  display: flex;
  align-items: center;
  gap: 15px;
}

.payment-icon {
  font-size: 32px;
}

.payment-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 4px;
}

.payment-desc {
  font-size: 13px;
  color: var(--text-light);
}

.payment-form {
  margin-top: 30px;
  padding-top: 30px;
  border-top: 1px solid var(--border);
}

.payment-note {
  font-size: 14px;
  color: var(--text-light);
}

.checkout-alert {
  margin-bottom: 20px;
  padding: 15px;
  border: 1px solid #fcc;
  border-radius: 8px;
  background: #fee;
  color: #c33;
}

.order-review {
  background: var(--bg-light);
  padding: 25px;
  border-radius: 12px;
}

.review-item {
  display: flex;
  justify-content: space-between;
  padding: 15px 0;
  border-bottom: 1px solid var(--border);
}

.review-divider {
  height: 1px;
  background: var(--border);
  margin: 15px 0;
}

.review-row {
  display: flex;
  justify-content: space-between;
  padding: 10px 0;
  font-size: 14px;
}

.review-row.highlight {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary-dark);
  margin-top: 10px;
}

.checkout-navigation {
  display: flex;
  justify-content: space-between;
  margin-top: 30px;
  padding-top: 30px;
  border-top: 1px solid var(--border);
}

.checkout-summary {
  position: sticky;
  top: 90px;
  height: fit-content;
}

.summary-card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 30px;
}

.summary-card h3 {
  font-size: 24px;
  font-weight: 800;
  margin-bottom: 25px;
  color: var(--text-dark);
}

.summary-item {
  display: grid;
  grid-template-columns: 80px 1fr auto;
  gap: 15px;
  padding: 15px 0;
  border-bottom: 1px solid var(--border);
}

.summary-item-image img {
  width: 80px;
  height: 80px;
  object-fit: cover;
  border-radius: 8px;
}

.summary-item-name {
  font-size: 14px;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 4px;
}

.summary-item-desc {
  font-size: 12px;
  color: var(--text-light);
}

.summary-item-price {
  font-size: 16px;
  font-weight: 700;
  color: var(--primary-dark);
}

.promo-section {
  margin: 20px 0;
}

.promo-section label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text-dark);
}

.promo-input {
  display: flex;
  gap: 10px;
}

.promo-field {
  flex: 1;
  padding: 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
}

.promo-btn {
  padding: 10px 20px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
}

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

.promo-hint {
  font-size: 12px;
  color: var(--text-light);
  margin-top: 8px;
}

.summary-breakdown {
  margin-top: 20px;
}

.breakdown-row {
  display: flex;
  justify-content: space-between;
  padding: 10px 0;
  font-size: 14px;
}

.breakdown-row.total {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary-dark);
  margin-top: 10px;
  padding-top: 15px;
  border-top: 2px solid var(--border);
}

.security-note {
  margin-top: 20px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  font-size: 13px;
  color: var(--text-light);
  text-align: center;
}

@media (max-width: 768px) {
  .checkout-layout {
    grid-template-columns: 1fr;
  }

  .checkout-summary {
    position: static;
  }

  .products-grid {
    grid-template-columns: 1fr;
  }

  .features-grid,
  .specs-content {
    grid-template-columns: 1fr;
  }
}

/* ==================== BẢN HTML TĨNH: BỔ SUNG DÙNG CHUNG ==================== */
/* Phần dưới đây không có trong public/css/app.css: menu cho màn hình nhỏ và vài khối dùng chung. */

.nav-link.active {
  color: var(--primary);
}

.nav-link.active::after {
  width: 100%;
}

.header-btn {
  display: flex;
  gap: 10px;
  align-items: center;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  width: 42px;
  height: 42px;
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  flex-shrink: 0;
}

.nav-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--primary-dark);
  border-radius: 2px;
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.header.nav-open .nav-toggle span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.header.nav-open .nav-toggle span:nth-child(2) { opacity: 0; }
.header.nav-open .nav-toggle span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

button.btn {
  font-family: inherit;
}

.btn[disabled] {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.btn-block {
  display: block;
  width: 100%;
  text-align: center;
}

.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-light);
}

.products-grid > .empty-state {
  grid-column: 1 / -1;
}

.not-found {
  padding: 100px 0;
  text-align: center;
  background: var(--bg-light);
}

.not-found h1 {
  font-size: 72px;
  font-weight: 800;
  color: var(--primary);
  line-height: 1;
  margin-bottom: 15px;
}

.not-found p {
  font-size: 18px;
  color: var(--text-light);
  margin-bottom: 25px;
}

.price {
  font-weight: 700;
  color: var(--primary-dark);
}

@media (max-width: 1100px) {
  .header-content {
    gap: 20px;
  }

  .nav {
    gap: 22px;
  }
}

@media (max-width: 960px) {
  .header .container {
    position: relative;
  }

  .header-content {
    height: 64px;
  }

  .logo-image {
    height: 42px;
  }

  .nav-toggle {
    display: flex;
    order: 3;
  }

  .nav,
  .header-btn {
    display: none;
  }

  .header.nav-open .nav,
  .header.nav-open .header-btn {
    display: flex;
  }

  .header.nav-open .header-content {
    flex-wrap: wrap;
    height: auto;
    min-height: 64px;
    padding: 11px 0 16px;
    row-gap: 12px;
  }

  .header.nav-open .nav {
    order: 4;
    flex-basis: 100%;
    flex-direction: column;
    gap: 0;
  }

  .header.nav-open .nav-link {
    padding: 12px 4px;
    border-bottom: 1px solid var(--border);
  }

  .header.nav-open .nav-link::after {
    display: none;
  }

  .header.nav-open .header-btn {
    order: 5;
    flex-basis: 100%;
    flex-wrap: wrap;
  }
}

@media (max-width: 768px) {
  .hero {
    padding: 70px 0;
  }

  .hero h1 {
    font-size: 34px;
  }

  .featured,
  .newest {
    padding: 60px 0;
  }

  .section-title {
    font-size: 28px;
  }

  .detail-hero-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .detail-info h1 {
    font-size: 32px;
  }

  .footer-content {
    grid-template-columns: 1fr 1fr;
  }

  .demo-thumbnails {
    grid-template-columns: repeat(3, 1fr);
  }

  .checkout-navigation {
    gap: 10px;
  }
}

@media (max-width: 480px) {
  .footer-content {
    grid-template-columns: 1fr;
  }

  .product-actions {
    flex-direction: column;
  }

  .breadcrumb h1 {
    font-size: 26px;
  }
}

/* Ẩn khỏi màn hình nhưng vẫn đọc được bằng trình đọc màn hình */
.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Footer 5 cột (thêm cột "Liên hệ": Facebook + email) */
.footer-contact li {
  display: flex;
  align-items: center;
  gap: 8px;
}

@media (min-width: 1025px) {
  .footer-content {
    grid-template-columns: 1.4fr repeat(4, 1fr);
    gap: 32px;
  }
}

@media (min-width: 769px) and (max-width: 1024px) {
  .footer-content .footer-section:first-child {
    grid-column: 1 / -1;
  }
}