/* ── Custom properties ───────────────────────────────────────────── */
:root {
  --navy:       #204E89;
  --navy-mid:   #0d527f;
  --teal:       #33B449;
  --teal-lt:    #D1F0DE;
  --gold:       #c8922a;
  --cream:      #f8f7f4;
  --cream-dk:   #edeae3;
  --ink:        #1a1a2e;
  --ink-mid:    #3d3d55;
  --ink-lt:     #6b6b82;
  --white:      #ffffff;
  --card-radius:5px;
  --gap:        1.5rem;

  --font-serif: 'DM Serif Display', Georgia, serif;
  --font-sans:  'Inter', 'Hind Siliguri', 'Noto Sans Bengali',
                system-ui, sans-serif;
  --font-mono:  'Times New Roman', 'Courier New', monospace;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--cream);
  color: var(--ink);
  line-height: 1.7;
  font-size: 1rem;
  min-height: 100vh;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }


/* ════════════════════════════════════════
   LISTING PAGE
   ════════════════════════════════════════ */

/* ── Hero ────────────────────────────────────────────────────────── */
.hero {
  background: var(--navy);
  color: var(--white);
  padding: 4.5rem 2rem 3.5rem;
  position: relative;
  overflow: hidden;
}

.hero-grid {
  max-width: 900px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
  text-align: center;
}

.hero-eyebrow {
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: .75rem;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.15;
  margin-bottom: 1rem;
}

.hero-sub {
  font-size: 1.05rem;
  color: rgba(255,255,255,.7);
  max-width: 520px;
  margin: 0 auto;
}

/* DNA decoration */
.hero-dna {
  position: absolute;
  right: -20px;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: 14px;
  opacity: .15;
}
.dna-rung {
  display: block;
  height: 3px;
  background: var(--teal);
  border-radius: 2px;
  width: calc(40px + sin(var(--i, 0) * 0.7) * 30px);
  animation: dna-wave 3s ease-in-out infinite;
  animation-delay: calc(var(--i) * 0.12s);
  /* fallback widths since CSS sin() needs modern browsers */
}
.dna-rung:nth-child(odd)  { width: 60px; }
.dna-rung:nth-child(even) { width: 90px; }
.dna-rung:nth-child(3n)   { width: 75px; }
@keyframes dna-wave {
  0%,100% { opacity:.6; transform: scaleX(1); }
  50%      { opacity:1;  transform: scaleX(1.15); }
}

/* ── Controls strip ──────────────────────────────────────────────── */
.controls-strip {
  background: var(--white);
  border-bottom: 1px solid var(--cream-dk);
  padding: 1.1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 50;
  box-shadow: 0 2px 12px rgba(0,0,0,.06);
}

/* Inner wrapper so search + pills align to the same centred column */
.controls-strip-inner {
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.search-form {
  display: flex;
  align-items: center;
  border: 1.5px solid var(--cream-dk);
  border-radius: 50px;
  padding: .45rem 1.1rem;
  width: 100%;
  max-width: 560px;
  margin-bottom: .85rem;
  background: var(--cream);
  transition: border-color .2s;
}
.search-form:focus-within { border-color: var(--teal); }

.search-icon {
  font-size: 1.2rem;
  color: var(--ink-lt);
  margin-right: .5rem;
  user-select: none;
}

.search-form input {
  flex: 1;
  border: none;
  background: transparent;
  font-family: var(--font-sans);
  font-size: .95rem;
  color: var(--ink);
  outline: none;
}

.topic-filter {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: .45rem;
}

.filter-label {
  font-size: .78rem;
  font-weight: 600;
  color: var(--ink-lt);
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-right: .25rem;
}

.pill {
  font-size: .78rem;
  font-weight: 500;
  padding: .3rem .85rem;
  border-radius: 50px;
  border: 1.5px solid var(--cream-dk);
  color: var(--ink-mid);
  background: var(--cream);
  transition: all .18s;
  white-space: nowrap;
}
.pill:hover       { border-color: var(--teal); color: var(--teal); }
.pill.active      { background: var(--teal); color: var(--white); border-color: var(--teal); }

/* ── Results meta ────────────────────────────────────────────────── */
.results-meta {
  max-width: 1200px;
  margin: 1.5rem auto .5rem;
  padding: 0 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: .875rem;
  color: var(--ink-lt);
}
.results-meta strong { color: var(--ink); }
.clear-link {
  color: var(--teal);
  font-weight: 600;
  font-size: .8rem;
}
.clear-link:hover { text-decoration: underline; }

/* ── Card grid ───────────────────────────────────────────────────── */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--gap);
  max-width: 1200px;
  margin: 0 auto 3rem;
  padding: .5rem 2rem 0;
}

/* ── Card ────────────────────────────────────────────────────────── */
.card {
  background: var(--white);
  border-radius: var(--card-radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--cream-dk);
  transition: box-shadow .22s, transform .22s;
}
.card:hover {
  box-shadow: 0 8px 32px rgba(10,61,98,.12);
  transform: translateY(-3px);
}

.card-banner-link { display: block; }
.card-banner {
  height: 180px;
  background-size: cover;
  background-position: center;
  background-color: var(--navy);
  position: relative;
}

.card-topic-badge {
  position: absolute;
  bottom: .75rem;
  left: .85rem;
  background: var(--teal);
  color: var(--white);
  font-size: .7rem;
  font-weight: 600;
  font-family: var(--font-mono);
  letter-spacing: .06em;
  padding: .2rem .65rem;
  border-radius: 50px;
  text-transform: uppercase;
}

.card-body { padding: 1.2rem 1.35rem .75rem; flex: 1; }

.card-title {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  line-height: 1.35;
  margin-bottom: .55rem;
}
.card-title a { color: var(--navy); }
.card-title a:hover { color: var(--teal); }

.card-excerpt {
  font-size: .875rem;
  color: var(--ink-mid);
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-footer {
  padding: .7rem 1.35rem .9rem;
  border-top: 1px solid var(--cream-dk);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.card-author {
  font-size: .78rem;
  font-weight: 600;
  color: var(--gold);
}

.card-meta {
  display: flex;
  gap: .85rem;
  align-items: center;
  font-size: .75rem;
  color: var(--ink-lt);
}

.card-views {
  display: flex;
  align-items: center;
  gap: .25rem;
}

/* ── Empty state ─────────────────────────────────────────────────── */
.empty-state {
  grid-column: 1 / -1;
  text-align: center;
  padding: 4rem 2rem;
  color: var(--ink-mid);
}
.empty-icon   { font-size: 3.5rem; margin-bottom: 1rem; }
.empty-state h2 { font-family: var(--font-serif); font-size: 1.5rem; margin-bottom: .5rem; }
.btn-primary  {
  display: inline-block;
  margin-top: 1.2rem;
  padding: .6rem 1.5rem;
  background: var(--teal);
  color: var(--white);
  border-radius: 50px;
  font-weight: 600;
}

/* ── Pagination ──────────────────────────────────────────────────── */
.pagination {
  display: flex;
  justify-content: center;
  gap: .5rem;
  padding: 0 2rem 3rem;
}
.pg-btn {
  padding: .45rem .9rem;
  border-radius: 8px;
  border: 1.5px solid var(--cream-dk);
  font-size: .875rem;
  font-weight: 500;
  color: var(--ink-mid);
  background: var(--white);
  transition: all .18s;
}
.pg-btn:hover   { border-color: var(--teal); color: var(--teal); }
.pg-btn.active  { background: var(--navy); color: var(--white); border-color: var(--navy); }


/* ════════════════════════════════════════
   POST PAGE
   ════════════════════════════════════════ */

/* ── Back nav ────────────────────────────────────────────────────── */
.back-nav {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  padding: .85rem 1.5rem;
  font-size: .875rem;
  font-weight: 600;
  color: var(--navy);
  background: var(--white);
  border-bottom: 1px solid var(--cream-dk);
  width: 100%;
  transition: color .18s;
}
.back-nav:hover { color: var(--teal); }

/* ── Post banner ─────────────────────────────────────────────────── */
.post-banner {
  height: clamp(280px, 40vh, 440px);
  background-size: cover;
  background-position: center;
  background-color: var(--navy);
  position: relative;
  display: flex;
  align-items: flex-end;
}

.post-banner-overlay {
  width: 100%;
  padding: 2.5rem 2rem 2rem;
  background: linear-gradient(to top, rgba(10,20,50,.92) 0%, rgba(10,20,50,.4) 60%, transparent 100%);
  color: var(--white);
}

.post-topic-badge {
  display: inline-block;
  background: var(--teal);
  color: var(--white);
  font-size: .7rem;
  font-weight: 700;
  font-family: var(--font-mono);
  letter-spacing: .1em;
  padding: .25rem .8rem;
  border-radius: 50px;
  text-transform: uppercase;
  margin-bottom: .75rem;
}

.post-banner-title {
  font-family: var(--font-serif);
  font-size: clamp(1.5rem, 4vw, 2.5rem);
  line-height: 1.2;
  margin-bottom: 1rem;
  max-width: 820px;
}

.post-meta-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem;
  font-size: .82rem;
  color: rgba(255,255,255,.8);
}
.post-meta-bar span { display: flex; align-items: center; gap: .35rem; }
.post-author { color: #7ecfd4; font-weight: 600; }

/* ── Two-column layout ───────────────────────────────────────────── */
.post-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 2.5rem;
  max-width: 1120px;
  margin: 2.5rem auto;
  padding: 0 2rem;
  align-items: start;
}

/* ── Article content ─────────────────────────────────────────────── */
.post-lede {
  font-size: 1.15rem;
  color: var(--ink-mid);
  font-style: italic;
  border-left: 3px solid var(--teal);
  padding-left: 1.2rem;
  margin-bottom: 2rem;
  line-height: 1.65;
}

.post-body { font-size: 1rem; }

.post-body h2,
.post-body h3,
.post-body h4 {
  font-family: var(--font-serif);
  color: var(--navy);
  margin: 2.2rem 0 .75rem;
  line-height: 1.25;
  scroll-margin-top: 80px;
}
.post-body h2 { font-size: 1.65rem; border-bottom: 2px solid var(--teal-lt); padding-bottom: .4rem; }
.post-body h3 { font-size: 1.25rem; }
.post-body h4 { font-size: 1.05rem; color: var(--ink-mid); }

.post-body p  { margin: 0 0 1.1rem; }

.post-body ul,
.post-body ol {
  margin: 0 0 1.1rem 1.5rem;
}
.post-body li { margin-bottom: .35rem; }

.post-body a   { color: var(--teal); text-decoration: underline; text-decoration-color: var(--teal-lt); }
.post-body a:hover { text-decoration-color: var(--teal); }

/* Tables */
.post-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: .9rem;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 0 0 1px var(--cream-dk);
}
.post-body thead tr   { background: var(--navy); color: var(--white); }
.post-body th         { padding: .65rem 1rem; text-align: left; font-weight: 600; }
.post-body td         { padding: .6rem 1rem; border-bottom: 1px solid var(--cream-dk); }
.post-body tbody tr:nth-child(even) { background: var(--cream); }
.post-body tbody tr:hover           { background: var(--teal-lt); }

/* Code */
.post-body code {
  font-family: var(--font-mono);
  font-size: .875em;
  background: var(--cream-dk);
  padding: .15em .4em;
  border-radius: 4px;
  color: var(--navy-mid);
}
.post-body pre {
  background: #0d1b2a;
  color: #cdd6f4;
  border-radius: 10px;
  padding: 1.25rem 1.5rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  line-height: 1.6;
}
.post-body pre code {
  background: none;
  padding: 0;
  color: inherit;
  font-size: .875rem;
}

/* Mermaid diagrams */
.mermaid {
  background: var(--white);
  border: 1px solid var(--cream-dk);
  border-radius: 10px;
  padding: 1.5rem;
  margin: 1.5rem 0;
  overflow-x: auto;
  text-align: center;
}

/* KaTeX display */
.katex-display {
  margin: 1.5rem 0;
  padding: 1rem 1.5rem;
  background: #f0f8ff;
  border-left: 3px solid var(--navy);
  border-radius: 0 8px 8px 0;
  overflow-x: auto;
}

/* Blockquotes */
.post-body blockquote {
  border-left: 4px solid var(--gold);
  padding: .75rem 1.25rem;
  margin: 1.5rem 0;
  background: var(--cream);
  border-radius: 0 8px 8px 0;
  color: var(--ink-mid);
  font-style: italic;
}

/* Images inside post */
.post-body img {
  border-radius: 8px;
  margin: 1.5rem auto;
  box-shadow: 0 4px 20px rgba(0,0,0,.1);
}

.post-updated {
  margin-top: 2.5rem;
  font-size: .8rem;
  color: var(--ink-lt);
  padding-top: 1rem;
  border-top: 1px solid var(--cream-dk);
}

/* ── Sidebar ─────────────────────────────────────────────────────── */
.post-sidebar {
  position: sticky;
  top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  max-height: calc(100vh - 3rem);
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--cream-dk) transparent;
}

.sidebar-widget {
  background: var(--white);
  border: 1px solid var(--cream-dk);
  border-radius: var(--card-radius);
  padding: 1.1rem;
}

.sidebar-widget-title {
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--ink-lt);
  display: flex;
  align-items: center;
  gap: .4rem;
  margin-bottom: .9rem;
  padding-bottom: .6rem;
  border-bottom: 1px solid var(--cream-dk);
}

/* TOC */
.toc-nav { display: flex; flex-direction: column; gap: .1rem; }

.toc-link {
  display: block;
  font-size: .8rem;
  line-height: 1.45;
  padding: .3rem .6rem;
  border-radius: 5px;
  color: var(--ink-mid);
  border-left: 2px solid transparent;
  transition: all .15s;
}
.toc-link:hover          { color: var(--teal); background: var(--teal-lt); border-left-color: var(--teal); }
.toc-link.active         { color: var(--navy); font-weight: 600; border-left-color: var(--navy); background: var(--teal-lt); }
.toc-level-3             { padding-left: 1.3rem; font-size: .77rem; }
.toc-level-4             { padding-left: 2rem;   font-size: .74rem; color: var(--ink-lt); }

/* Pages list */
.pages-list { list-style: none; display: flex; flex-direction: column; gap: .1rem; }

.pages-list li a {
  display: block;
  font-size: .8rem;
  padding: .35rem .6rem;
  border-radius: 5px;
  color: var(--ink-mid);
  line-height: 1.4;
  transition: all .15s;
}
.pages-list li a:hover       { color: var(--teal); background: var(--teal-lt); }
.pages-list li.current a     { color: var(--navy); font-weight: 600; background: var(--teal-lt); }

.pages-list-date {
  display: block;
  font-size: .7rem;
  color: var(--ink-lt);
  margin-top: .1rem;
}

/* ── Related articles ────────────────────────────────────────────── */
.related-section {
  max-width: 1120px;
  margin: 0 auto 4rem;
  padding: 0 2rem;
  border-top: 1px solid var(--cream-dk);
  padding-top: 2.5rem;
}

.related-title {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  color: var(--navy);
  margin-bottom: 1.5rem;
}
.related-title em { color: var(--teal); font-style: normal; }

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.2rem;
}

.related-card {
  background: var(--white);
  border: 1px solid var(--cream-dk);
  border-radius: var(--card-radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: box-shadow .2s, transform .2s;
}
.related-card:hover {
  box-shadow: 0 6px 24px rgba(10,61,98,.1);
  transform: translateY(-2px);
}

.related-banner {
  height: 130px;
  background-size: cover;
  background-position: center;
  background-color: var(--navy);
}

.related-card-body { padding: .9rem 1rem; }

.related-date { font-size: .73rem; color: var(--ink-lt); display: block; margin-bottom: .3rem; }

.related-card-body h3 {
  font-family: var(--font-serif);
  font-size: .95rem;
  color: var(--navy);
  line-height: 1.35;
}
.related-card:hover h3 { color: var(--teal); }


/* ════════════════════════════════════════
   RESPONSIVE
   ════════════════════════════════════════ */
@media (max-width: 900px) {
  .post-layout {
    grid-template-columns: 1fr;
  }
  .post-sidebar {
    position: static;
    max-height: none;
    order: -1;         /* TOC above article on mobile */
  }
  .pages-widget { display: none; } /* hide full index on mobile */
}

@media (max-width: 640px) {
  .controls-strip { padding: .9rem 1rem; }
  .card-grid { padding: .5rem 1rem 0; gap: 1rem; }
  .hero { padding: 3rem 1rem 2.5rem; }
  .post-banner-overlay { padding: 1.5rem 1rem; }
  .post-layout { padding: 0 1rem; margin-top: 1.5rem; }
  .related-section { padding: 0 1rem; }
}

@media (prefers-reduced-motion: reduce) {
  .dna-rung     { animation: none; }
  .card, .related-card { transition: none; }
}