:root {
  color-scheme: dark;
  --bg: #0b0f14;
  --bg-soft: #111821;
  --panel: rgba(18, 27, 37, 0.88);
  --panel-solid: #121b25;
  --ink: #e9edf1;
  --muted: #a9b4bf;
  --faint: #6f7e8d;
  --line: rgba(169, 180, 191, 0.18);
  --accent: #72e0b7;
  --accent-strong: #a2f4d4;
  --amber: #f4bd68;
  --blue: #7dc6ff;
  --red: #ff8f87;
  --terminal: #07100d;
  --terminal-line: #183c30;
  --max: 1180px;
  --reading: 760px;
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background:
    radial-gradient(circle at 12% 8%, rgba(114, 224, 183, 0.08), transparent 28rem),
    radial-gradient(circle at 88% 16%, rgba(125, 198, 255, 0.07), transparent 30rem),
    var(--bg);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.72;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--accent-strong);
  text-decoration-color: rgba(162, 244, 212, 0.45);
  text-underline-offset: 0.18em;
}

a:hover {
  text-decoration-color: currentColor;
}

:focus-visible {
  outline: 3px solid var(--amber);
  outline-offset: 4px;
}

.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 200;
  padding: 0.65rem 0.9rem;
  border-radius: 8px;
  background: var(--ink);
  color: var(--bg);
  font-weight: 700;
  transform: translateY(-180%);
}

.skip-link:focus {
  transform: translateY(0);
}

.progress {
  position: fixed;
  inset: 0 auto auto 0;
  z-index: 100;
  width: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--blue));
  box-shadow: 0 0 18px rgba(114, 224, 183, 0.8);
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--line);
  background: rgba(11, 15, 20, 0.86);
  backdrop-filter: blur(18px);
}

.topbar-inner {
  width: min(calc(100% - 2rem), var(--max));
  min-height: 60px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  color: var(--ink);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-decoration: none;
  text-transform: uppercase;
}

.topnav {
  display: flex;
  align-items: center;
  gap: 1rem;
  color: var(--muted);
  font-size: 0.86rem;
}

.topnav a {
  color: inherit;
  text-decoration: none;
}

.topnav a:hover {
  color: var(--ink);
}

.hero,
.story-hero {
  width: min(calc(100% - 2rem), var(--max));
  margin: 0 auto;
  padding: clamp(4rem, 10vw, 8rem) 0 clamp(3rem, 7vw, 6rem);
}

.story-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(260px, 0.7fr);
  align-items: end;
  gap: clamp(2rem, 6vw, 6rem);
}

.eyebrow,
.chapter-no,
.kicker {
  margin: 0 0 1rem;
  color: var(--accent);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.76rem;
  font-weight: 750;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2,
h3,
h4 {
  color: #f7f9fb;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 600;
  line-height: 1.12;
  text-wrap: balance;
}

h1 {
  max-width: 980px;
  margin: 0;
  font-size: clamp(3rem, 8vw, 7.4rem);
  letter-spacing: -0.052em;
}

.story-hero h1 {
  font-size: clamp(3rem, 6.6vw, 6.2rem);
}

.dek {
  max-width: 760px;
  margin: 1.6rem 0 0;
  color: var(--muted);
  font-size: clamp(1.12rem, 2.2vw, 1.45rem);
  line-height: 1.55;
}

.hero-meta {
  border-left: 1px solid var(--line);
  padding-left: 1.5rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.hero-meta dl {
  margin: 0;
}

.hero-meta div {
  display: grid;
  grid-template-columns: 6.2rem 1fr;
  gap: 0.7rem;
  padding: 0.55rem 0;
  border-bottom: 1px solid var(--line);
}

.hero-meta dt {
  color: var(--faint);
}

.hero-meta dd {
  margin: 0;
  color: var(--ink);
}

.site-main,
.story-shell {
  width: min(calc(100% - 2rem), var(--max));
  margin: 0 auto;
  padding-bottom: 7rem;
}

.story-shell {
  display: grid;
  grid-template-columns: 240px minmax(0, var(--reading));
  justify-content: center;
  gap: clamp(2rem, 6vw, 5rem);
}

.toc {
  align-self: start;
  position: sticky;
  top: 88px;
  max-height: calc(100vh - 112px);
  overflow: auto;
  padding: 1rem 0 1rem 1rem;
  border-left: 1px solid var(--line);
  scrollbar-width: thin;
}

.toc-title {
  margin: 0 0 0.8rem;
  color: var(--faint);
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.toc ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

.toc li + li {
  margin-top: 0.34rem;
}

.toc a {
  display: block;
  padding: 0.2rem 0;
  color: var(--faint);
  font-size: 0.77rem;
  line-height: 1.35;
  text-decoration: none;
  transition: color 140ms ease, transform 140ms ease;
}

.toc a:hover,
.toc a.active {
  color: var(--accent-strong);
  transform: translateX(3px);
}

.story {
  min-width: 0;
}

.chapter {
  padding: 5.2rem 0 1rem;
  scroll-margin-top: 48px;
}

.chapter:first-child {
  padding-top: 1rem;
}

.chapter h2 {
  margin: 0 0 1.6rem;
  font-size: clamp(2.2rem, 5vw, 3.8rem);
  letter-spacing: -0.035em;
}

.chapter h3 {
  margin: 3rem 0 1rem;
  font-size: clamp(1.45rem, 3vw, 2rem);
}

.chapter h4 {
  margin: 2rem 0 0.7rem;
  font-size: 1.2rem;
}

.chapter p,
.chapter li {
  color: #d6dde3;
}

.chapter > p.lead::first-letter {
  float: left;
  margin: 0.07em 0.12em 0 0;
  color: var(--accent-strong);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 4.8rem;
  line-height: 0.76;
}

.chapter ul,
.chapter ol {
  padding-left: 1.35rem;
}

.chapter li + li {
  margin-top: 0.55rem;
}

.lead {
  color: #eef2f5 !important;
  font-size: 1.22rem;
  line-height: 1.65;
}

.lede-rule {
  width: 5rem;
  height: 2px;
  margin: 2rem 0;
  border: 0;
  background: linear-gradient(90deg, var(--accent), transparent);
}

.callout,
.decision,
.lesson,
.privacy-note {
  margin: 2rem 0;
  padding: 1.35rem 1.45rem;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

.callout strong,
.decision strong,
.lesson strong,
.privacy-note strong {
  display: block;
  margin-bottom: 0.45rem;
  color: var(--accent-strong);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.75rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.decision {
  border-color: rgba(244, 189, 104, 0.3);
}

.decision strong {
  color: var(--amber);
}

.privacy-note {
  border-color: rgba(125, 198, 255, 0.3);
}

.privacy-note strong {
  color: var(--blue);
}

blockquote {
  margin: 2.2rem 0;
  padding: 0.4rem 0 0.4rem 1.5rem;
  border-left: 3px solid var(--accent);
  color: #f1f5f7;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.38rem;
  line-height: 1.5;
}

code,
kbd {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

:not(pre) > code {
  padding: 0.1em 0.35em;
  border: 1px solid rgba(114, 224, 183, 0.16);
  border-radius: 5px;
  background: rgba(114, 224, 183, 0.07);
  color: #c8f8e4;
  font-size: 0.86em;
}

.terminal {
  position: relative;
  margin: 2rem 0;
  overflow: hidden;
  border: 1px solid var(--terminal-line);
  border-radius: 14px;
  background: var(--terminal);
  box-shadow: var(--shadow);
}

.terminal::before {
  content: "terminal";
  display: block;
  padding: 0.58rem 0.9rem;
  border-bottom: 1px solid var(--terminal-line);
  color: #709987;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

pre {
  margin: 0;
  overflow-x: auto;
  padding: 1.2rem 1.25rem 1.35rem;
  color: #c6f4de;
  font-size: 0.82rem;
  line-height: 1.62;
  tab-size: 2;
  white-space: pre;
}

.copy-code {
  position: absolute;
  top: 0.42rem;
  right: 0.5rem;
  border: 1px solid var(--terminal-line);
  border-radius: 7px;
  background: rgba(7, 16, 13, 0.92);
  color: #83ae9a;
  cursor: pointer;
  font: 600 0.68rem ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  padding: 0.3rem 0.55rem;
}

.copy-code:hover {
  color: var(--accent-strong);
}

.architecture,
.sequence {
  margin: 2.4rem 0;
  padding: 1.4rem;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: linear-gradient(145deg, rgba(18, 27, 37, 0.9), rgba(11, 15, 20, 0.7));
}

.architecture svg {
  display: block;
  width: 100%;
  height: auto;
}

.diagram-scroll {
  max-width: 100%;
}

.architecture figcaption,
.sequence figcaption {
  margin-top: 1rem;
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.5;
}

.steps {
  display: grid;
  gap: 1rem;
  margin: 2rem 0;
  padding: 0;
  counter-reset: step;
  list-style: none;
}

.steps li {
  position: relative;
  min-height: 3rem;
  padding: 0.95rem 1rem 0.95rem 4rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: rgba(18, 27, 37, 0.58);
}

.steps li::before {
  position: absolute;
  left: 1rem;
  top: 0.9rem;
  width: 2rem;
  height: 2rem;
  border: 1px solid rgba(114, 224, 183, 0.35);
  border-radius: 50%;
  color: var(--accent);
  content: counter(step, decimal-leading-zero);
  counter-increment: step;
  display: grid;
  place-items: center;
  font: 700 0.7rem ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.data-table {
  width: 100%;
  margin: 2rem 0;
  border-collapse: collapse;
  font-size: 0.86rem;
}

.data-table th,
.data-table td {
  padding: 0.78rem 0.7rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.data-table th {
  color: var(--accent-strong);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.data-table td:first-child {
  color: #f0f4f6;
  font-weight: 650;
}

.story-card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  margin: 2rem 0 4rem;
}

.story-card {
  display: flex;
  min-height: 280px;
  flex-direction: column;
  justify-content: space-between;
  padding: 1.5rem;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--panel);
  color: inherit;
  text-decoration: none;
  box-shadow: var(--shadow);
  transition: transform 180ms ease, border-color 180ms ease;
}

.story-card:hover {
  transform: translateY(-4px);
  border-color: rgba(114, 224, 183, 0.45);
}

.story-card h2 {
  margin: 1.1rem 0;
  font-size: 2rem;
}

.story-card p {
  color: var(--muted);
}

.story-card .arrow {
  color: var(--accent);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.8rem;
}

.site-footer {
  width: min(calc(100% - 2rem), var(--max));
  margin: 0 auto;
  padding: 2rem 0 4rem;
  border-top: 1px solid var(--line);
  color: var(--faint);
  font-size: 0.78rem;
}

.site-footer p {
  margin: 0.3rem 0;
}

.end-mark {
  margin: 5rem auto 2rem;
  color: var(--accent);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.8rem;
  letter-spacing: 0.2em;
  text-align: center;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 900px) {
  .story-hero {
    grid-template-columns: 1fr;
  }

  .hero-meta {
    max-width: 620px;
  }

  .story-shell {
    display: block;
  }

  .toc {
    position: relative;
    top: auto;
    max-height: none;
    margin-bottom: 2rem;
    columns: 2;
  }

  .toc-title {
    column-span: all;
  }
}

@media (max-width: 620px) {
  body {
    font-size: 16px;
  }

  .topnav .hide-small {
    display: none;
  }

  .hero,
  .story-hero,
  .site-main,
  .story-shell,
  .site-footer {
    width: min(calc(100% - 1.25rem), var(--max));
  }

  .hero-meta {
    border-left: 0;
    border-top: 1px solid var(--line);
    padding: 1rem 0 0;
  }

  .toc {
    columns: 1;
  }

  .chapter {
    padding-top: 4rem;
  }

  .data-table {
    display: block;
    overflow-x: auto;
  }

  .architecture-wide .diagram-scroll {
    overflow-x: auto;
    padding-bottom: 0.5rem;
    scrollbar-color: var(--accent) var(--bg-soft);
  }

  .architecture-wide .diagram-scroll svg {
    width: 720px;
    max-width: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}

@media print {
  :root {
    color-scheme: light;
  }

  body {
    background: #fff;
    color: #111;
    font-size: 11pt;
  }

  .topbar,
  .progress,
  .toc,
  .copy-code {
    display: none !important;
  }

  .story-hero,
  .story-shell {
    display: block;
    width: 100%;
  }

  .story-hero {
    padding: 1cm 0;
  }

  .chapter {
    padding-top: 1.2cm;
  }

  .chapter p,
  .chapter li,
  .lead,
  .hero-meta,
  .dek {
    color: #222 !important;
  }

  h1,
  h2,
  h3,
  h4 {
    color: #000;
  }

  .callout,
  .decision,
  .lesson,
  .privacy-note,
  .architecture,
  .sequence,
  .terminal {
    break-inside: avoid;
    box-shadow: none;
  }

  .terminal {
    border-color: #777;
    background: #f5f5f5;
  }

  pre {
    color: #111;
    white-space: pre-wrap;
  }
}