:root {
  --primary: #1E3A8A;
  --secondary: #3B82F6;
  --accent: #F97316;
  --light: #F3F4F6;
  --dark: #111827;
  --text: #374151;
}

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

body {
  font-family: 'Roboto', 'Segoe UI', sans-serif;
  line-height: 1.6;
  color: var(--text);
  background: linear-gradient(135deg, #f5f7fa 0%, #e4e8f0 100%);
  min-height: 100%;
}

header {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
  padding: 2rem 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

header::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url('https://images.gptkong.com/demo/sample1.png') center/cover no-repeat;
  opacity: 0.1;
  z-index: 0;
}

.header-content {
  position: relative;
  z-index: 1;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.subtitle {
  font-size: 1.2rem;
  opacity: 0.9;
  max-width: 800px;
  margin: 0 auto 2rem;
}

.navbar {
  background-color: rgba(30, 58, 138, 0.95);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  backdrop-filter: blur(8px);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: white;
  text-decoration: none;
}

.nav-menu {
  display: flex;
  list-style: none;
}

.nav-item {
  margin-left: 2rem;
  position: relative;
}

.nav-link {
  color: white;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s ease;
  padding: 0.5rem 0;
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--accent);
  transition: width 0.3s ease;
}

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

.nav-link:hover {
  color: #FB923C;
}

.main-container {
  max-width: 1200px;
  margin: 3rem auto;
  padding: 0 2rem;
}

article {
  background: white;
  border-radius: 12px;
  box-shadow: 0 8px 30px rgba(0,0,0,0.08);
  padding: 3rem;
  margin-bottom: 3rem;
}

h2 {
  font-size: 2rem;
  color: var(--primary);
  margin-bottom: 1.5rem;
  position: relative;
  padding-bottom: 0.5rem;
}

h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--secondary));
}

h3 {
  font-size: 1.5rem;
  color: var(--secondary);
  margin: 2rem 0 1rem;
}

p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
  line-height: 1.7;
}

.code-container {
  background: #1e1e1e;
  border-radius: 8px;
  padding: 1.5rem;
  margin: 2rem 0;
  overflow-x: auto;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

pre {
  margin: 0;
  font-family: 'Consolas', 'Monaco', monospace;
  font-size: 0.95rem;
  line-height: 1.5;
  color: #d4d4d4;
}

code {
  font-family: inherit;
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin: 2rem 0;
}

.image-card {
  background: white;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.image-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

.image-card img {
  width: 100%;
  height: 200px;
  object-fit: cover;
  display: block;
}

.image-caption {
  padding: 1rem;
  background: white;
}

.image-caption h4 {
  color: var(--primary);
  margin-bottom: 0.5rem;
}

.image-caption p {
  font-size: 0.95rem;
  color: var(--text);
  opacity: 0.8;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 2rem 0;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

thead {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
}

th {
  padding: 1rem;
  text-align: left;
  font-weight: 500;
}

tbody tr:nth-child(even) {
  background-color: #f8fafc;
}

td {
  padding: 1rem;
  border-bottom: 1px solid #e2e8f0;
}

footer {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
  padding: 3rem 0;
  text-align: center;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.footer-notice {
  font-size: 0.9rem;
  opacity: 0.8;
  margin-top: 2rem;
}

@media (max-width: 768px) {
  .nav-container {
    flex-direction: column;
    padding: 1rem;
  }
  
  .nav-menu {
    margin-top: 1rem;
    flex-direction: column;
    align-items: center;
  }
  
  .nav-item {
    margin: 0.5rem 0;
  }
  
  article {
    padding: 2rem 1.5rem;
  }
  
  .image-grid {
    grid-template-columns: 1fr;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.7rem;
  }
  
  h3 {
    font-size: 1.3rem;
  }
}

/* Animation */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

article {
  animation: fadeIn 0.6s ease-out;
}

/* Floating elements */
.floating {
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-15px);
  }
}

/* Decorative elements */
.decorative-line {
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  margin: 2rem 0;
  opacity: 0.5;
}

/* Tooltip */
.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted var(--secondary);
  cursor: help;
}

.tooltip .tooltiptext {
  visibility: hidden;
  width: 200px;
  background-color: var(--dark);
  color: white;
  text-align: center;
  border-radius: 6px;
  padding: 0.5rem;
  position: absolute;
  z-index: 1;
  bottom: 125%;
  left: 50%;
  transform: translateX(-50%);
  opacity: 0;
  transition: opacity 0.3s;
}

.tooltip:hover .tooltiptext {
  visibility: visible;
  opacity: 1;
}

/* Accordion */
.accordion {
  background-color: white;
  color: var(--text);
  cursor: pointer;
  padding: 1rem;
  width: 100%;
  border: none;
  text-align: left;
  outline: none;
  font-size: 1rem;
  transition: 0.4s;
  margin: 0.5rem 0;
  border-radius: 6px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.accordion:after {
  content: '+';
  font-size: 1.2rem;
  color: var(--primary);
  font-weight: bold;
  transition: transform 0.3s;
}

.active:after {
  content: '-';
}

.panel {
  padding: 0 1rem;
  background-color: white;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out;
  margin-bottom: 1rem;
  border-radius: 0 0 6px 6px;
}

/* Button styles */
.btn {
  display: inline-block;
  background: linear-gradient(45deg, var(--accent), #FB923C);
  color: white;
  padding: 0.8rem 1.5rem;
  border-radius: 30px;
  text-decoration: none;
  font-weight: 500;
  transition: all 0.3s ease;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
  border: none;
  cursor: pointer;
  margin: 0.5rem 0;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 12px rgba(0,0,0,0.15);
  background: linear-gradient(45deg, #FB923C, var(--accent));
}

.btn-secondary {
  background: transparent;
  border: 2px solid var(--secondary);
  color: var(--secondary);
}

.btn-secondary:hover {
  background: var(--secondary);
  color: white;
}

/* Card styles */
.card {
  background: white;
  border-radius: 10px;
  padding: 1.5rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  margin: 1rem 0;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.12);
}

.card-title {
  color: var(--primary);
  margin-bottom: 0.5rem;
}

/* Highlight box */
.highlight {
  background: linear-gradient(90deg, rgba(59,130,246,0.1), rgba(59,130,246,0.05));
  border-left: 4px solid var(--secondary);
  padding: 1.5rem;
  margin: 2rem 0;
  border-radius: 0 6px 6px 0;
}

/* Progress bar */
.progress-container {
  width: 100%;
  background-color: #e2e8f0;
  border-radius: 10px;
  margin: 1rem 0;
}

.progress-bar {
  height: 10px;
  border-radius: 10px;
  background: linear-gradient(90deg, var(--secondary), var(--primary));
  width: 0;
  transition: width 1s ease-in-out;
}

/* Tabs */
.tab {
  overflow: hidden;
  border-bottom: 1px solid #e2e8f0;
  margin: 1rem 0;
}

.tab button {
  background-color: inherit;
  float: left;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 0.8rem 1.2rem;
  transition: 0.3s;
  font-size: 1rem;
  color: var(--text);
  position: relative;
}

.tab button:after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--secondary);
  transition: width 0.3s ease;
}

.tab button:hover:after {
  width: 100%;
}

.tab button.active {
  color: var(--primary);
  font-weight: 500;
}

.tab button.active:after {
  width: 100%;
}

.tabcontent {
  display: none;
  padding: 1rem 0;
  animation: fadeIn 0.5s ease;
}

/* Responsive iframe */
.responsive-iframe {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  margin: 1.5rem 0;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.responsive-iframe iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}

/* Floating action button */
.fab {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 60px;
  height: 60px;
  background: linear-gradient(45deg, var(--accent), #FB923C);
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  cursor: pointer;
  transition: all 0.3s ease;
  z-index: 99;
  border: none;
}

.fab:hover {
  transform: scale(1.1);
  box-shadow: 0 6px 16px rgba(0,0,0,0.3);
}

/* Notification */
.notification {
  position: fixed;
  bottom: 1rem;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary);
  color: white;
  padding: 1rem 2rem;
  border-radius: 30px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  z-index: 100;
  display: flex;
  align-items: center;
  animation: slideUp 0.5s ease;
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateX(-50%) translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
  }
}

.notification-close {
  margin-left: 1rem;
  cursor: pointer;
  opacity: 0.8;
}

.notification-close:hover {
  opacity: 1;
}

/* Breadcrumb */
.breadcrumb {
  padding: 1rem 0;
  font-size: 0.9rem;
  color: var(--text);
}

.breadcrumb a {
  color: var(--secondary);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

.breadcrumb-separator {
  margin: 0 0.5rem;
  color: #94a3b8;
}

/* Pagination */
.pagination {
  display: flex;
  justify-content: center;
  margin: 2rem 0;
}

.pagination a {
  color: var(--primary);
  padding: 0.5rem 1rem;
  text-decoration: none;
  border: 1px solid #e2e8f0;
  margin: 0 0.25rem;
  border-radius: 4px;
  transition: all 0.3s ease;
}

.pagination a.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.pagination a:hover:not(.active) {
  background: #f1f5f9;
}

/* Badge */
.badge {
  display: inline-block;
  padding: 0.25rem 0.5rem;
  font-size: 0.75rem;
  font-weight: 600;
  line-height: 1;
  text-align: center;
  white-space: nowrap;
  vertical-align: baseline;
  border-radius: 10px;
  background: var(--secondary);
  color: white;
}

.badge-primary {
  background: var(--primary);
}

.badge-accent {
  background: var(--accent);
}

/* Alert */
.alert {
  padding: 1rem;
  margin: 1rem 0;
  border-radius: 6px;
  position: relative;
}

.alert-success {
  background-color: #f0fdf4;
  border-left: 4px solid #10b981;
  color: #065f46;
}

.alert-info {
  background-color: #f0f9ff;
  border-left: 4px solid #0ea5e9;
  color: #075985;
}

.alert-warning {
  background-color: #fefce8;
  border-left: 4px solid #f59e0b;
  color: #92400e;
}

.alert-error {
  background-color: #fef2f2;
  border-left: 4px solid #ef4444;
  color: #991b1b;
}

/* Spinner */
.spinner {
  display: inline-block;
  width: 40px;
  height: 40px;
  border: 4px solid rgba(59, 130, 246, 0.2);
  border-radius: 50%;
  border-top-color: var(--secondary);
  animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Avatar */
.avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  object-fit: cover;
  display: inline-block;
  vertical-align: middle;
}

.avatar-lg {
  width: 60px;
  height: 60px;
}

.avatar-sm {
  width: 30px;
  height: 30px;
}

/* Divider */
.divider {
  display: flex;
  align-items: center;
  margin: 1.5rem 0;
}

.divider::before, .divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: #e2e8f0;
}

.divider-text {
  padding: 0 1rem;
  color: #94a3b8;
  font-size: 0.9rem;
}

/* Dropdown */
.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: white;
  min-width: 160px;
  box-shadow: 0 8px 16px rgba(0,0,0,0.1);
  z-index: 1;
  border-radius: 6px;
  overflow: hidden;
}

.dropdown:hover .dropdown-content {
  display: block;
  animation: fadeIn 0.3s ease;
}

.dropdown-item {
  color: var(--text);
  padding: 0.75rem 1rem;
  text-decoration: none;
  display: block;
  transition: background-color 0.3s;
}

.dropdown-item:hover {
  background-color: #f8fafc;
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto;
  background-color: rgba(0,0,0,0.5);
  animation: fadeIn 0.3s ease;
}

.modal-content {
  background-color: white;
  margin: 10% auto;
  padding: 2rem;
  border-radius: 8px;
  width: 80%;
  max-width: 800px;
  box-shadow: 0 8px 32px rgba(0,0,0,0.2);
  position: relative;
}

.close {
  position: absolute;
  top: 1rem;
  right: 1.5rem;
  font-size: 1.5rem;
  font-weight: bold;
  color: #94a3b8;
  cursor: pointer;
  transition: color 0.3s;
}

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

/* Timeline */
.timeline {
  position: relative;
  max-width: 800px;
  margin: 2rem auto;
}

.timeline::after {
  content: '';
  position: absolute;
  width: 2px;
  background-color: #e2e8f0;
  top: 0;
  bottom: 0;
  left: 50%;
  margin-left: -1px;
}

.timeline-item {
  padding: 10px 40px;
  position: relative;
  width: 50%;
  box-sizing: border-box;
}

.timeline-item::after {
  content: '';
  position: absolute;
  width: 20px;
  height: 20px;
  background-color: white;
  border: 4px solid var(--secondary);
  border-radius: 50%;
  top: 15px;
  z-index: 1;
}

.left {
  left: 0;
}

.right {
  left: 50%;
}

.right::after {
  left: -12px;
}

.left::after {
  right: -12px;
}

.timeline-content {
  padding: 1.5rem;
  background-color: white;
  border-radius: 6px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.timeline-date {
  font-weight: bold;
  color: var(--secondary);
  margin-bottom: 0.5rem;
}

/* Toolbar */
.toolbar {
  display: flex;
  background-color: white;
  padding: 0.75rem 1.5rem;
  border-radius: 6px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
  margin: 1rem 0;
}

.toolbar-group {
  display: flex;
  align-items: center;
  margin-right: 1.5rem;
}

.toolbar-group:last-child {
  margin-right: 0;
}

.toolbar-button {
  background: none;
  border: none;
  color: var(--text);
  cursor: pointer;
  padding: 0.5rem;
  margin: 0 0.25rem;
  border-radius: 4px;
  transition: all 0.3s;
}

.toolbar-button:hover {
  background-color: #f1f5f9;
  color: var(--primary);
}

.toolbar-separator {
  width: 1px;
  background-color: #e2e8f0;
  margin: 0 0.5rem;
}

/* Chip */
.chip {
  display: inline-flex;
  align-items: center;
  background-color: #f1f5f9;
  color: var(--text);
  padding: 0.25rem 0.75rem;
  border-radius: 16px;
  font-size: 0.85rem;
  margin: 0.25rem;
}

.chip-close {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 16px;
  height: 16px;
  background-color: #cbd5e1;
  color: white;
  border-radius: 50%;
  margin-left: 0.5rem;
  cursor: pointer;
  font-size: 0.7rem;
  transition: background-color 0.3s;
}

.chip-close:hover {
  background-color: #94a3b8;
}

/* Skeleton loading */
.skeleton {
  background-color: #e2e8f0;
  border-radius: 4px;
  animation: pulse 1.5s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

.skeleton-text {
  height: 1rem;
  margin-bottom: 0.5rem;
}

.skeleton-text:last-child {
  margin-bottom: 0;
  width: 80%;
}

.skeleton-circle {
  width: 40px;
  height: 40px;
  border-radius: 50%;
}

/* Custom scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: #f1f5f9;
}

::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}

/* Print styles */
@media print {
  body {
    background: white;
    color: black;
    font-size: 12pt;
  }
  
  .navbar, .fab, .notification {
    display: none;
  }
  
  article {
    box-shadow: none;
    padding: 0;
    margin: 0;
  }
  
  .code-container {
    page-break-inside: avoid;
  }
  
  a::after {
    content: " (" attr(href) ")";
    font-size: 0.8em;
    font-weight: normal;
  }
}