/* ============================================================
   DevDocs — Shared Design System
   Unified visual identity for the documentation hub and all
   individual docs. Loaded by every page in / and /docs/**.
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500;600&display=swap');

:root {
  /* base palette */
  --bg:        #080d18;
  --surface:   #0c1220;
  --card:      #101828;
  --border:    #1a2540;
  --border-hi: #253660;
  --text:      #dce6f5;
  --muted:     #6b7fa3;

  /* accent palette */
  --blue:       #4f8ef7;
  --blue-dim:   #1e3a6e;
  --purple:     #8b5cf6;
  --purple-dim: #3b1e6e;
  --green:      #10b981;
  --green-dim:  #0f3d2e;
  --amber:      #f59e0b;
  --amber-dim:  #4a3309;
  --red:        #ef4444;
  --red-dim:    #4a1e1e;
  --cyan:       #22d3ee;

  /* page accent (override per-doc, defaults to blue) */
  --accent:     var(--blue);
  --accent-dim: var(--blue-dim);

  --mono: 'JetBrains Mono', monospace;
  --sans: 'Inter', sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.7;
  font-size: 15px;
  overflow-x: hidden;
}

/* ── BACKDROP: grid + glow blobs ── */
body::before {
  content: '';
  position: fixed; inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 48px 48px;
  opacity: .25;
  pointer-events: none;
  z-index: 0;
}

.glow {
  position: fixed;
  border-radius: 50%;
  filter: blur(140px);
  pointer-events: none;
  z-index: 0;
}
.glow-1 { width: 700px; height: 700px; background: #1e3a6e33; top: -300px; left: -200px; }
.glow-2 { width: 500px; height: 500px; background: #3b1e6e2e; bottom: -200px; right: -100px; }

a { color: inherit; }

/* ============================================================
   SIDEBAR + MAIN — layout for individual doc pages
   ============================================================ */

.sidebar {
  position: fixed;
  top: 0; left: 0;
  width: 240px;
  height: 100vh;
  background: var(--surface);
  border-right: 1px solid var(--border);
  padding: 28px 20px;
  overflow-y: auto;
  z-index: 100;
  display: flex;
  flex-direction: column;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
  text-decoration: none;
  margin-bottom: 24px;
  transition: color .2s;
}
.back-link:hover { color: var(--accent); }

.sidebar-logo {
  display: block;
  text-decoration: none;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .15em;
  text-transform: uppercase;
  color: var(--muted);
  line-height: 1.7;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 6px;
  transition: border-color .15s;
}
.sidebar-logo:hover { border-color: var(--border-hi); }
.sidebar-logo .doc-tag { color: var(--accent); font-weight: 600; }
.sidebar-logo .doc-title {
  display: block;
  font-family: var(--sans);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0;
  text-transform: none;
  color: var(--text);
  margin-top: 6px;
  transition: color .15s;
}
.sidebar-logo:hover .doc-title { color: var(--accent); }

.sidebar nav { display: flex; flex-direction: column; }

.sidebar .nav-section {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: .15em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 18px 0 6px;
}
.sidebar .nav-section:first-of-type { margin-top: 18px; }

.sidebar nav a {
  display: block;
  padding: 6px 10px;
  margin: 0 -10px;
  border-radius: 6px;
  font-size: 13px;
  color: var(--muted);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: color .15s, background .15s, border-color .15s;
}
.sidebar nav a:hover { color: var(--text); background: #ffffff08; }
.sidebar nav a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: var(--accent-dim);
}

.main {
  margin-left: 240px;
  position: relative;
  z-index: 1;
  min-height: 100vh;
}

.wrapper {
  max-width: 860px;
  margin: 0 auto;
  padding: 56px 48px 96px;
}

/* ============================================================
   DOC TYPOGRAPHY
   ============================================================ */

.doc-header { margin-bottom: 64px; }
.doc-num {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--muted);
  letter-spacing: .15em;
  text-transform: uppercase;
  margin-bottom: 16px;
  display: flex; align-items: center; gap: 10px;
}
.doc-num::before {
  content: '';
  width: 32px; height: 1px;
  background: var(--accent);
}

h1 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 700;
  letter-spacing: -.025em;
  line-height: 1.15;
  margin-bottom: 20px;
  color: #fff;
}
h1 em, h1 span.accent { color: var(--accent); font-style: normal; }

.doc-lead {
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 620px;
  line-height: 1.75;
}

.section { margin-bottom: 72px; }
.section-label {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--accent);
  letter-spacing: .18em;
  text-transform: uppercase;
  margin-bottom: 12px;
  display: flex; align-items: center; gap: 10px;
}
.section-label::after {
  content: ''; flex: 1; height: 1px;
  background: linear-gradient(90deg, var(--border-hi), transparent);
}

h2 {
  font-size: 1.4rem;
  font-weight: 600;
  letter-spacing: -.015em;
  margin-bottom: 20px;
  color: var(--text);
}
h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 14px;
  margin-top: 32px;
}
h4 {
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 20px 0 10px;
}

p { color: var(--muted); margin-bottom: 16px; font-size: .95rem; }
p strong, li strong { color: var(--text); font-weight: 500; }
ul, ol { padding-left: 1.3em; color: var(--muted); margin-bottom: 16px; }
li { margin-bottom: 6px; font-size: .95rem; }

/* ============================================================
   COMPARISON / GRID CARDS
   ============================================================ */

.compare, .grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 32px 0;
}
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin: 32px 0;
}
.compare-card, .info-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
}
.compare-card.blue, .info-card.blue   { border-top: 2px solid var(--blue); }
.compare-card.purple, .info-card.purple { border-top: 2px solid var(--purple); }
.compare-card.green, .info-card.green  { border-top: 2px solid var(--green); }
.compare-card.amber, .info-card.amber  { border-top: 2px solid var(--amber); }

.compare-label, .info-label {
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: .15em;
  text-transform: uppercase;
  margin-bottom: 16px;
}
.compare-card.blue .compare-label, .info-card.blue .info-label     { color: var(--blue); }
.compare-card.purple .compare-label, .info-card.purple .info-label { color: var(--purple); }
.compare-card.green .compare-label, .info-card.green .info-label   { color: var(--green); }
.compare-card.amber .compare-label, .info-card.amber .info-label   { color: var(--amber); }

.compare-title, .info-title { font-size: 1.05rem; font-weight: 600; margin-bottom: 16px; color: var(--text); }

.compare-list { list-style: none; display: flex; flex-direction: column; gap: 10px; padding-left: 0; }
.compare-list li {
  font-size: .875rem;
  color: var(--muted);
  padding-left: 18px;
  position: relative;
  line-height: 1.5;
  margin-bottom: 0;
}
.compare-list li::before {
  content: '▸';
  position: absolute; left: 0;
  font-size: 10px;
  top: 3px;
  color: var(--muted);
}
.compare-card.blue .compare-list li::before   { color: var(--blue); }
.compare-card.purple .compare-list li::before { color: var(--purple); }
.compare-card.green .compare-list li::before  { color: var(--green); }
.compare-card.amber .compare-list li::before  { color: var(--amber); }

/* ============================================================
   CALLOUTS
   ============================================================ */

.callout {
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  background: color-mix(in srgb, var(--accent) 8%, transparent);
  border-radius: 0 8px 8px 0;
  padding: 16px 20px;
  margin: 24px 0;
  font-family: var(--mono);
  font-size: .85rem;
  color: var(--text);
  line-height: 1.6;
}
.callout p { color: var(--text); font-family: var(--mono); font-size: .85rem; margin-bottom: 0; }
.callout p + p { margin-top: 8px; }
.callout.blue   { border-left-color: var(--blue);   background: color-mix(in srgb, var(--blue) 8%, transparent); }
.callout.green  { border-left-color: var(--green);  background: color-mix(in srgb, var(--green) 8%, transparent); }
.callout.amber, .callout.warn { border-left-color: var(--amber);  background: color-mix(in srgb, var(--amber) 8%, transparent); }
.callout.purple { border-left-color: var(--purple); background: color-mix(in srgb, var(--purple) 8%, transparent); }
.callout.red, .callout.danger { border-left-color: var(--red); background: color-mix(in srgb, var(--red) 8%, transparent); }

/* ============================================================
   CODE BLOCKS
   ============================================================ */

.code-wrap {
  margin: 24px 0;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid var(--border);
}
.code-header {
  background: var(--surface);
  padding: 10px 18px;
  display: flex; align-items: center; justify-content: space-between;
  border-bottom: 1px solid var(--border);
}
.code-lang {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--muted);
  letter-spacing: .1em;
  text-transform: uppercase;
}
.code-dots { display: flex; gap: 6px; }
.code-dots span { width: 10px; height: 10px; border-radius: 50%; }
.dot-r { background: #ff5f57; }
.dot-y { background: #febc2e; }
.dot-g { background: #28c840; }

pre {
  background: #06090f;
  padding: 24px;
  overflow-x: auto;
  margin: 0;
}
code {
  font-family: var(--mono);
  font-size: .82rem;
  line-height: 1.8;
}
:not(pre) > code {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 6px;
  font-size: .82em;
}

/* Syntax tokens */
.kw  { color: #c792ea; }  /* keyword */
.fn  { color: #82aaff; }  /* function */
.st  { color: #c3e88d; }  /* string */
.cm  { color: #546e7a; font-style: italic; }  /* comment */
.nb  { color: #f78c6c; }  /* number/built-in */
.tp  { color: #ffcb6b; }  /* type */
.op  { color: #89ddff; }  /* operator/punctuation */
.dc  { color: #4f8ef7; }  /* decorator */

/* ============================================================
   DIAGRAM / ASCII BOX
   ============================================================ */

.diagram {
  background: #06090f;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 28px 32px;
  margin: 24px 0;
  overflow-x: auto;
}
.diagram pre {
  background: none;
  padding: 0;
  font-family: var(--mono);
  font-size: .8rem;
  line-height: 1.7;
  color: #8ba3cc;
  white-space: pre;
}
.diagram pre .hi  { color: var(--blue); font-weight: 600; }
.diagram pre .hi2 { color: var(--green); }
.diagram pre .hi3 { color: var(--amber); }
.diagram pre .hi4 { color: var(--purple); }

/* ============================================================
   FLOW STEPS
   ============================================================ */

.flow {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin: 28px 0;
  position: relative;
}
.flow::before {
  content: '';
  position: absolute;
  left: 19px; top: 20px; bottom: 20px;
  width: 1px;
  background: linear-gradient(180deg, var(--accent-dim), transparent);
}
.flow-step {
  display: flex; align-items: flex-start; gap: 16px;
  padding: 16px 0;
  position: relative;
}
.flow-n {
  width: 38px; height: 38px;
  border-radius: 50%;
  background: var(--accent-dim);
  border: 1px solid var(--accent);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 600;
  color: var(--accent);
  flex-shrink: 0;
  z-index: 1;
}
.flow-content { padding-top: 6px; }
.flow-title { font-weight: 600; font-size: .9rem; margin-bottom: 4px; color: var(--text); }
.flow-desc { font-size: .85rem; color: var(--muted); }

/* ============================================================
   PILLS / TAGS / BADGES
   ============================================================ */

.tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 20px; }
.pill {
  font-family: var(--mono);
  font-size: 10px;
  padding: 4px 10px;
  border-radius: 20px;
  border: 1px solid var(--border);
  color: var(--muted);
  background: #ffffff05;
}
.pill.blue   { border-color: var(--blue);   color: var(--blue);   background: #4f8ef712; }
.pill.green  { border-color: var(--green);  color: var(--green);  background: #10b98112; }
.pill.purple { border-color: var(--purple); color: var(--purple); background: #8b5cf612; }
.pill.amber  { border-color: var(--amber);  color: var(--amber);  background: #f59e0b12; }
.pill.red    { border-color: var(--red);    color: var(--red);    background: #ef444412; }

.tag {
  font-family: var(--mono);
  font-size: 10px;
  padding: 3px 8px;
  border-radius: 4px;
  background: #ffffff08;
  border: 1px solid var(--border);
  color: var(--muted);
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--accent-dim);
  border: 1px solid var(--accent);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: .12em;
  text-transform: uppercase;
  padding: 5px 12px;
  border-radius: 4px;
}
.badge.dot::before {
  content: '●';
  font-size: 8px;
  animation: pulse 2s infinite;
}
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: .3; } }

/* ============================================================
   TABLES
   ============================================================ */

.table-wrap {
  overflow-x: auto;
  margin: 24px 0;
  border: 1px solid var(--border);
  border-radius: 10px;
}
table { width: 100%; border-collapse: collapse; font-size: .85rem; }
thead { background: var(--surface); }
th {
  font-family: var(--mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--muted);
  text-align: left;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}
td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  vertical-align: top;
}
tr:last-child td { border-bottom: none; }
tbody tr:hover { background: #ffffff03; }

/* ============================================================
   DOC FOOTER (prev/next nav)
   ============================================================ */

.doc-footer {
  margin-top: 96px;
  padding-top: 32px;
  border-top: 1px solid var(--border);
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: 16px;
}
.doc-footer a {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--accent);
  text-decoration: none;
  display: flex; align-items: center; gap: 8px;
  transition: gap .2s;
}
.doc-footer a:hover { gap: 12px; }
.doc-footer span { font-family: var(--mono); font-size: 11px; color: var(--muted); }

/* ============================================================
   HUB PAGES (index.html / docs/langchain/index.html)
   ============================================================ */

.hub-wrapper {
  position: relative; z-index: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 64px 32px;
}

.hub-header { margin-bottom: 64px; }

.hub-header h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  margin-bottom: 16px;
}
.hub-header h1 span { color: var(--accent); }

.hub-subtitle {
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 620px;
  line-height: 1.7;
}

/* stack visual */
.stack {
  display: flex;
  flex-direction: column;
  margin: 48px 0;
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}
.stack-layer {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 18px 24px;
  border-bottom: 1px solid var(--border);
  transition: background .2s;
}
.stack-layer:last-child { border-bottom: none; }
.stack-layer:hover { background: #ffffff06; }
.layer-icon {
  width: 36px; height: 36px;
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  font-size: 16px;
  flex-shrink: 0;
}
.layer-label {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--muted);
  width: 100px;
  flex-shrink: 0;
}
.layer-desc { font-size: .88rem; color: var(--muted); line-height: 1.5; }
.layer-desc strong { color: var(--text); font-weight: 500; }

/* topic / doc card grid */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-bottom: 56px;
}

.topic-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  gap: 14px;
  transition: border-color .2s, transform .2s, box-shadow .2s;
  position: relative;
  overflow: hidden;
}
.topic-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: var(--accent, var(--blue));
  opacity: 0;
  transition: opacity .2s;
}
.topic-card:hover {
  border-color: var(--border-hi);
  transform: translateY(-2px);
  box-shadow: 0 8px 32px #00000040;
}
.topic-card:hover::before { opacity: 1; }

.topic-card .topic-icon {
  width: 40px; height: 40px;
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  font-size: 18px;
  background: color-mix(in srgb, var(--accent) 12%, transparent);
}

.topic-num {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--muted);
  letter-spacing: .1em;
}
.topic-status {
  font-size: 10px;
  font-family: var(--mono);
  padding: 3px 8px;
  border-radius: 4px;
  font-weight: 600;
  align-self: flex-start;
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  color: var(--accent);
}
.topic-title {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  color: #fff;
}
.topic-desc {
  font-size: .83rem;
  color: var(--muted);
  line-height: 1.6;
  flex: 1;
}
.topic-tags { display: flex; flex-wrap: wrap; gap: 6px; }
.topic-arrow {
  color: var(--muted);
  font-size: .8rem;
  align-self: flex-end;
  transition: color .2s, transform .2s;
}
.topic-card:hover .topic-arrow { color: var(--accent); transform: translateX(4px); }

/* accent colors per card */
.card-blue   { --accent: var(--blue); --accent-dim: var(--blue-dim); }
.card-purple { --accent: var(--purple); --accent-dim: var(--purple-dim); }
.card-green  { --accent: var(--green); --accent-dim: var(--green-dim); }
.card-amber  { --accent: var(--amber); --accent-dim: var(--amber-dim); }
.card-red    { --accent: var(--red); --accent-dim: var(--red-dim); }
.card-cyan   { --accent: var(--cyan); --accent-dim: #103a44; }

/* recently added list */
.recent-list { display: flex; flex-direction: column; gap: 1px; }
.recent-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 14px 16px;
  background: var(--card);
  border-radius: 6px;
  text-decoration: none;
  transition: background .15s;
}
.recent-item:first-child { border-radius: 6px 6px 0 0; }
.recent-item:last-child { border-radius: 0 0 6px 6px; }
.recent-item:only-child { border-radius: 6px; }
.recent-item:hover { background: #ffffff08; }
.recent-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; }
.recent-title { flex: 1; font-size: 14px; color: var(--text); }
.recent-category { font-size: 11px; font-family: var(--mono); color: var(--muted); }
.recent-date { font-size: 11px; color: var(--muted); }

/* hub footer */
.hub-footer {
  border-top: 1px solid var(--border);
  padding-top: 32px;
  margin-top: 32px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  position: relative; z-index: 1;
}
.hub-footer span { font-size: .8rem; color: var(--muted); font-family: var(--mono); }

/* ============================================================
   RESPONSIVE
   ============================================================ */

@media (max-width: 860px) {
  .sidebar { display: none; }
  .main { margin-left: 0; }
  .wrapper { padding: 40px 20px 72px; }
  .compare, .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .hub-wrapper { padding: 48px 20px; }
  .topics-grid { grid-template-columns: 1fr; }
}