:root {
  --ivory: #f7f3ea;
  --ivory-deep: #efe9dc;
  --ink: #14130f;
  --ink-soft: #3b382f;
  --ink-mute: #55503f;
  --rule: #14130f;
  --rule-soft: #c9c1ae;
  --annot: #8c3a06;
  --annot-light: #b4560f;
  --focus: #004b7a;
  --measure: 68ch;
  --serif: Georgia, 'Times New Roman', 'Liberation Serif', serif;
  --sans: 'Helvetica Neue', Helvetica, Arial, 'Liberation Sans', sans-serif;
  --mono: 'Courier New', Courier, 'DejaVu Sans Mono', monospace;
}

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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--ivory);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.6;
  text-rendering: optimizeLegibility;
}

img, svg { max-width: 100%; height: auto; }

h1, h2, h3, h4 {
  font-family: var(--sans);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.06;
  margin: 0 0 0.6em;
  color: var(--ink);
}

h1 { font-size: clamp(2.3rem, 6vw, 4.6rem); }
h2 { font-size: clamp(1.6rem, 3.4vw, 2.5rem); }
h3 { font-size: clamp(1.15rem, 2vw, 1.5rem); }

p { margin: 0 0 1.1em; max-width: var(--measure); }

ul, ol { margin: 0 0 1.2em; padding-left: 1.25em; }
li { margin-bottom: 0.5em; max-width: var(--measure); }

strong { font-weight: 700; }

code, pre, samp {
  font-family: var(--mono);
  font-size: 0.92em;
  background: var(--ivory-deep);
  color: var(--ink);
}

pre {
  overflow-x: auto;
  padding: 1rem;
  border: 1px solid var(--rule-soft);
}

code { padding: 0.08em 0.3em; }
pre code { padding: 0; background: none; }

a {
  color: var(--annot);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

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

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ink);
  color: var(--ivory);
  padding: 0.6rem 1rem;
  z-index: 100;
  font-family: var(--sans);
  font-weight: 700;
}
.skip-link:focus {
  left: 1rem;
  top: 1rem;
}

/* ---- Shared header ---- */
.site-header {
  border-bottom: 1px solid var(--rule);
  background: var(--ivory);
}
.header-inner {
  max-width: 1320px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 1rem 2rem;
  justify-content: space-between;
}
.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 0.6rem;
  font-family: var(--sans);
  font-weight: 800;
  font-size: 1.15rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink);
  text-decoration: none;
}
.brand::before {
  content: "";
  display: inline-block;
  width: 0.7rem;
  height: 1.4rem;
  background: var(--annot-light);
  transform: translateY(0.2rem);
}
nav.site-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
}
nav.site-nav li { margin: 0; }
nav.site-nav a {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 0.82rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  padding-bottom: 0.15rem;
}
nav.site-nav a:hover,
nav.site-nav a:focus-visible {
  color: var(--annot);
  border-bottom-color: var(--annot);
}
nav.site-nav a[aria-current="page"] {
  border-bottom-color: var(--annot);
}

/* ---- Shared footer ---- */
.site-footer {
  border-top: 1px solid var(--rule);
  background: var(--ivory-deep);
  margin-top: 4rem;
}
.footer-inner {
  max-width: 1320px;
  margin: 0 auto;
  padding: 1.75rem 1.5rem 2.5rem;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 2.5rem;
  justify-content: space-between;
  align-items: baseline;
}
.footer-inner p {
  margin: 0;
  font-family: var(--sans);
  font-size: 0.82rem;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
  max-width: 44ch;
}
nav.footer-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.4rem;
}
nav.footer-nav li { margin: 0; }
nav.footer-nav a {
  font-family: var(--sans);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  text-decoration: none;
}
nav.footer-nav a:hover,
nav.footer-nav a:focus-visible { color: var(--annot); text-decoration: underline; }

/* ---- Page shell ---- */
.page {
  display: block;
}
.page.home {
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ---- Home masthead ---- */
.home-masthead {
  padding: 3.25rem 0 2.25rem;
  border-bottom: 1px solid var(--rule);
}
.kicker {
  font-family: var(--sans);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--annot);
  margin: 0 0 1.2rem;
  max-width: none;
}
.home-masthead h1 {
  max-width: 16ch;
  margin-bottom: 1rem;
}
.home-masthead .lede {
  font-size: clamp(1.05rem, 1.6vw, 1.3rem);
  line-height: 1.55;
  color: var(--ink-soft);
  max-width: 62ch;
  margin-bottom: 1.6rem;
}
.masthead-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}
.action-primary,
.action-secondary {
  display: inline-block;
  font-family: var(--sans);
  font-weight: 700;
  font-size: 0.9rem;
  letter-spacing: 0.04em;
  padding: 0.75rem 1.4rem;
  text-decoration: none;
  border: 2px solid var(--ink);
}
.action-primary {
  background: var(--ink);
  color: var(--ivory);
}
.action-primary:hover,
.action-primary:focus-visible {
  background: var(--annot);
  border-color: var(--annot);
  color: var(--ivory);
}
.action-secondary {
  background: transparent;
  color: var(--ink);
}
.action-secondary:hover,
.action-secondary:focus-visible {
  background: var(--ink);
  color: var(--ivory);
}

/* ---- Spreads ---- */
.spread {
  padding: 3rem 0;
  border-bottom: 1px solid var(--rule-soft);
}
.spread-head {
  display: grid;
  grid-template-columns: minmax(3.5rem, auto) 1fr;
  column-gap: 1.5rem;
  align-items: start;
  margin-bottom: 2rem;
}
.spread-number {
  grid-row: 1 / span 2;
  font-family: var(--sans);
  font-weight: 800;
  font-size: clamp(1.6rem, 3.6vw, 2.6rem);
  letter-spacing: -0.03em;
  color: var(--annot-light);
  margin: 0;
  border-top: 3px solid var(--annot-light);
  padding-top: 0.2rem;
  max-width: none;
}
.spread-head h2 {
  margin-bottom: 0.4rem;
  max-width: 26ch;
}
.spread-note {
  grid-column: 2;
  font-family: var(--sans);
  font-size: 0.95rem;
  color: var(--ink-mute);
  max-width: 58ch;
  margin: 0;
}

/* ---- Diagram ---- */
.diagram-figure {
  margin: 0;
  border: 1px solid var(--rule);
  background: var(--ivory);
}
.system-diagram {
  display: block;
  width: 100%;
  height: auto;
}
.diagram-figure figcaption {
  border-top: 1px solid var(--rule-soft);
  padding: 0.9rem 1.1rem;
  font-size: 0.95rem;
  color: var(--ink-soft);
  max-width: none;
}

/* ---- Guides ---- */
.guide-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0;
  border-top: 1px solid var(--rule);
}
.guide-item {
  margin: 0;
  padding: 1.6rem 1.6rem 1.2rem 0;
  border-bottom: 1px solid var(--rule-soft);
  max-width: none;
}
.guide-item:nth-child(odd) { padding-right: 2.2rem; }
.guide-item:nth-child(even) {
  padding-left: 2.2rem;
  border-left: 1px solid var(--rule-soft);
}
.guide-index {
  font-family: var(--sans);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--annot);
  margin: 0 0 0.6rem;
  max-width: none;
}
.guide-item h3 { margin-bottom: 0.5rem; }
.guide-item h3 a { color: var(--ink); text-decoration: none; }
.guide-item h3 a:hover,
.guide-item h3 a:focus-visible { color: var(--annot); text-decoration: underline; }
.guide-item p { color: var(--ink-soft); font-size: 1rem; margin-bottom: 0.4rem; }

/* ---- Exhibits ---- */
.exhibit-list {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--rule);
}
.exhibit {
  display: grid;
  grid-template-columns: minmax(12rem, 18rem) minmax(0, 1fr);
  column-gap: 2rem;
  padding: 1.8rem 0;
  border-bottom: 1px solid var(--rule-soft);
}
.exhibit-tag {
  font-family: var(--sans);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--annot);
  margin: 0;
  padding-top: 0.35rem;
  max-width: none;
}
.exhibit h3 {
  grid-column: 2;
  margin-bottom: 0.6rem;
  font-size: clamp(1.3rem, 2.4vw, 1.8rem);
}
.exhibit h3 a { color: var(--ink); text-decoration: none; border-bottom: 2px solid var(--annot-light); }
.exhibit h3 a:hover,
.exhibit h3 a:focus-visible { color: var(--annot); }
.exhibit-claim,
.exhibit-annot {
  grid-column: 2;
  color: var(--ink-soft);
}
.exhibit-claim { font-size: 1rem; }
.exhibit-annot {
  font-size: 0.95rem;
  color: var(--ink-soft);
  border-left: 3px solid var(--annot-light);
  padding-left: 0.9rem;
  margin-bottom: 0;
}
.annot-label {
  display: block;
  font-family: var(--sans);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--annot);
  margin-bottom: 0.3rem;
}

/* ---- Tool callout ---- */
.tool-callout {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(14rem, 1fr);
  gap: 2rem;
  border: 1px solid var(--rule);
  background: var(--ivory-deep);
  padding: 1.8rem;
}
.tool-callout-body p { color: var(--ink-soft); }
.tool-field-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.35rem 1.5rem;
  border-top: 1px solid var(--rule-soft);
  padding-top: 1rem;
}
.tool-field-list li {
  margin: 0;
  font-family: var(--sans);
  font-size: 0.88rem;
  color: var(--ink);
  border-bottom: 1px dotted var(--rule-soft);
  padding-bottom: 0.3rem;
  max-width: none;
}
.tool-callout-action {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  justify-content: flex-start;
  border-left: 1px solid var(--rule-soft);
  padding-left: 2rem;
}
.tool-callout-fine {
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--ink-mute);
  margin: 0;
  max-width: 30ch;
}

/* ---- Limits ---- */
.limits-list {
  list-style: none;
  margin: 0 0 1.5rem;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.8rem 2rem;
}
.limits-list li {
  margin: 0;
  padding-left: 1.4rem;
  position: relative;
  font-size: 1rem;
  color: var(--ink-soft);
  max-width: none;
}
.limits-list li::before {
  content: "\2014";
  position: absolute;
  left: 0;
  color: var(--annot-light);
  font-weight: 700;
}
.limits-close {
  font-family: var(--sans);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.limits-close a { color: var(--annot); }

/* ---- Article ---- */
article.page.article {
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 1.5rem;
}
.article-header {
  padding: 3rem 0 2rem;
  border-bottom: 1px solid var(--rule);
  max-width: var(--measure);
}
.article-header .kicker { margin-bottom: 1rem; }
.article-header h1 { max-width: 22ch; }
.article-header .lede {
  font-size: clamp(1.05rem, 1.6vw, 1.3rem);
  color: var(--ink-soft);
  max-width: 60ch;
}
.article-body {
  padding: 2.5rem 0 1rem;
  max-width: var(--measure);
}
.article-body h2 { margin-top: 2.2rem; }
.article-body h2:first-child { margin-top: 0; }
.article-body h3 { margin-top: 1.6rem; }
.article-body p,
.article-body li { color: var(--ink-soft); }
.article-body blockquote {
  margin: 1.5rem 0;
  padding: 0.4rem 0 0.4rem 1.2rem;
  border-left: 3px solid var(--annot-light);
  color: var(--ink);
  font-style: italic;
}

/* ---- Source table (article + mobile) ---- */
.source-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.4rem 0 1.8rem;
  font-size: 0.95rem;
}
.source-table caption {
  text-align: left;
  font-family: var(--sans);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--annot);
  padding-bottom: 0.6rem;
}
.source-table th,
.source-table td {
  text-align: left;
  vertical-align: top;
  padding: 0.7rem 0.8rem;
  border-bottom: 1px solid var(--rule-soft);
  color: var(--ink-soft);
}
.source-table th {
  font-family: var(--sans);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink);
  border-bottom: 2px solid var(--rule);
}
.source-table td code { word-break: break-word; }

/* ---- Tool page ---- */
.page--tool {
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 1.5rem;
}
.tool-masthead {
  padding: 3rem 0 2rem;
  border-bottom: 1px solid var(--rule);
}
.tool-masthead h1 { max-width: 24ch; }
.tool-masthead .lede {
  font-size: clamp(1.02rem, 1.5vw, 1.2rem);
  color: var(--ink-soft);
  max-width: 64ch;
}

.noscript-note {
  border: 2px solid var(--annot);
  background: var(--ivory-deep);
  padding: 1.2rem 1.4rem;
  margin: 2rem 0;
}
.noscript-note h2 { font-size: 1.3rem; }
.noscript-note p { margin-bottom: 0; color: var(--ink-soft); }

.tool-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  gap: 2.5rem;
  align-items: start;
  padding: 2.5rem 0;
  border-bottom: 1px solid var(--rule-soft);
}

.tool-form fieldset {
  border: 1px solid var(--rule);
  padding: 1.4rem;
  margin: 0;
  min-width: 0;
}
.tool-form legend {
  font-family: var(--sans);
  font-weight: 800;
  font-size: 1.1rem;
  letter-spacing: -0.01em;
  padding: 0 0.4rem;
}
.fieldset-note {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--ink-mute);
  margin: 0 0 1.2rem;
  max-width: none;
}

.field { margin-bottom: 1.3rem; }
.field label {
  display: block;
  font-family: var(--sans);
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--ink);
  margin-bottom: 0.25rem;
}
.field .hint,
.fieldset-note.hint,
.actions + .hint {
  font-family: var(--sans);
  font-size: 0.82rem;
  line-height: 1.45;
  color: var(--ink-mute);
  margin: 0 0 0.45rem;
  max-width: 60ch;
}
.field textarea,
.field input {
  display: block;
  width: 100%;
  max-width: 100%;
  font-family: var(--serif);
  font-size: 1rem;
  line-height: 1.5;
  color: var(--ink);
  background: #fffdf8;
  border: 1px solid var(--ink-mute);
  padding: 0.55rem 0.65rem;
  resize: vertical;
}
.field textarea:focus-visible,
.field input:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 1px;
  border-color: var(--ink);
}
.field-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 1.2rem;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: 0.6rem;
}
.actions button {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 0.9rem;
  letter-spacing: 0.04em;
  padding: 0.65rem 1.2rem;
  border: 2px solid var(--ink);
  background: var(--ink);
  color: var(--ivory);
  cursor: pointer;
}
.actions button:hover:not(:disabled) {
  background: var(--annot);
  border-color: var(--annot);
  color: var(--ivory);
}
.actions button:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}
.actions button:disabled {
  background: transparent;
  color: #6b6350;
  border-color: #8d8straight;
  border-color: var(--rule-soft);
  cursor: not-allowed;
}
.actions button#reset {
  background: transparent;
  color: var(--ink);
}
.actions button#reset:hover {
  background: var(--ink);
  color: var(--ivory);
}

.tool-error {
  font-family: var(--sans);
  font-size: 0.9rem;
  font-weight: 700;
  color: #7a1f00;
  margin: 1rem 0 0;
  min-height: 1.2em;
  max-width: none;
}
.tool-error:empty { min-height: 0; }

.tool-output { min-width: 0; }
.tool-output h2 { font-size: 1.5rem; }
#results {
  border: 1px solid var(--rule);
  background: #fffdf8;
  padding: 1.2rem 1.3rem;
  min-height: 8rem;
  max-height: 40rem;
  overflow: auto;
}
#results:focus-visible { outline: 3px solid var(--focus); }
#results .placeholder {
  font-family: var(--sans);
  font-size: 0.95rem;
  color: #5b5646;
  margin: 0;
  max-width: 42ch;
}
#results h3 {
  font-size: 1.1rem;
  margin-top: 1.2rem;
}
#results h3:first-child { margin-top: 0; }
#results p, #results li { color: var(--ink-soft); font-size: 0.97rem; }
#results pre { background: var(--ivory-deep); }

.tool-notes {
  padding: 2rem 0 1rem;
  max-width: 72ch;
}
.tool-notes h2 { font-size: 1.4rem; }
.tool-notes p { color: var(--ink-soft); }

/* ---- Reduced motion ---- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ---- Responsive ---- */
@media (max-width: 960px) {
  .guide-list { grid-template-columns: 1fr; }
  .guide-item:nth-child(odd) { padding-right: 0; }
  .guide-item:nth-child(even) {
    padding-left: 0;
    border-left: none;
  }
  .exhibit {
    grid-template-columns: 1fr;
    column-gap: 0;
  }
  .exhibit-tag,
  .exhibit h3,
  .exhibit-claim,
  .exhibit-annot { grid-column: 1; }
  .exhibit-tag { padding-top: 0; margin-bottom: 0.4rem; }
  .tool-callout { grid-template-columns: 1fr; }
  .tool-callout-action {
    border-left: none;
    border-top: 1px solid var(--rule-soft);
    padding-left: 0;
    padding-top: 1.2rem;
  }
  .tool-layout { grid-template-columns: 1fr; gap: 2rem; }
  #results { max-height: none; }
}

@media (max-width: 640px) {
  body { font-size: 17px; }
  .header-inner { padding: 0.9rem 1.1rem; }
  nav.site-nav ul { gap: 0.4rem 1.1rem; }
  .page.home,
  .page--tool,
  article.page.article { padding: 0 1.1rem; }
  .home-masthead { padding: 2.2rem 0 1.6rem; }
  .home-masthead h1 { max-width: none; }
  .spread { padding: 2.2rem 0; }
  .spread-head {
    grid-template-columns: 1fr;
    row-gap: 0.6rem;
  }
  .spread-number {
    grid-row: auto;
    font-size: 1.5rem;
    border-top: none;
    padding-top: 0;
    border-left: 3px solid var(--annot-light);
    padding-left: 0.6rem;
  }
  .spread-note { grid-column: 1; }
  .limits-list { grid-template-columns: 1fr; }
  .tool-field-list { grid-template-columns: 1fr; }
  .tool-callout { padding: 1.2rem; }
  .field-row { grid-template-columns: 1fr; gap: 0; }
  .actions { flex-direction: column; align-items: stretch; }
  .actions button { width: 100%; }
  .article-header { padding: 2.2rem 0 1.6rem; }
  .tool-masthead { padding: 2.2rem 0 1.6rem; }
  .tool-form fieldset { padding: 1rem; }
  .footer-inner {
    padding: 1.4rem 1.1rem 2rem;
    flex-direction: column;
    align-items: flex-start;
  }
  /* Source table becomes stacked blocks on narrow screens */
  .source-table,
  .source-table thead,
  .source-table tbody,
  .source-table th,
  .source-table td,
  .source-table tr { display: block; width: 100%; }
  .source-table thead {
    position: absolute;
    width: 1px; height: 1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
  }
  .source-table tr {
    border: 1px solid var(--rule-soft);
    margin-bottom: 1rem;
    padding: 0.4rem 0.8rem;
  }
  .source-table td {
    border: none;
    padding: 0.35rem 0;
  }
  .source-table td::before {
    content: attr(data-label) ": ";
    font-family: var(--sans);
    font-weight: 700;
    font-size: 0.78rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--ink);
    display: block;
  }
}

@media (max-width: 400px) {
  body { font-size: 16.5px; }
  .header-inner { flex-direction: column; align-items: flex-start; gap: 0.7rem; }
  .brand { font-size: 1rem; }
  .masthead-actions { flex-direction: column; align-items: stretch; }
  .action-primary,
  .action-secondary { text-align: center; }
}

@media print {
  .site-header, .site-footer, .masthead-actions, .actions, .tool-callout-action { display: none; }
  body { background: #fff; color: #000; }
  a { color: #000; }
}