/*
 * SPDX-FileCopyrightText: 2026 Sandeep Bazar
 * SPDX-License-Identifier: Apache-2.0
 *
 * Palette is lifted from docs/assets/banner.svg so the site, the banner and the
 * architecture SVGs read as one system rather than three.
 */

:root {
  --ink-900: #070b16;
  --ink-850: #0b1020;
  --ink-800: #101736;
  --ink-750: #141a33;
  --ink-700: #1c2547;
  --ink-600: #1e2a52;
  --line: #24305c;

  --text: #eef2ff;
  --text-dim: #aab6d6;
  --text-faint: #7f8db5;

  --cyan: #38bdf8;
  --cyan-soft: #7dd3fc;
  --violet: #6f6cf6;
  --violet-soft: #8ea2ff;
  --green: #34d399;
  --green-soft: #6ee7b7;
  --amber: #fb923c;
  --amber-soft: #fdba74;

  --surface: var(--ink-800);
  --surface-2: var(--ink-750);
  --bg: var(--ink-850);
  --shadow: 0 18px 50px -22px rgb(0 0 0 / 0.85);

  --radius: 14px;
  --radius-sm: 9px;
  --maxw: 1440px;
  --sidebar: 268px;
  --toc: 220px;
  --header-h: 62px;

  --sans: "Inter var", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
    "Helvetica Neue", sans-serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", "Fira Code", Menlo, Consolas, monospace;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --dur: 0.55s;
}

:root[data-theme="light"] {
  --bg: #f7f9fc;
  --surface: #ffffff;
  --surface-2: #eef2f9;
  --line: #dde5f2;
  --text: #0d1428;
  --text-dim: #46577d;
  --text-faint: #6b7a9c;
  --violet: #4f46e5;
  --cyan: #0284c7;
  --shadow: 0 18px 40px -26px rgb(15 23 42 / 0.35);
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 18px);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16.5px;
  line-height: 1.72;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* Ambient field. Fixed so it never scrolls, and purely decorative. */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  background:
    radial-gradient(58rem 30rem at 12% -8%, rgb(111 108 246 / 0.20), transparent 60%),
    radial-gradient(46rem 26rem at 92% 4%, rgb(56 189 248 / 0.14), transparent 62%),
    radial-gradient(40rem 28rem at 50% 108%, rgb(52 211 153 / 0.09), transparent 60%);
  pointer-events: none;
}

:root[data-theme="light"] body::before { opacity: 0.5; }

body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(to right, rgb(148 163 184 / 0.055) 1px, transparent 1px),
    linear-gradient(to bottom, rgb(148 163 184 / 0.055) 1px, transparent 1px);
  background-size: 62px 62px;
  mask-image: radial-gradient(70% 60% at 50% 0%, #000 20%, transparent 100%);
  pointer-events: none;
}

a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

/* ---------------------------------------------------------------- header -- */

.hdr {
  position: sticky;
  top: 0;
  z-index: 60;
  height: var(--header-h);
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 0 22px;
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid var(--line);
}

.hdr__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 680;
  letter-spacing: -0.015em;
  color: var(--text);
  font-size: 15.5px;
}
.hdr__brand:hover { text-decoration: none; }
.hdr__mark { width: 26px; height: 26px; flex: none; }

.hdr__nav { display: flex; gap: 2px; margin-left: 10px; }

.menu { position: relative; }
.menu__t {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 7px 13px;
  border-radius: 999px;
  color: var(--text-dim);
  font-size: 14.2px;
  font-weight: 520;
  transition: color 0.2s, background 0.2s;
}
.menu__t:hover { color: var(--text); background: var(--surface-2); text-decoration: none; }
.menu__t[aria-current="true"] { color: var(--text); background: var(--surface-2); }
.menu__t svg { transition: transform 0.25s var(--ease); opacity: 0.65; }
.menu:hover .menu__t svg, .menu:focus-within .menu__t svg { transform: rotate(180deg); }

.menu__panel {
  position: absolute;
  top: calc(100% + 9px);
  left: -8px;
  width: 320px;
  padding: 16px;
  /* Opaque on purpose: a translucent panel let body text bleed through and
     made the menu unreadable over dense pages. */
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-7px);
  transition: opacity 0.22s var(--ease), transform 0.22s var(--ease), visibility 0.22s;
}
/* Bridges the gap so the panel survives the trip from trigger to panel. */
.menu__panel::before { content: ""; position: absolute; inset: -11px 0 auto 0; height: 11px; }
.menu__panel--wide { width: 560px; }
.menu:hover .menu__panel,
.menu:focus-within .menu__panel { opacity: 1; visibility: visible; transform: none; }

.menu__blurb {
  margin: 0 0 12px 8px;
  font-size: 12.4px;
  color: var(--text-faint);
  letter-spacing: 0.01em;
}
.menu__grid { display: grid; gap: 1px; }
.menu__panel--wide .menu__grid { grid-template-columns: 1fr 1fr; gap: 1px 8px; }
.menu__grid a {
  display: flex;
  gap: 10px;
  padding: 8px 9px;
  border-radius: 9px;
  color: var(--text);
  transition: background 0.16s;
}
.menu__grid a:hover { background: var(--surface-2); text-decoration: none; }
.menu__n {
  flex: none;
  width: 18px;
  font-family: var(--mono);
  font-size: 10.5px;
  line-height: 1.7;
  color: var(--violet-soft);
}
.menu__l { display: block; font-size: 13.6px; font-weight: 560; line-height: 1.35; }
.menu__d {
  display: block;
  font-size: 11.6px;
  line-height: 1.4;
  color: var(--text-faint);
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

.hdr__spacer { flex: 1; }

.iconbtn {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text-dim);
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s, transform 0.2s;
}
.iconbtn:hover { color: var(--text); border-color: var(--violet); transform: translateY(-1px); }
.iconbtn svg { width: 17px; height: 17px; }
.theme-dark-only { display: none; }
:root[data-theme="light"] .theme-dark-only { display: block; }
:root[data-theme="light"] .theme-light-only { display: none; }

.ghlink {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  font-size: 14px;
  font-weight: 560;
  transition: border-color 0.2s, transform 0.2s;
}
.ghlink:hover { border-color: var(--violet); transform: translateY(-1px); text-decoration: none; }
.ghlink svg { width: 16px; height: 16px; }

/* Reading progress */
.progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 100%;
  transform-origin: 0 50%;
  transform: scaleX(var(--p, 0));
  background: linear-gradient(90deg, var(--violet), var(--cyan), var(--green));
  z-index: 70;
}

/* --------------------------------------------------------------- shells --- */

.shell { max-width: var(--maxw); margin: 0 auto; padding: 0 22px; }

.doc {
  display: grid;
  grid-template-columns: var(--sidebar) minmax(0, 1fr) var(--toc);
  gap: 40px;
  align-items: start;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 34px 22px 90px;
}

/* ------------------------------------------------------------- side nav --- */

.side {
  position: sticky;
  top: calc(var(--header-h) + 22px);
  max-height: calc(100vh - var(--header-h) - 44px);
  overflow-y: auto;
  padding-right: 6px;
  scrollbar-width: thin;
}
.side__group + .side__group { margin-top: 26px; }
.side__title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin: 0 0 10px 12px;
}
.side__list { list-style: none; margin: 0; padding: 0; }
.side__list a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 7px 12px;
  border-radius: 9px;
  color: var(--text-dim);
  font-size: 14.2px;
  line-height: 1.45;
  transition: color 0.18s, background 0.18s;
}
.side__list a:hover { color: var(--text); background: var(--surface-2); text-decoration: none; }
.side__list a[aria-current="page"] {
  color: var(--text);
  background: linear-gradient(90deg, color-mix(in srgb, var(--violet) 24%, transparent), transparent);
  box-shadow: inset 2px 0 0 var(--violet);
  font-weight: 580;
}
.side__n {
  flex: none;
  width: 20px;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-faint);
}

/* ------------------------------------------------------------------ toc --- */

.toc {
  position: sticky;
  top: calc(var(--header-h) + 22px);
  max-height: calc(100vh - var(--header-h) - 44px);
  overflow-y: auto;
  font-size: 13.4px;
  scrollbar-width: thin;
}
.toc__title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin: 0 0 10px;
}
.toc ul { list-style: none; margin: 0; padding: 0; border-left: 1px solid var(--line); }
.toc a {
  display: block;
  padding: 5px 0 5px 14px;
  margin-left: -1px;
  border-left: 2px solid transparent;
  color: var(--text-faint);
  transition: color 0.18s, border-color 0.18s;
}
.toc a:hover { color: var(--text); text-decoration: none; }
.toc a.is-active { color: var(--cyan); border-left-color: var(--cyan); }
.toc li.lvl-3 a { padding-left: 26px; font-size: 12.8px; }

/* -------------------------------------------------------------- content --- */

.prose { min-width: 0; max-width: 66rem; }

.prose h1 {
  font-size: clamp(2rem, 1.3rem + 2.2vw, 2.9rem);
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin: 0 0 10px;
  background: linear-gradient(120deg, var(--text) 30%, var(--violet-soft));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.prose h2 {
  font-size: clamp(1.35rem, 1.1rem + 0.8vw, 1.72rem);
  letter-spacing: -0.02em;
  margin: 2.6em 0 0.6em;
  padding-top: 0.5em;
  border-top: 1px solid var(--line);
}
.prose h3 { font-size: 1.16rem; letter-spacing: -0.01em; margin: 2em 0 0.5em; }
.prose h4 { font-size: 1.02rem; margin: 1.6em 0 0.4em; color: var(--text-dim); }

.header-anchor {
  opacity: 0;
  margin-left: 0.4em;
  color: var(--violet);
  font-weight: 400;
  text-decoration: none;
  transition: opacity 0.18s;
}
h2:hover .header-anchor, h3:hover .header-anchor { opacity: 1; }
.header-anchor:focus { opacity: 1; }

.prose p, .prose li { color: var(--text-dim); }
.prose strong { color: var(--text); font-weight: 620; }
.prose ul, .prose ol { padding-left: 1.3em; }
.prose li { margin: 0.35em 0; }
.prose li::marker { color: var(--violet); }

.prose blockquote {
  margin: 1.5em 0;
  padding: 2px 0 2px 20px;
  border-left: 3px solid var(--violet);
  background: linear-gradient(90deg, color-mix(in srgb, var(--violet) 10%, transparent), transparent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.prose blockquote p { color: var(--text-dim); }

.prose code {
  font-family: var(--mono);
  font-size: 0.875em;
  padding: 0.16em 0.42em;
  border-radius: 6px;
  background: var(--surface-2);
  border: 1px solid var(--line);
  color: var(--cyan-soft);
}
:root[data-theme="light"] .prose code { color: #b4269a; }

.prose pre {
  position: relative;
  margin: 1.5em 0;
  padding: 18px 20px;
  overflow-x: auto;
  background: var(--ink-900);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  font-size: 13.6px;
  line-height: 1.62;
}
:root[data-theme="light"] .prose pre { background: #0f172a; }
.prose pre code {
  padding: 0;
  border: 0;
  background: none;
  color: #dbe5ff;
  font-size: inherit;
}

.copy {
  position: absolute;
  top: 10px;
  right: 10px;
  padding: 4px 10px;
  font-size: 11.5px;
  font-family: var(--mono);
  color: var(--text-faint);
  background: rgb(255 255 255 / 0.05);
  border: 1px solid var(--line);
  border-radius: 7px;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.2s, color 0.2s;
}
.prose pre:hover .copy { opacity: 1; }
.copy:hover { color: var(--cyan); }
.copy.ok { color: var(--green); opacity: 1; }

.table-wrap { overflow-x: auto; margin: 1.5em 0; border-radius: var(--radius); border: 1px solid var(--line); }
.prose table { width: 100%; border-collapse: collapse; font-size: 14.4px; }
.prose thead { background: var(--surface-2); }
.prose th, .prose td { padding: 11px 15px; text-align: left; border-bottom: 1px solid var(--line); }
.prose th { color: var(--text); font-weight: 620; white-space: nowrap; }
.prose td { color: var(--text-dim); }
.prose tbody tr { transition: background 0.16s; }
.prose tbody tr:hover { background: color-mix(in srgb, var(--violet) 7%, transparent); }
.prose tbody tr:last-child td { border-bottom: 0; }

.prose img { max-width: 100%; height: auto; border-radius: var(--radius); }
.prose hr { border: 0; border-top: 1px solid var(--line); margin: 2.5em 0; }

/* Mermaid host: sized before render so the reveal does not jump the page. */
.mermaid-wrap {
  margin: 1.8em 0;
  padding: 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow-x: auto;
  min-height: 120px;
  /* Not a centring grid: `place-items: center` sizes the child to max-content,
     which left every diagram at its intrinsic ~300px instead of filling. */
  text-align: center;
}
.mermaid-wrap > .mermaid { width: 100%; }

/* Mermaid's default 1px edges disappear against both themes at this size.
   Thicken every connector and arrowhead, and mark the box as zoomable. */
.mermaid-wrap svg .edgePath .path,
.mermaid-wrap svg .flowchart-link,
.mermaid-wrap svg .messageLine0,
.mermaid-wrap svg .messageLine1,
.mermaid-wrap svg line.actor-line,
.mermaid-wrap svg .relation { stroke-width: 2.2px !important; }
.mermaid-wrap svg .arrowheadPath,
.mermaid-wrap svg marker path { stroke-width: 1.4px !important; }
.mermaid-wrap svg .node rect,
.mermaid-wrap svg .node circle,
.mermaid-wrap svg .node polygon,
.mermaid-wrap svg .cluster rect { stroke-width: 1.8px !important; }
.mermaid-wrap svg .messageText,
.mermaid-wrap svg .nodeLabel,
.mermaid-wrap svg .edgeLabel { font-size: 14px !important; }

.zoomable { cursor: zoom-in; }
.zoomhint {
  position: absolute;
  top: 10px;
  right: 12px;
  display: flex;
  align-items: center;
  gap: 5px;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-faint);
  opacity: 0;
  transition: opacity 0.2s;
  pointer-events: none;
}
.mermaid-wrap { position: relative; }
.mermaid-wrap:hover .zoomhint, .prose figure:hover .zoomhint { opacity: 1; }

/* ------------------------------------------------------------- lightbox -- */

.lightbox {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: grid;
  place-items: center;
  padding: 3.5vh 3vw;
  background: color-mix(in srgb, var(--ink-900) 88%, transparent);
  backdrop-filter: blur(6px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.25s var(--ease), visibility 0.25s;
}
.lightbox[data-open="true"] { opacity: 1; visibility: visible; }
.lightbox__stage {
  width: 100%;
  max-height: 94vh;
  overflow: auto;
  padding: 26px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transform: scale(0.97);
  transition: transform 0.25s var(--ease);
}
.lightbox[data-open="true"] .lightbox__stage { transform: none; }
.lightbox__stage svg { width: 100%; height: auto; max-width: none !important; }
.lightbox__close {
  position: absolute;
  top: 18px;
  right: 22px;
  width: 38px;
  height: 38px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  font-size: 19px;
  line-height: 1;
  cursor: pointer;
}
.lightbox__close:hover { border-color: var(--violet); }
/* Mermaid writes an inline `max-width: NNNpx` on the SVG, which caps diagrams
   at their natural size and leaves them unreadably small in a wide column.
   !important is the only way to beat an inline style from a stylesheet. */
.mermaid-wrap svg { width: 100%; max-width: 100% !important; height: auto; }
.mermaid-wrap[data-state="pending"]::after {
  content: "rendering diagram…";
  font-family: var(--mono);
  font-size: 12.5px;
  color: var(--text-faint);
}
.mermaid-wrap > .mermaid { opacity: 0; transition: opacity 0.6s var(--ease); }
.mermaid-wrap[data-state="done"] > .mermaid { opacity: 1; }

/* ------------------------------------------------------------- prev/next -- */

.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 64px; }
.pager a {
  padding: 16px 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  transition: border-color 0.2s, transform 0.2s;
}
.pager a:hover { border-color: var(--violet); transform: translateY(-2px); text-decoration: none; }
.pager__dir { display: block; font-size: 11.5px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--text-faint); }
.pager__t { color: var(--text); font-weight: 580; }
.pager a.next { text-align: right; grid-column: 2; }

.editlink { margin-top: 40px; font-size: 13.5px; color: var(--text-faint); }

/* ------------------------------------------------------------------ home -- */

.hero { position: relative; padding: 78px 0 34px; text-align: center; }
.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 6px 15px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text-dim);
  font-size: 13px;
  font-family: var(--mono);
}
.hero__dot { width: 7px; height: 7px; border-radius: 50%; background: var(--green); box-shadow: 0 0 0 0 var(--green); animation: pulse 2.4s infinite; }
@keyframes pulse {
  70% { box-shadow: 0 0 0 8px rgb(52 211 153 / 0); }
  100% { box-shadow: 0 0 0 0 rgb(52 211 153 / 0); }
}

.hero h1 {
  margin: 22px auto 0;
  max-width: 17ch;
  font-size: clamp(2.5rem, 1.3rem + 4.4vw, 4.7rem);
  line-height: 1.03;
  letter-spacing: -0.045em;
  font-weight: 720;
  background: linear-gradient(115deg, #fff 12%, var(--violet-soft) 52%, var(--cyan) 92%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
:root[data-theme="light"] .hero h1 {
  background: linear-gradient(115deg, #0d1428 15%, var(--violet) 60%, var(--cyan) 95%);
  -webkit-background-clip: text;
  background-clip: text;
}
.hero__sub {
  margin: 22px auto 0;
  max-width: 62ch;
  font-size: clamp(1rem, 0.94rem + 0.35vw, 1.19rem);
  color: var(--text-dim);
}
.hero__cta { display: flex; flex-wrap: wrap; gap: 13px; justify-content: center; margin-top: 34px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 12px 24px;
  border-radius: 11px;
  font-weight: 580;
  font-size: 15px;
  border: 1px solid transparent;
  transition: transform 0.2s var(--ease), box-shadow 0.2s, border-color 0.2s;
}
.btn:hover { transform: translateY(-2px); text-decoration: none; }
.btn--primary {
  background: linear-gradient(120deg, var(--violet), var(--cyan));
  color: #fff;
  box-shadow: 0 10px 30px -12px var(--violet);
}
.btn--primary:hover { box-shadow: 0 16px 38px -12px var(--violet); }
.btn--ghost { background: var(--surface); border-color: var(--line); color: var(--text); }
.btn--ghost:hover { border-color: var(--violet); }

/* Animated flow diagram */
.flow { margin: 44px auto 0; max-width: 940px; }
.flow svg { width: 100%; height: auto; }
.flow .lane { fill: var(--surface); stroke: var(--line); }
.flow .lbl { fill: var(--text); font-family: var(--sans); font-size: 13px; font-weight: 600; }
.flow .sub { fill: var(--text-faint); font-family: var(--mono); font-size: 10.5px; }
.flow .wire { fill: none; stroke: var(--line); stroke-width: 2; }
.flow .spark {
  fill: none;
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-dasharray: 26 340;
  animation: dash 3.4s linear infinite;
}
@keyframes dash { to { stroke-dashoffset: -366; } }
/* Never dips far enough to read as "disabled" — it is a pulse, not a state. */
.flow .gate { animation: gateGlow 3.4s ease-in-out infinite; }
@keyframes gateGlow {
  0%, 100% { opacity: 0.72; }
  50% { opacity: 1; }
}
.flow .gate rect { transition: filter 0.3s; }
.flow .wire { stroke: color-mix(in srgb, var(--text-faint) 45%, transparent); }

/* Stats */
.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(148px, 1fr));
  gap: 14px;
  margin: 72px 0 0;
  padding: 0;
  list-style: none;
}
.stat {
  padding: 22px 18px;
  text-align: center;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: transform 0.25s var(--ease), border-color 0.25s;
}
.stat:hover { transform: translateY(-3px); border-color: var(--violet); }
.stat__n {
  display: block;
  font-size: clamp(1.7rem, 1.3rem + 1.2vw, 2.3rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
  background: linear-gradient(120deg, var(--cyan), var(--violet-soft));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.stat__l { font-size: 12.6px; color: var(--text-faint); letter-spacing: 0.03em; }

/* `auto` on the sides is load-bearing: `.sec` is also a `.shell`, and a
   `margin: 96px 0 0` shorthand here would reset .shell's `margin: 0 auto`
   and left-align every section on viewports wider than --maxw. */
.sec { margin: 96px auto 0; }
.sec__head { text-align: center; margin-bottom: 34px; }
.sec__head h2 {
  font-size: clamp(1.6rem, 1.2rem + 1.5vw, 2.2rem);
  letter-spacing: -0.03em;
  margin: 0 0 10px;
}
.sec__head p { margin: 0 auto; max-width: 60ch; color: var(--text-dim); }

.layers { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
@media (max-width: 1040px) { .layers { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 560px) { .layers { grid-template-columns: minmax(0, 1fr); } }
.layer {
  position: relative;
  padding: 24px 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform 0.3s var(--ease), border-color 0.3s;
}
.layer::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: linear-gradient(90deg, var(--c1), var(--c2));
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform 0.5s var(--ease);
}
.layer:hover { transform: translateY(-4px); border-color: color-mix(in srgb, var(--c1) 50%, var(--line)); }
.layer.in::before { transform: scaleX(1); }
.layer__n { font-family: var(--mono); font-size: 11.5px; color: var(--c1); letter-spacing: 0.1em; }
.layer h3 { margin: 8px 0 8px; font-size: 1.08rem; letter-spacing: -0.01em; }
.layer p { margin: 0; font-size: 14.3px; color: var(--text-dim); }

/* Explicit column counts, not auto-fit: with six cards, auto-fit produced five
   across and one orphan on a wide screen. Three columns always divides evenly. */
.cards { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
@media (max-width: 1040px) { .cards { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 660px) { .cards { grid-template-columns: minmax(0, 1fr); } }
.card {
  display: block;
  padding: 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: transform 0.28s var(--ease), border-color 0.28s, box-shadow 0.28s;
}
.card:hover {
  transform: translateY(-4px);
  border-color: var(--violet);
  box-shadow: var(--shadow);
  text-decoration: none;
}
.card__k { font-family: var(--mono); font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--text-faint); }
.card h3 { margin: 9px 0 7px; font-size: 1.05rem; color: var(--text); letter-spacing: -0.01em; }
.card p { margin: 0; font-size: 14.2px; color: var(--text-dim); }

/* ---------------------------------------------------------------- footer -- */

.ftr {
  border-top: 1px solid var(--line);
  margin-top: 96px;
  padding: 34px 22px;
  color: var(--text-faint);
  font-size: 13.8px;
}
.ftr__in { max-width: var(--maxw); margin: 0 auto; display: flex; flex-wrap: wrap; gap: 14px; align-items: center; }
.ftr__in nav { display: flex; gap: 18px; margin-left: auto; flex-wrap: wrap; }

/* ------------------------------------------------------------- animation -- */

[data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
  transition-delay: var(--d, 0ms);
}
[data-reveal].in { opacity: 1; transform: none; }

.skip {
  position: absolute;
  left: -9999px;
  top: 8px;
  padding: 10px 16px;
  background: var(--violet);
  color: #fff;
  border-radius: 9px;
  z-index: 100;
}
.skip:focus { left: 12px; }

/* --------------------------------------------------------------- mobile --- */

.side__toggle { display: none; }

@media (max-width: 1180px) {
  .doc { grid-template-columns: var(--sidebar) minmax(0, 1fr); }
  .toc { display: none; }
}

@media (max-width: 900px) {
  .doc { grid-template-columns: minmax(0, 1fr); gap: 0; padding-top: 18px; }
  .side {
    position: static;
    max-height: none;
    overflow: visible;
    margin-bottom: 26px;
    padding: 14px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--surface);
  }
  .side[hidden] { display: none; }
  .side__toggle {
    display: flex;
    align-items: center;
    gap: 9px;
    width: 100%;
    margin-bottom: 14px;
    padding: 11px 15px;
    border: 1px solid var(--line);
    border-radius: var(--radius-sm);
    background: var(--surface);
    color: var(--text);
    font: inherit;
    font-size: 14.5px;
    cursor: pointer;
  }
  .hdr__nav { display: none; }
  .pager { grid-template-columns: 1fr; }
  .pager a.next { grid-column: 1; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  [data-reveal] { opacity: 1; transform: none; }
  .flow .spark { display: none; }
  .hero__dot { animation: none; }
}