:root {
  --primary: #0D1B2A;
  --secondary: #1B263B;
  --accent: #FFA500;
  --highlight: #1ABC9C;
  --text: #ECF0F1;
  --gold: #FFD700;
  --silver: #C0C0C0;
}

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

body {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: var(--text);
  font-family: 'Open Sans', sans-serif;
  line-height: 1.6;
  padding: 0;
  margin: 0;
}

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

.header {
  background: rgba(13, 27, 42, 0.9);
  padding: 20px 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  backdrop-filter: blur(10px);
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 20px;
}

.logo {
  font-family: 'Roboto', sans-serif;
  font-size: 24px;
  font-weight: 700;
  color: var(--gold);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo::before {
  content: "";
  display: inline-block;
  width: 30px;
  height: 30px;
  background: url('https://images.gptkong.com/demo/sample1.png') center/cover;
  border-radius: 50%;
}

.nav-menu {
  display: flex;
  gap: 25px;
}

.nav-item {
  list-style: none;
}

.nav-link {
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
  padding: 8px 12px;
  border-radius: 5px;
  transition: all 0.3s ease;
  position: relative;
}

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

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

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

.hero {
  padding: 60px 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url('https://images.gptkong.com/demo/sample2.png') center/cover;
  opacity: 0.1;
  z-index: -1;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 20px;
  color: var(--gold);
  text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.hero p {
  font-size: 1.2rem;
  max-width: 800px;
  margin: 0 auto 30px;
}

.notice {
  background: rgba(255, 215, 0, 0.1);
  border: 1px solid var(--gold);
  border-radius: 8px;
  padding: 15px;
  margin: 30px auto;
  max-width: 800px;
  text-align: center;
  font-weight: 600;
  color: var(--gold);
}

.content {
  display: grid;
  grid-template-columns: 250px 1fr;
  gap: 30px;
  margin-top: 40px;
}

.sidebar {
  background: rgba(27, 38, 59, 0.7);
  border-radius: 10px;
  padding: 20px;
  height: fit-content;
  position: sticky;
  top: 100px;
}

.sidebar-title {
  font-size: 1.2rem;
  margin-bottom: 20px;
  color: var(--gold);
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(255, 215, 0, 0.3);
}

.sidebar-menu {
  list-style: none;
}

.sidebar-item {
  margin-bottom: 15px;
}

.sidebar-link {
  color: var(--text);
  text-decoration: none;
  display: block;
  padding: 8px 12px;
  border-radius: 5px;
  transition: all 0.3s ease;
}

.sidebar-link:hover {
  background: rgba(255, 165, 0, 0.2);
  color: var(--accent);
}

.main-content {
  background: rgba(27, 38, 59, 0.7);
  border-radius: 10px;
  padding: 30px;
}

article {
  max-width: 100%;
}

article h2 {
  font-size: 2rem;
  color: var(--gold);
  margin-bottom: 25px;
  position: relative;
  padding-bottom: 10px;
}

article h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100px;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), transparent);
}

article h3 {
  font-size: 1.5rem;
  color: var(--highlight);
  margin: 30px 0 15px;
}

article p {
  margin-bottom: 20px;
  font-size: 1.1rem;
}

pre {
  background: #1E2A3A;
  border-radius: 8px;
  padding: 20px;
  margin: 25px 0;
  overflow-x: auto;
  box-shadow: inset 0 0 10px rgba(0,0,0,0.5);
  position: relative;
}

pre::before {
  content: 'CSS';
  position: absolute;
  top: 0;
  right: 0;
  background: var(--accent);
  color: var(--primary);
  padding: 2px 10px;
  border-radius: 0 0 0 5px;
  font-size: 0.8rem;
  font-weight: bold;
}

code {
  font-family: 'Courier New', monospace;
  color: #F8F8F2;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
  margin: 30px 0;
}

.card {
  background: #2C3E50;
  border-radius: 10px;
  padding: 20px;
  transition: all 0.3s ease;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
  position: relative;
  overflow: hidden;
}

.card::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 5px;
  background: linear-gradient(90deg, var(--highlight), var(--accent));
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.card-img {
  width: 100%;
  height: 180px;
  object-fit: cover;
  border-radius: 5px;
  margin-bottom: 15px;
}

.card-title {
  font-size: 1.2rem;
  margin-bottom: 10px;
  color: var(--gold);
}

.card-desc {
  font-size: 0.9rem;
  color: rgba(236, 240, 241, 0.8);
}

.footer {
  background: var(--primary);
  padding: 30px 0;
  margin-top: 60px;
  text-align: center;
}

.footer-content {
  max-width: 800px;
  margin: 0 auto;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 20px;
  margin-bottom: 20px;
}

.footer-link {
  color: var(--text);
  text-decoration: none;
  transition: color 0.3s ease;
}

.footer-link:hover {
  color: var(--accent);
}

.copyright {
  font-size: 0.9rem;
  color: rgba(236, 240, 241, 0.7);
}

@media (max-width: 992px) {
  .content {
    grid-template-columns: 1fr;
  }
  
  .sidebar {
    position: static;
    margin-bottom: 30px;
  }
}

@media (max-width: 768px) {
  .navbar {
    flex-direction: column;
    gap: 15px;
  }
  
  .nav-menu {
    flex-wrap: wrap;
    justify-content: center;
  }
  
  .hero h1 {
    font-size: 2.2rem;
  }
  
  article h2 {
    font-size: 1.8rem;
  }
  
  article h3 {
    font-size: 1.3rem;
  }
}

@media (max-width: 576px) {
  .card-grid {
    grid-template-columns: 1fr;
  }
  
  .hero h1 {
    font-size: 1.8rem;
  }
  
  .hero p {
    font-size: 1rem;
  }
  
  article h2 {
    font-size: 1.5rem;
  }
}

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

.animate {
  animation: fadeIn 0.6s ease-out forwards;
}

.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }
.delay-3 { animation-delay: 0.6s; }

/* Utility Classes */
.text-center { text-align: center; }
.mt-20 { margin-top: 20px; }
.mb-20 { margin-bottom: 20px; }
.p-20 { padding: 20px; }

/* Tab Styles */
.tab-container {
  margin: 30px 0;
}

.tab-header {
  display: flex;
  border-bottom: 2px solid var(--highlight);
}

.tab-btn {
  padding: 12px 24px;
  background: transparent;
  border: none;
  color: var(--text);
  font-weight: 600;
  cursor: pointer;
  position: relative;
  transition: all 0.3s ease;
}

.tab-btn.active {
  color: var(--accent);
}

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

.tab-btn.active::after {
  width: 100%;
}

.tab-content {
  display: none;
  padding: 20px;
  background: rgba(44, 62, 80, 0.5);
  border-radius: 0 0 8px 8px;
  animation: fadeIn 0.5s ease;
}

.tab-content.active {
  display: block;
}

/* Button Styles */
.btn {
  display: inline-block;
  padding: 12px 24px;
  border-radius: 5px;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
}

.btn-primary {
  background: linear-gradient(45deg, var(--accent), #FF8C00);
  color: var(--primary);
}

.btn-primary:hover {
  background: linear-gradient(45deg, #FF8C00, var(--accent));
  box-shadow: 0 4px 12px rgba(255, 165, 0, 0.3);
}

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

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

/* Chart Styles */
.chart-container {
  height: 300px;
  background: rgba(26, 188, 156, 0.1);
  border-radius: 8px;
  margin: 30px 0;
  padding: 20px;
  position: relative;
  overflow: hidden;
}

.chart-container::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url('https://images.gptkong.com/demo/sample3.png') center/cover;
  opacity: 0.05;
  z-index: 0;
}

.chart-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--highlight);
  font-weight: 600;
  position: relative;
  z-index: 1;
}

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

.tooltip .tooltip-text {
  visibility: hidden;
  width: 200px;
  background: var(--secondary);
  color: var(--text);
  text-align: center;
  border-radius: 6px;
  padding: 10px;
  position: absolute;
  z-index: 1;
  bottom: 125%;
  left: 50%;
  transform: translateX(-50%);
  opacity: 0;
  transition: opacity 0.3s;
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.tooltip:hover .tooltip-text {
  visibility: visible;
  opacity: 1;
}

/* Accordion Styles */
.accordion {
  margin: 20px 0;
}

.accordion-item {
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 5px;
  margin-bottom: 10px;
  overflow: hidden;
}

.accordion-header {
  padding: 15px 20px;
  background: rgba(44, 62, 80, 0.5);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background 0.3s ease;
}

.accordion-header:hover {
  background: rgba(44, 62, 80, 0.7);
}

.accordion-content {
  padding: 0;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
}

.accordion-item.active .accordion-content {
  padding: 15px 20px;
  max-height: 500px;
}

.accordion-icon {
  transition: transform 0.3s ease;
}

.accordion-item.active .accordion-icon {
  transform: rotate(180deg);
}

/* Badge Styles */
.badge {
  display: inline-block;
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-left: 8px;
}

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

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

/* Progress Bar Styles */
.progress-container {
  width: 100%;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 5px;
  margin: 15px 0;
  overflow: hidden;
}

.progress-bar {
  height: 10px;
  background: linear-gradient(90deg, var(--highlight), var(--accent));
  border-radius: 5px;
  transition: width 0.5s ease;
}

/* Floating Action Button */
.fab {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 60px;
  height: 60px;
  background: var(--accent);
  color: var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(255, 165, 0, 0.3);
  cursor: pointer;
  transition: all 0.3s ease;
  z-index: 99;
}

.fab:hover {
  transform: scale(1.1);
  box-shadow: 0 6px 16px rgba(255, 165, 0, 0.4);
}

/* Pulse Animation */
@keyframes pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.05); }
  100% { transform: scale(1); }
}

.pulse {
  animation: pulse 2s infinite;
}

/* Grid System */
.grid {
  display: grid;
  gap: 20px;
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

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

@media (max-width: 768px) {
  .grid-2, .grid-3 {
    grid-template-columns: 1fr;
  }
}

/* Image Gallery */
.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 15px;
  margin: 30px 0;
}

.gallery-item {
  border-radius: 8px;
  overflow: hidden;
  position: relative;
  transition: transform 0.3s ease;
}

.gallery-item:hover {
  transform: scale(1.03);
}

.gallery-img {
  width: 100%;
  height: 150px;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.gallery-item:hover .gallery-img {
  transform: scale(1.1);
}

.gallery-caption {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  background: rgba(0, 0, 0, 0.7);
  color: white;
  padding: 10px;
  transform: translateY(100%);
  transition: transform 0.3s ease;
}

.gallery-item:hover .gallery-caption {
  transform: translateY(0);
}

/* Timeline */
.timeline {
  position: relative;
  max-width: 800px;
  margin: 30px auto;
}

.timeline::before {
  content: '';
  position: absolute;
  width: 2px;
  background: var(--highlight);
  top: 0;
  bottom: 0;
  left: 50%;
  margin-left: -1px;
}

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

.timeline-item:nth-child(odd) {
  left: 0;
}

.timeline-item:nth-child(even) {
  left: 50%;
}

.timeline-content {
  padding: 20px;
  background: rgba(44, 62, 80, 0.7);
  border-radius: 8px;
  position: relative;
}

.timeline-item:nth-child(odd) .timeline-content::after {
  content: '';
  position: absolute;
  border-style: solid;
  border-width: 10px 0 10px 10px;
  border-color: transparent transparent transparent rgba(44, 62, 80, 0.7);
  right: -10px;
  top: 20px;
}

.timeline-item:nth-child(even) .timeline-content::after {
  content: '';
  position: absolute;
  border-style: solid;
  border-width: 10px 10px 10px 0;
  border-color: transparent rgba(44, 62, 80, 0.7) transparent transparent;
  left: -10px;
  top: 20px;
}

.timeline-date {
  font-weight: bold;
  color: var(--accent);
  margin-bottom: 10px;
}

@media (max-width: 768px) {
  .timeline::before {
    left: 31px;
  }
  
  .timeline-item {
    width: 100%;
    padding-left: 70px;
    padding-right: 25px;
  }
  
  .timeline-item:nth-child(even) {
    left: 0;
  }
  
  .timeline-item:nth-child(odd) .timeline-content::after,
  .timeline-item:nth-child(even) .timeline-content::after {
    left: 60px;
    border-width: 10px 10px 10px 0;
    border-color: transparent rgba(44, 62, 80, 0.7) transparent transparent;
    right: auto;
  }
}