:root {
  --bg-color: #0f172a;
  --card-bg: #1e293b;
  --text-color: #f1f5f9;
  --text-muted: #94a3b8;
  --primary-color: #06b6d4; /* Cyan/Teal */
  --secondary-color: #3b82f6; /* Blue */
  --accent-color: #22d3ee;
  --border-color: #334155;
  --font-main: "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --max-width: 1200px;
}

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

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: var(--font-main);
  line-height: 1.6;
}

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

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

/* Layout Utilities */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

.section {
  padding: 60px 0;
}

/* Top CTA Bar */
.top-cta-bar {
  background: linear-gradient(
    90deg,
    var(--secondary-color),
    var(--primary-color)
  );
  color: #ffffff;
  text-align: center;
  padding: 10px 40px 10px 20px;
  font-weight: 600;
  font-size: 0.95rem;
  position: relative;
  z-index: 1001;
}

.top-cta-bar a {
  color: #ffffff;
  text-decoration: underline;
  margin-left: 10px;
  font-weight: 700;
}

.top-cta-bar a:hover {
  color: #e2e8f0;
}

.cta-close {
  position: absolute;
  right: 15px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  color: white;
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  opacity: 0.8;
  padding: 0 5px;
}

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

/* Header & Navigation */
header {
  background-color: rgba(15, 23, 42, 0.95);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 1000;
  backdrop-filter: blur(10px);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 80px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: bold;
  font-size: 1.2rem;
  color: var(--text-color);
}

.logo img {
  height: 50px;
  width: auto;
  border-radius: 8px;
}

nav ul {
  display: flex;
  list-style: none;
  gap: 25px;
}

nav a {
  color: var(--text-color);
  font-weight: 500;
}

nav a:hover,
nav a.active {
  color: var(--primary-color);
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 100px 20px;
  background: radial-gradient(circle at center, #1e293b 0%, #0f172a 70%);
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 20px;
  background: linear-gradient(
    to right,
    var(--primary-color),
    var(--secondary-color)
  );
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero .subtitle {
  font-size: 1.5rem;
  color: var(--text-muted);
  margin-bottom: 40px;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.btn {
  display: inline-block;
  padding: 12px 30px;
  background: linear-gradient(
    135deg,
    var(--secondary-color),
    var(--primary-color)
  );
  color: white;
  border-radius: 50px;
  font-weight: bold;
  font-size: 1.1rem;
  border: none;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(6, 182, 212, 0.3);
  color: white;
}

/* Cards Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin-top: 40px;
}

.card {
  background-color: var(--card-bg);
  padding: 30px;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  transition: transform 0.3s ease, border-color 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  border-color: var(--primary-color);
}

.card h3 {
  color: var(--primary-color);
  margin-bottom: 15px;
  font-size: 1.4rem;
}

.card p {
  color: var(--text-muted);
}

/* FAQ Section */
.faq-grid {
  max-width: 800px;
  margin: 0 auto;
}

details.faq-item {
  background-color: var(--bg-color);
  margin-bottom: 15px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  overflow: hidden;
  transition: border-color 0.3s ease;
}

details.faq-item:hover {
  border-color: var(--primary-color);
}

details.faq-item[open] {
  border-color: var(--primary-color);
}

summary {
  padding: 20px;
  cursor: pointer;
  font-weight: 600;
  font-size: 1.1rem;
  list-style: none;
  position: relative;
  padding-right: 40px;
  color: var(--text-color);
}

summary::-webkit-details-marker {
  display: none;
}

summary::after {
  content: "+";
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.5rem;
  color: var(--primary-color);
  transition: transform 0.3s ease;
}

details[open] summary::after {
  transform: translateY(-50%) rotate(45deg);
}

.faq-content {
  padding: 0 20px 20px 20px;
  color: var(--text-muted);
  line-height: 1.7;
  border-top: 1px solid var(--border-color);
}

.faq-content ul {
  padding-left: 20px;
  margin-top: 10px;
}

.faq-content li {
  margin-bottom: 10px;
}

/* Footer Styles */
.site-footer {
  background-color: #0f172a; /* Darker shade */
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 1.5rem;
  margin-top: 4rem;
  font-size: 0.9rem;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-section h4 {
  color: var(--primary-color);
  margin-bottom: 1rem;
  font-size: 1.1rem;
}

.footer-section p {
  color: var(--text-muted);
  line-height: 1.6;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 0.5rem;
}

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

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

.footer-bottom {
  text-align: center;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(45, 212, 191, 0.1);
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* Article Styles */
.article-content {
  max-width: 800px;
  margin: 0 auto;
  background-color: var(--card-bg);
  padding: 40px;
  border-radius: 12px;
  border: 1px solid var(--border-color);
}

.article-content h2 {
  color: var(--primary-color);
  margin-top: 40px;
  margin-bottom: 20px;
  font-size: 1.8rem;
}

.article-content h3 {
  color: var(--text-color);
  margin-top: 30px;
  margin-bottom: 15px;
  font-size: 1.4rem;
}

.article-content p {
  margin-bottom: 20px;
  font-size: 1.1rem;
  line-height: 1.8;
  color: var(--text-muted);
}

.article-content ul {
  margin-bottom: 20px;
  padding-left: 20px;
  color: var(--text-muted);
}

.article-content li {
  margin-bottom: 10px;
}

.article-meta {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 30px;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 20px;
}

.references {
  margin-top: 60px;
  padding-top: 30px;
  border-top: 1px solid var(--border-color);
  font-size: 0.95rem;
}

.references h3 {
  font-size: 1.2rem;
  margin-bottom: 20px;
}

.reference-item {
  margin-bottom: 15px;
  padding-left: 15px;
  border-left: 3px solid var(--secondary-color);
}

/* Simple CSS Chart */
.chart-container {
  margin: 40px 0;
  padding: 30px;
  background: rgba(15, 23, 42, 0.5);
  border-radius: 12px;
  border: 1px solid var(--border-color);
}

.chart-title {
  text-align: center;
  margin-bottom: 30px;
  color: var(--text-color);
  font-weight: bold;
}

.bar-chart {
  display: flex;
  /* align-items: flex-end; Removed to allow groups to stretch */
  justify-content: space-around;
  height: 200px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--text-muted);
}

.bar-group {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-end; /* Push content to bottom */
  height: 100%; /* Take full height of chart */
  width: 20%;
}

.bar {
  width: 100%;
  background: linear-gradient(
    to top,
    var(--secondary-color),
    var(--primary-color)
  );
  border-radius: 4px 4px 0 0;
  transition: height 1s ease-out;
  position: relative;
}

.bar-value {
  position: absolute;
  top: -25px;
  width: 100%;
  text-align: center;
  font-weight: bold;
  color: var(--primary-color);
}

.bar-label {
  margin-top: 10px;
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 768px) {
  .nav-container {
    flex-direction: column;
    height: auto;
    padding: 20px 0;
  }

  nav ul {
    margin-top: 20px;
    flex-wrap: wrap;
    justify-content: center;
  }

  .hero h1 {
    font-size: 2.5rem;
  }
}

/* Back Link Style */
.back-link {
  display: inline-block;
  margin-bottom: 20px;
  color: var(--text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  transition: transform 0.2s ease, color 0.2s ease;
}
.back-link:hover {
  color: var(--primary-color);
  transform: translateX(-5px);
}

/* Utility Classes */
.text-center { text-align: center; }
.mb-20 { margin-bottom: 20px; }
.mb-40 { margin-bottom: 40px; }
.mb-60 { margin-bottom: 60px; }
.text-primary { color: var(--primary-color); }
.text-muted-color { color: var(--text-muted); }
.mx-auto { margin-left: auto; margin-right: auto; }