/* ============================================================
   CODE TUTORIUM — Blog Stylesheet
   Primary: #1e3a6e (deep navy)  |  Accent: #2f5eb3  |  Background: #ffffff
   Dark mode via [data-theme="dark"]
   ============================================================ */

/* ── RESET & BASE ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --blue-900: #0d1f3c;
  --blue-800: #1e3a6e;
  --blue-700: #254d92;
  --blue-600: #2f5eb3;
  --blue-500: #4472c9;
  --blue-400: #6d96d9;
  --blue-200: #b8cff0;
  --blue-100: #dce8f8;
  --blue-50:  #f0f5fc;

  --bg:        #ffffff;
  --bg-2:      #f8f9fb;
  --bg-3:      #f0f5fc;
  --surface:   #ffffff;
  --border:    #e2e8f0;
  --border-2:  #cbd5e1;

  --text-1:    #1c2333;
  --text-2:    #4a5568;
  --text-3:    #8d97ab;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --shadow-sm: 0 1px 3px rgba(30,58,110,.07), 0 1px 2px rgba(30,58,110,.05);
  --shadow-md: 0 4px 16px rgba(30,58,110,.10);
  --shadow-lg: 0 12px 36px rgba(30,58,110,.14);

  --transition: 160ms ease;
}

/* ── DARK MODE ── */
[data-theme="dark"] {
  --bg:       #0d1220;
  --bg-2:     #121a2e;
  --bg-3:     #172035;
  --surface:  #172035;
  --border:   rgba(255,255,255,.08);
  --border-2: rgba(255,255,255,.14);

  --text-1:   #e8edf5;
  --text-2:   #94a3b8;
  --text-3:   #4f6280;
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: 'Outfit', system-ui, sans-serif;
  font-weight: 400;
  color: var(--text-1);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  transition: background var(--transition), color var(--transition);
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
ul { list-style: none; }
code { font-family: 'DM Mono', monospace; }


/* ── NAVIGATION ── */
.lesson-mega-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--blue-800);
  border-bottom: 1px solid var(--blue-700);
}

.lesson-nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.lesson-nav-left { display: flex; align-items: center; }

.lesson-nav-logo {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 1.2rem;
  color: var(--white, #fff);
  letter-spacing: -.02em;
}

.lesson-nav-logo span { color: var(--blue-400); }

.lesson-nav-right { display: flex; align-items: center; gap: 0.75rem; }

.search-btn,
.hamburger-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: rgba(255,255,255,.08);
  border: 1px solid rgba(255,255,255,.14);
  border-radius: var(--radius-sm);
  color: var(--blue-200);
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}

.search-btn:hover,
.hamburger-btn:hover {
  background: rgba(255,255,255,.16);
  color: #fff;
}

.btn-signin {
  display: inline-flex;
  align-items: center;
  height: 34px;
  padding: 0 1rem;
  background: rgba(255,255,255,.1);
  border: 1px solid rgba(255,255,255,.18);
  border-radius: var(--radius-sm);
  color: #fff;
  font-family: 'Outfit', sans-serif;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  transition: background var(--transition);
}

.btn-signin:hover {
  background: rgba(255,255,255,.18);
}


/* ── BLOG HERO ── */
.blog-hero {
  background: var(--blue-800);
  padding: 5rem 2rem 4rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.blog-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.035) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
}

.blog-hero-badge {
  display: inline-block;
  font-family: 'DM Mono', monospace;
  font-size: 0.8rem;
  color: var(--blue-400);
  background: rgba(109,150,217,.12);
  border: 1px solid rgba(109,150,217,.25);
  padding: 0.375rem 1rem;
  border-radius: 100px;
  margin-bottom: 1.5rem;
  position: relative;
}

.blog-hero h1 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: clamp(2.25rem, 5.5vw, 3.5rem);
  line-height: 1.12;
  color: #fff;
  letter-spacing: -.03em;
  margin-bottom: 1.25rem;
  position: relative;
}

.blog-hero h1 em {
  font-style: italic;
  color: var(--blue-400);
}

.blog-hero-sub {
  font-size: 1.05rem;
  color: var(--blue-200);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.75;
  position: relative;
}


/* ── CATEGORY FILTER ── */
.categories {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
  padding: 2rem 1.5rem;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 60px;
  z-index: 90;
  backdrop-filter: blur(12px);
}

.cat-btn {
  height: 32px;
  padding: 0 1rem;
  background: transparent;
  border: 1px solid var(--border-2);
  border-radius: 100px;
  color: var(--text-2);
  font-family: 'Outfit', sans-serif;
  font-size: 0.825rem;
  font-weight: 500;
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition);
}

.cat-btn:hover {
  background: var(--blue-50);
  border-color: var(--blue-200);
  color: var(--blue-800);
}

.cat-btn.active {
  background: var(--blue-800);
  border-color: var(--blue-800);
  color: #fff;
}

[data-theme="dark"] .cat-btn:hover {
  background: rgba(109,150,217,.12);
  border-color: var(--blue-400);
  color: var(--blue-200);
}

[data-theme="dark"] .cat-btn.active {
  background: var(--blue-600);
  border-color: var(--blue-600);
}


/* ── BLOG GRID ── */
.blog-grid-wrap {
  max-width: 1280px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 5rem;
}

.blog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  gap: 1.125rem;
}


/* ── BLOG CARDS ── */
.blog-card {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.375rem 1.5rem 1.25rem;
  transition:
    box-shadow var(--transition),
    transform var(--transition),
    border-color var(--transition);
  position: relative;
  overflow: hidden;
}

.blog-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--card-color, var(--blue-500));
  opacity: 0;
  transition: opacity var(--transition);
}

.blog-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-3px);
  border-color: var(--border-2);
}

.blog-card:hover::before {
  opacity: 1;
}

.blog-card-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
}

.blog-tag {
  font-family: 'DM Mono', monospace;
  font-size: 0.72rem;
  font-weight: 500;
  padding: 0.2rem 0.625rem;
  border-radius: 100px;
  border: 1px solid;
  background: transparent;
  letter-spacing: .02em;
}

.blog-date {
  font-size: 0.75rem;
  color: var(--text-3);
}

.blog-card-title {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 1rem;
  line-height: 1.4;
  color: var(--text-1);
  flex: 1;
}

.blog-card-excerpt {
  font-size: 0.875rem;
  color: var(--text-2);
  line-height: 1.65;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.blog-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
  margin-top: auto;
}

.blog-read-time {
  font-size: 0.775rem;
  color: var(--text-3);
  font-family: 'DM Mono', monospace;
}

.blog-arrow {
  font-size: 0.85rem;
  font-weight: 600;
  transition: letter-spacing var(--transition);
}

.blog-card:hover .blog-arrow {
  letter-spacing: .04em;
}


/* ── FOOTER ── */
.footer {
  background: var(--blue-900);
  padding: 2.5rem 2rem;
  text-align: center;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 0.125rem;
  justify-content: center;
  margin-bottom: 1.25rem;
}

.footer-links a {
  font-size: 0.875rem;
  color: var(--blue-400);
  padding: 0.375rem 0.875rem;
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
}

.footer-links a:hover {
  color: #fff;
  background: rgba(255,255,255,.07);
}

.footer-copy {
  font-size: 0.8rem;
  color: rgba(255,255,255,.25);
}


/* ── THEME TOGGLE ── */
.theme-toggle-btn {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 200;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--blue-800);
  border: 1px solid var(--blue-600);
  color: #fff;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  transition: background var(--transition), transform var(--transition);
}

.theme-toggle-btn:hover {
  background: var(--blue-700);
  transform: scale(1.08);
}

[data-theme="dark"] .sun-icon { display: none !important; }
[data-theme="dark"] .moon-icon { display: block !important; }
[data-theme="light"] .moon-icon { display: none !important; }
[data-theme="light"] .sun-icon { display: block !important; }


/* ── SEARCH OVERLAY (if needed) ── */
.search-overlay {
  position: fixed;
  inset: 0;
  background: rgba(10,18,35,.65);
  backdrop-filter: blur(4px);
  z-index: 999;
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding-top: 10vh;
}

.search-overlay.open { display: flex; }

.search-box {
  background: var(--surface);
  border: 1px solid var(--border-2);
  border-radius: var(--radius-xl);
  width: min(620px, 92vw);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

.search-header {
  padding: 0.875rem 1.25rem;
  border-bottom: 1px solid var(--border);
}

.search-input-wrap {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.search-icon-svg { color: var(--text-3); flex-shrink: 0; }

.search-input {
  flex: 1;
  border: none;
  outline: none;
  font-family: 'Outfit', sans-serif;
  font-size: 1rem;
  color: var(--text-1);
  background: transparent;
}

.search-input::placeholder { color: var(--text-3); }

.search-esc {
  font-size: 0.75rem;
  font-family: 'DM Mono', monospace;
  color: var(--text-3);
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.2rem 0.5rem;
}

.search-results {
  padding: 1rem 1.25rem;
  min-height: 80px;
}

.search-hint { display: flex; flex-direction: column; gap: 0.5rem; }
.search-hint-row { font-size: 0.875rem; color: var(--text-3); }


/* ── RESPONSIVE ── */
@media (max-width: 768px) {
  .blog-hero { padding: 3.5rem 1.25rem 3rem; }
  .lesson-nav-container { padding: 0 1rem; }
  .blog-grid-wrap { padding: 2rem 1rem 4rem; }
  .blog-grid { grid-template-columns: 1fr; gap: 0.875rem; }
  .categories { top: 60px; padding: 1.25rem 1rem; }
}

@media (max-width: 480px) {
  .lesson-nav-container { height: 54px; }
  .categories { position: static; }
}