:root {
  --navy: #0f172a;
  --navy-light: #1e293b;
  --accent: #3b82f6;
  --accent-dark: #2563eb;
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --border: #334155;
  --white: #ffffff;
  --card-bg: #1e293b;
  --tag-bg: #0f2a4a;
  --tag-text: #60a5fa;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--navy);
  color: var(--text);
  line-height: 1.6;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--white); }

/* ── NAV ── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.nav-brand {
  font-weight: 700;
  font-size: 1rem;
  color: var(--white);
}

.nav-links {
  display: flex;
  gap: 1.75rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s;
}

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

/* ── BUTTONS ── */
.btn {
  display: inline-block;
  padding: 0.55rem 1.2rem;
  border-radius: 6px;
  font-size: 0.875rem;
  font-weight: 600;
  transition: all 0.2s;
  border: none;
  cursor: pointer;
}

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

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }

/* ── INTRO SECTION ── */
.intro-section {
  max-width: 900px;
  margin: 0 auto;
  padding: 5rem 2rem 4rem;
  display: flex;
  align-items: center;
  gap: 4rem;
}

.intro-photo-wrap {
  flex-shrink: 0;
}

.profile-photo {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center top;
  border: 3px solid var(--border);
  display: block;
}

.intro-text {
  flex: 1;
}

.intro-greeting {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 0.25rem;
}

.intro-text h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  color: var(--white);
  letter-spacing: -1px;
  line-height: 1.1;
  margin-bottom: 0.5rem;
}

.intro-tagline {
  font-size: 0.95rem;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: 1.25rem;
}

.intro-bio {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.8;
  margin-bottom: 1rem;
  max-width: 540px;
}

.intro-links {
  display: flex;
  gap: 0.75rem;
  margin-top: 1.5rem;
  flex-wrap: wrap;
}

/* ── COURSES ── */
.courses-section {
  max-width: 900px;
  margin: 0 auto;
  padding: 3rem 2rem 4rem;
  border-top: 1px solid var(--border);
}

.section-heading {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 0.4rem;
}

.section-sub {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

.courses-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

.course-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color 0.2s;
}

.course-card:hover { border-color: var(--accent); }

.course-badge {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--accent);
  background: var(--tag-bg);
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  width: fit-content;
}

.course-card h3 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--white);
  line-height: 1.4;
}

.course-card p {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.7;
  flex: 1;
}

.course-links {
  margin-top: 0.5rem;
}

.course-btn {
  align-self: flex-start;
}

.course-resources {
  margin-top: 1.5rem;
  padding: 1rem 1.25rem;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.resource-label {
  font-weight: 600;
  color: var(--text);
}

.resource-sep {
  color: var(--border);
}

.resource-license {
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* ── CONTACT ── */
.contact-section {
  max-width: 900px;
  margin: 0 auto;
  padding: 3rem 2rem 4rem;
  border-top: 1px solid var(--border);
}

.contact-line {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-top: 0.75rem;
}

.contact-line a { color: var(--accent); }
.contact-line a:hover { color: var(--white); }

/* ── FOOTER ── */
footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 2rem;
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
}

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

/* ── BLOG LISTING PAGE ── */
.blog-listing-hero {
  max-width: 740px;
  margin: 0 auto;
  padding: 4rem 2rem 2rem;
  border-bottom: 1px solid var(--border);
}

.blog-listing-hero h1 {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--white);
  margin-bottom: 0.5rem;
}

.blog-listing-hero p {
  font-size: 0.95rem;
  color: var(--text-muted);
}

.blog-listing {
  max-width: 740px;
  margin: 0 auto;
  padding: 1rem 2rem 4rem;
  display: flex;
  flex-direction: column;
}

.blog-list-card {
  display: block;
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--border);
  color: inherit;
  transition: none;
}

.blog-list-card:hover h2 { color: var(--accent); }
.blog-list-card:hover { text-decoration: none; }

.blog-list-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 0.4rem;
}

.blog-list-card h2 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 0.5rem;
  line-height: 1.4;
  transition: color 0.2s;
}

.blog-list-card p {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 0.75rem;
}

.blog-read-more {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
}

/* ── BLOG POST PAGE ── */
.back-link {
  display: block;
  max-width: 740px;
  margin: 0 auto;
  padding: 1.5rem 2rem 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}
.back-link:hover { color: var(--accent); }

.blog-post-hero {
  max-width: 740px;
  margin: 0 auto;
  padding: 2rem 2rem 2rem;
  border-bottom: 1px solid var(--border);
}

.blog-post-hero h1 {
  font-size: clamp(1.5rem, 3.5vw, 2.2rem);
  font-weight: 800;
  color: var(--white);
  line-height: 1.25;
  margin-bottom: 1rem;
  letter-spacing: -0.5px;
}

.post-meta {
  display: flex;
  gap: 1.5rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.blog-post-content {
  max-width: 740px;
  margin: 0 auto;
  padding: 2.5rem 2rem 4rem;
}

.blog-post-content h2 {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--white);
  margin: 2.5rem 0 0.75rem;
}

.blog-post-content h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--white);
  margin: 1.75rem 0 0.5rem;
}

.blog-post-content p {
  font-size: 0.975rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  line-height: 1.85;
}

.blog-post-content ul,
.blog-post-content ol {
  margin: 0 0 1.25rem 1.5rem;
  color: var(--text-muted);
}

.blog-post-content li {
  font-size: 0.975rem;
  margin-bottom: 0.4rem;
  line-height: 1.7;
}

.blog-post-content pre {
  border-radius: 6px;
  margin-bottom: 1.5rem;
  font-size: 0.85rem;
  line-height: 1.7;
  border: 1px solid var(--border);
}

.blog-post-content pre,
.blog-post-content code {
  font-family: 'Fira Code', 'Cascadia Code', Consolas, monospace;
  font-size: 0.85rem;
}

/* hljs sets its own background — let it; just ensure sizing is right */
.blog-post-content pre code.hljs {
  border-radius: 6px;
  padding: 1.25rem;
}

.blog-post-content code:not(.hljs) {
  background: #020817;
  color: #7dd3fc;
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
  font-size: 0.85em;
}

.blog-post-content img {
  max-width: 100%;
  border-radius: 6px;
  margin: 1rem 0;
  border: 1px solid var(--border);
}

.blog-post-content hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 2rem 0;
}

.blog-post-content blockquote {
  border-left: 3px solid var(--accent);
  padding-left: 1rem;
  margin: 1.5rem 0;
  color: var(--text-muted);
  font-style: italic;
}

/* ── RESPONSIVE ── */
@media (max-width: 680px) {
  nav { padding: 0 1rem; }
  .nav-links { gap: 1rem; }

  .intro-section {
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 3rem 1.25rem 2rem;
    gap: 2rem;
  }

  .intro-bio { max-width: 100%; }
  .intro-links { justify-content: center; }

  .courses-section,
  .contact-section { padding: 2.5rem 1.25rem 3rem; }

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

  .blog-listing-hero,
  .blog-listing { padding-left: 1.25rem; padding-right: 1.25rem; }

  .blog-post-hero,
  .blog-post-content,
  .back-link { padding-left: 1.25rem; padding-right: 1.25rem; }
}