/* =========================================================
   Blog EduLulu — 3 Level Architecture Styles
   Brand: Poppins + Nunito, #6C5CE7, #00CEC9
   ========================================================= */

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

:root {
  --primary: #6C5CE7;
  --primary-dark: #5A4BD1;
  --primary-light: #A29BFE;
  --secondary: #00CEC9;
  --accent: #FDCB6E;
  --coral: #E17055;
  --bg: #FFFFFF;
  --bg-alt: #F8F9FA;
  --bg-card: #FFFFFF;
  --text: #2D3436;
  --text-muted: #636E72;
  --text-light: #B2BEC3;
  --border: #E2E8F0;
  --radius: 16px;
  --radius-sm: 8px;
  --radius-lg: 20px;
  --shadow: 0 4px 20px rgba(108,92,231,0.08);
  --shadow-hover: 0 8px 30px rgba(108,92,231,0.15);
  --font-heading: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-body: 'Nunito', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

body {
  font-family: var(--font-body);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  background: var(--bg);
}

.container { max-width: 780px; margin: 0 auto; padding: 0 24px; }

/* ===== HEADER ===== */
.header {
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
  background: white;
  position: sticky; top: 0; z-index: 100;
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}

.logo-text {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--text);
}

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

.logo-badge {
  background: var(--primary);
  color: white;
  padding: 2px 10px;
  border-radius: 100px;
  font-size: 0.6rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-family: var(--font-heading);
}

.nav-links {
  display: flex;
  gap: 16px;
  align-items: center;
}

.nav-link {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 600;
  transition: color 0.2s;
}

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

.nav-link-home {
  background: var(--primary);
  color: white;
  padding: 6px 16px;
  border-radius: 100px;
  font-size: 0.8rem;
}

.nav-link-home:hover {
  background: var(--primary-dark);
  color: white;
}

/* ===== HERO (Level 1) ===== */
.hero {
  padding: 60px 0 40px;
  text-align: center;
  background: linear-gradient(180deg, var(--bg-alt) 0%, white 100%);
}

.hero h1 {
  font-family: var(--font-heading);
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 12px;
}

.hero-subtitle {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 560px;
  margin: 0 auto 24px;
}

.hero-cta { margin-top: 8px; }

.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 12px;
  font-weight: 700;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.2s, box-shadow 0.2s;
  font-family: var(--font-body);
}

.btn-primary {
  background: var(--primary);
  color: white;
  box-shadow: 0 4px 15px rgba(108,92,231,0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(108,92,231,0.4);
}

/* ===== CLUSTER CARDS (Level 1) ===== */
.cluster { padding: 0 0 30px; }

.cluster-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px;
  transition: box-shadow 0.3s, transform 0.2s;
}

.cluster-card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.cluster-card.featured {
  border-color: var(--primary-light);
  background: linear-gradient(135deg, #f8f6ff 0%, white 100%);
}

.cluster-badge {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--primary);
  margin-bottom: 10px;
}

.cluster-title {
  font-family: var(--font-heading);
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 10px;
  line-height: 1.3;
}

.cluster-title a {
  color: var(--text);
  text-decoration: none;
  transition: color 0.2s;
}

.cluster-title a:hover { color: var(--primary); }

.cluster-desc {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 14px;
  line-height: 1.7;
}

.cluster-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 16px;
}

.tag {
  display: inline-block;
  background: var(--bg-alt);
  color: var(--text-muted);
  padding: 3px 10px;
  border-radius: 100px;
  font-size: 0.7rem;
  font-weight: 600;
  font-family: var(--font-heading);
}

.cluster-links { margin-top: 4px; }

.cluster-link {
  display: inline-block;
  color: var(--primary);
  font-weight: 700;
  font-size: 0.95rem;
  text-decoration: none;
  margin-bottom: 12px;
}

.cluster-link:hover { text-decoration: underline; }

.cluster-sublinks {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 16px;
}

.cluster-sublinks a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.85rem;
  position: relative;
  padding-left: 12px;
}

.cluster-sublinks a::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--primary-light);
  font-weight: 700;
}

.cluster-sublinks a:hover { color: var(--primary); }

/* ===== ARTICLE (Level 2+3) ===== */
.article { padding-bottom: 40px; }

.article-header {
  padding: 32px 24px 24px;
  text-align: center;
}

.breadcrumbs {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 12px;
}

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

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

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

.category-badge {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--primary);
  margin-bottom: 12px;
  background: rgba(108,92,231,0.08);
  padding: 3px 12px;
  border-radius: 100px;
}

.article h1 {
  font-family: var(--font-heading);
  font-size: clamp(1.6rem, 3.5vw, 2.2rem);
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 12px;
}

.article-subtitle {
  color: var(--text-muted);
  font-size: 1rem;
  max-width: 600px;
  margin: 0 auto;
}

.article-content {
  padding: 0 24px 30px;
}

.article-content h2 {
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 700;
  margin: 32px 0 12px;
  color: var(--text);
  line-height: 1.3;
}

.article-content h3 {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 600;
  margin: 24px 0 8px;
  color: var(--text);
}

.article-content p {
  margin-bottom: 16px;
  color: var(--text);
  font-size: 0.98rem;
  line-height: 1.8;
}

.article-content ul {
  margin-bottom: 16px;
  padding-left: 24px;
}

.article-content li {
  margin-bottom: 8px;
  color: var(--text);
  font-size: 0.96rem;
  line-height: 1.6;
}

.article-content li strong { color: var(--text); }

.video-container {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  margin-bottom: 24px;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

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

.featured-image {
  width: 100%;
  border-radius: var(--radius);
  margin-bottom: 24px;
  box-shadow: var(--shadow);
}

.back-link {
  display: inline-block;
  color: var(--primary);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  margin-top: 20px;
  padding: 8px 0;
}

.back-link:hover { text-decoration: underline; }

/* ===== RELATED SECTION ===== */
.related-section {
  padding: 0 24px 40px;
}

.related-section h2 {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 20px;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}

.related-card {
  display: block;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  text-decoration: none;
  transition: box-shadow 0.3s, transform 0.2s;
}

.related-card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.related-card h3 {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 8px;
  line-height: 1.3;
}

.related-card p {
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-bottom: 12px;
  line-height: 1.5;
}

.related-link {
  color: var(--primary);
  font-weight: 600;
  font-size: 0.85rem;
}

/* ===== CTA SECTION ===== */
.cta-section {
  padding: 60px 0;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  text-align: center;
  color: white;
}

.cta-section h2 {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.cta-section p {
  color: rgba(255,255,255,0.9);
  margin-bottom: 24px;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
  font-size: 1rem;
}

.cta-button {
  display: inline-block;
  padding: 14px 36px;
  background: white;
  color: var(--primary);
  text-decoration: none;
  border-radius: 12px;
  font-weight: 700;
  font-family: var(--font-body);
  font-size: 1rem;
  transition: transform 0.2s, box-shadow 0.2s;
  box-shadow: 0 4px 15px rgba(0,0,0,0.15);
}

.cta-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0,0,0,0.2);
}

/* ===== FOOTER ===== */
.footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.footer a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 600;
}

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

.footer-small {
  margin-top: 8px;
  font-size: 0.8rem;
  color: var(--text-light);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .hero { padding: 40px 0 30px; }
  .cluster-card { padding: 24px; }
  .cluster-title { font-size: 1.2rem; }
  .related-grid { grid-template-columns: 1fr; }
  .article-header { padding: 24px 16px 16px; }
  .article-content { padding: 0 16px 24px; }
  .related-section { padding: 0 16px 30px; }
}

@media (max-width: 480px) {
  .cluster-sublinks { flex-direction: column; gap: 4px; }
  .cluster-sublinks a { font-size: 0.82rem; }
  .cta-section { padding: 40px 0; }
  .nav-links .nav-link-home { display: none; }
}