/* ==========================================================================
   Loci House — blueprint manuscript stylesheet
   One hand: square corners, 1px ruled frames, register marks, no shadows.
   Variable prefix is --atrium- throughout; nothing here is shared with
   any other property in the estate.
   ========================================================================== */

:root {
  --atrium-paper: #f7f4ec;
  --atrium-paper-deep: #efeade;
  --atrium-blueprint: #1f3a5f;
  --atrium-cinnabar: #c56a2e;
  --atrium-slate: #5b6b7c;
  --atrium-rule: #c9c3b4;

  --atrium-rhythm: 26px;
  --atrium-measure: 74ch;
  --atrium-frame: 1px solid var(--atrium-rule);
  --atrium-heavy: 1px solid var(--atrium-blueprint);

  --atrium-display: "Playfair Display", "Songti SC", Georgia, serif;
  --atrium-text: "Work Sans", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --atrium-mono: ui-monospace, "SFMono-Regular", "Cascadia Mono", monospace;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--atrium-paper);
  color: var(--atrium-blueprint);
  font-family: var(--atrium-text);
  font-size: 17px;
  line-height: 1.62;
  font-feature-settings: "kern" 1;
}

a { color: var(--atrium-blueprint); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--atrium-cinnabar); }

.atrium-skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--atrium-blueprint);
  color: var(--atrium-paper);
  padding: 10px 16px;
  z-index: 40;
}
.atrium-skip:focus { left: 8px; top: 8px; }

/* ---------------------------------------------------------------- masthead */

.atrium-masthead {
  border-bottom: var(--atrium-heavy);
  background: var(--atrium-paper);
}

.atrium-mast-inner {
  max-width: 1120px;
  margin: 0 auto;
  padding: 18px 24px 14px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 20px;
}

.atrium-wordmark {
  font-family: var(--atrium-display);
  font-size: 27px;
  letter-spacing: 0.01em;
  margin: 0;
  line-height: 1.1;
}
.atrium-wordmark a { text-decoration: none; }
.atrium-wordmark span {
  display: block;
  font-family: var(--atrium-text);
  font-size: 10px;
  letter-spacing: 0.26em;
  text-transform: uppercase;
  color: var(--atrium-slate);
  margin-top: 6px;
}

.atrium-lang {
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  border: var(--atrium-frame);
  padding: 7px 13px;
  text-decoration: none;
  white-space: nowrap;
}
.atrium-lang:hover { border-color: var(--atrium-cinnabar); }

/* --------------------------------------------------------- return to plan */

.atrium-compass {
  position: fixed;
  right: 22px;
  bottom: 22px;
  width: 62px;
  height: 62px;
  border-radius: 50%;
  border: 1px solid var(--atrium-blueprint);
  background: var(--atrium-paper);
  display: grid;
  place-items: center;
  text-align: center;
  font-size: 9.5px;
  line-height: 1.2;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--atrium-blueprint);
  z-index: 30;
}
.atrium-compass:hover { border-color: var(--atrium-cinnabar); color: var(--atrium-cinnabar); }
.atrium-compass::before {
  content: "";
  position: absolute;
  inset: 5px;
  border: 1px solid var(--atrium-rule);
  border-radius: 50%;
}
.atrium-compass b { font-weight: 600; }

/* ------------------------------------------------------------------ layout */

.atrium-shell {
  max-width: 1120px;
  margin: 0 auto;
  padding: 34px 24px 90px;
}

.atrium-lede {
  max-width: var(--atrium-measure);
  font-size: 18px;
  color: var(--atrium-slate);
  margin: 0 0 26px;
}

.atrium-plate-head {
  border-top: var(--atrium-heavy);
  border-bottom: var(--atrium-frame);
  padding: 14px 0 12px;
  margin-bottom: 22px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 26px;
  align-items: baseline;
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--atrium-slate);
}
.atrium-plate-head strong,
.atrium-plate-head h1 { color: var(--atrium-cinnabar); font-weight: 600; font-size: 11px; margin: 0; letter-spacing: 0.16em; }

/* --------------------------------------------------------------- plan page */

.atrium-house {
  display: block;
  width: 100%;
  height: auto;
  border: var(--atrium-heavy);
  margin-bottom: 8px;
}

.atrium-room .atrium-room-body { transition: fill 120ms linear; }
.atrium-room { cursor: pointer; }
.atrium-room:hover .atrium-room-body,
.atrium-room:focus .atrium-room-body { fill: #f6e2d3; }
.atrium-room .atrium-room-tag {
  opacity: 0.55;
  transition: opacity 120ms linear;
}
.atrium-room:hover .atrium-room-tag,
.atrium-room:focus .atrium-room-tag { opacity: 1; }
.atrium-room.is-shuttered { cursor: default; }
.atrium-room.is-shuttered .atrium-room-body { fill: var(--atrium-paper-deep); }
.atrium-room.is-shuttered .atrium-room-tag { opacity: 0.3; }

.atrium-plan-caption {
  font-size: 12px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--atrium-slate);
  margin: 0 0 34px;
}

/* ------------------------------------------------------------ plain index */

.atrium-index-head {
  font-family: var(--atrium-display);
  font-size: 20px;
  margin: 0 0 4px;
}
.atrium-index-note {
  font-size: 14px;
  color: var(--atrium-slate);
  margin: 0 0 20px;
}

.atrium-roll {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: var(--atrium-frame);
}

.atrium-roll > li {
  border-bottom: var(--atrium-frame);
  padding: 13px 0;
  display: grid;
  grid-template-columns: 62px minmax(0, 1fr) auto;
  gap: 4px 18px;
  align-items: baseline;
}

.atrium-roll .atrium-roll-no {
  font-family: var(--atrium-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--atrium-cinnabar);
}
.atrium-roll .atrium-roll-title { font-size: 17px; }
.atrium-roll .atrium-roll-title a { text-decoration: none; }
.atrium-roll .atrium-roll-note {
  font-size: 13px;
  color: var(--atrium-slate);
  grid-column: 2 / span 2;
  margin: 2px 0 0;
}
.atrium-roll .atrium-roll-meta {
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--atrium-slate);
  white-space: nowrap;
}

/* ------------------------------------------------------------------- tabs */

.atrium-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0;
  border-bottom: var(--atrium-heavy);
  margin: 0 0 26px;
}
.atrium-tab {
  border: var(--atrium-frame);
  border-bottom: none;
  background: transparent;
  font-family: inherit;
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--atrium-slate);
  padding: 9px 15px;
  margin-right: -1px;
  cursor: pointer;
}
.atrium-tab[aria-selected="true"] {
  color: var(--atrium-blueprint);
  background: var(--atrium-paper);
  border-color: var(--atrium-blueprint);
  position: relative;
  top: 1px;
}
.atrium-tab:hover { color: var(--atrium-cinnabar); }

.atrium-family-block { margin-bottom: 40px; }
.atrium-family-block[hidden] { display: none; }
.atrium-family-note {
  font-size: 14px;
  color: var(--atrium-slate);
  margin: 0 0 14px;
}

/* ------------------------------------------------------------- detail page */

.atrium-teach {
  display: grid;
  grid-template-columns: 132px minmax(0, 1fr);
  gap: 0 40px;
  align-items: start;
}

.atrium-rail {
  position: sticky;
  top: 22px;
  border-top: var(--atrium-heavy);
  padding-top: 16px;
}
.atrium-rail ol {
  list-style: none;
  margin: 0;
  padding: 0;
}
.atrium-rail li {
  position: relative;
  padding: 0 0 26px 30px;
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--atrium-slate);
  line-height: 1.35;
}
.atrium-rail li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 4px;
  width: 13px;
  height: 13px;
  border-radius: 50%;
  border: 1px solid var(--atrium-blueprint);
  background: var(--atrium-paper);
  transition: background 140ms linear, border-color 140ms linear;
}
.atrium-rail li:not(:last-child)::after {
  content: "";
  position: absolute;
  left: 6px;
  top: 18px;
  bottom: -2px;
  width: 1px;
  background: var(--atrium-rule);
}
.atrium-rail li.is-lit { color: var(--atrium-blueprint); }
.atrium-rail li.is-lit::before {
  background: var(--atrium-cinnabar);
  border-color: var(--atrium-cinnabar);
}
.atrium-rail a { text-decoration: none; color: inherit; }

.atrium-body { max-width: var(--atrium-measure); }

.atrium-title {
  font-family: var(--atrium-display);
  font-size: 40px;
  line-height: 1.12;
  margin: 0 0 12px;
}
.atrium-hook {
  font-size: 19px;
  color: var(--atrium-cinnabar);
  margin: 0 0 22px;
  max-width: 60ch;
}

.atrium-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 30px;
  border-top: var(--atrium-frame);
  border-bottom: var(--atrium-frame);
  padding: 10px 0;
  margin: 0 0 30px;
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--atrium-slate);
}
.atrium-meta b { color: var(--atrium-blueprint); font-weight: 600; }
.atrium-meta .atrium-byline {
  color: var(--atrium-blueprint);
  font-weight: 600;
  letter-spacing: 0.1em;
}

.atrium-section { margin: 0 0 44px; scroll-margin-top: 26px; }

.atrium-section h2 {
  font-family: var(--atrium-display);
  font-size: 25px;
  margin: 0 0 4px;
  padding-bottom: 8px;
  border-bottom: var(--atrium-frame);
}
.atrium-section h2 em {
  font-style: normal;
  font-family: var(--atrium-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--atrium-cinnabar);
  margin-right: 10px;
}
.atrium-section p { margin: 16px 0 0; }

.atrium-figure {
  display: block;
  width: 100%;
  height: auto;
  border: var(--atrium-heavy);
  margin: 0 0 26px;
  background: var(--atrium-paper);
}

/* steps */

.atrium-moves { list-style: none; margin: 20px 0 0; padding: 0; }
.atrium-moves > li {
  border: var(--atrium-frame);
  border-top: none;
  padding: 16px 18px;
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: 0 16px;
}
.atrium-moves > li:first-child { border-top: var(--atrium-heavy); }
.atrium-moves .atrium-move-no {
  font-family: var(--atrium-display);
  font-size: 26px;
  line-height: 1;
  color: var(--atrium-cinnabar);
}
.atrium-moves h3 {
  font-size: 15px;
  font-weight: 600;
  margin: 0 0 6px;
  letter-spacing: 0.01em;
}
.atrium-moves .atrium-move-example {
  margin: 8px 0 0;
  font-size: 15px;
  color: var(--atrium-slate);
  border-left: 2px solid var(--atrium-rule);
  padding-left: 12px;
}
.atrium-moves .atrium-move-example span {
  display: block;
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--atrium-cinnabar);
  margin-bottom: 2px;
}

/* worked example table */

.atrium-table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0 0;
  font-size: 15.5px;
}
.atrium-table caption {
  text-align: left;
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--atrium-slate);
  padding-bottom: 10px;
}
.atrium-table th,
.atrium-table td {
  border: var(--atrium-frame);
  padding: 11px 13px;
  vertical-align: top;
  text-align: left;
}
.atrium-table thead th {
  background: var(--atrium-paper-deep);
  border-color: var(--atrium-blueprint);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--atrium-blueprint);
  font-weight: 600;
}
.atrium-table tbody tr td:last-child { color: var(--atrium-slate); }

/* pitfalls */

.atrium-faults { list-style: none; margin: 18px 0 0; padding: 0; }
.atrium-faults li {
  border-left: 3px solid var(--atrium-cinnabar);
  padding: 2px 0 2px 16px;
  margin-bottom: 15px;
  font-size: 16px;
}

/* drill + timer */

.atrium-drill {
  border: var(--atrium-heavy);
  padding: 22px 22px 20px;
  margin-top: 18px;
  background: var(--atrium-paper);
}
.atrium-drill .atrium-drill-clock {
  font-family: var(--atrium-mono);
  font-size: 46px;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--atrium-blueprint);
  margin: 0 0 6px;
}
.atrium-drill.is-running .atrium-drill-clock { color: var(--atrium-cinnabar); }
.atrium-drill .atrium-drill-target {
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--atrium-slate);
  margin: 0 0 16px;
}
.atrium-drill-controls { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 16px; }
.atrium-drill button {
  font-family: inherit;
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 9px 16px;
  border: 1px solid var(--atrium-blueprint);
  background: transparent;
  color: var(--atrium-blueprint);
  cursor: pointer;
}
.atrium-drill button:hover { border-color: var(--atrium-cinnabar); color: var(--atrium-cinnabar); }
.atrium-drill button[disabled] { opacity: 0.35; cursor: default; }
.atrium-drill .atrium-drill-hint {
  font-size: 13px;
  color: var(--atrium-slate);
  margin: 0;
}

/* faq */

.atrium-qa { margin: 18px 0 0; }
.atrium-qa details {
  border-bottom: var(--atrium-frame);
  padding: 12px 0;
}
.atrium-qa details:first-of-type { border-top: var(--atrium-frame); }
.atrium-qa summary {
  cursor: pointer;
  font-size: 16px;
  font-weight: 600;
  list-style: none;
}
.atrium-qa summary::-webkit-details-marker { display: none; }
.atrium-qa summary::before {
  content: "?";
  display: inline-block;
  width: 20px;
  color: var(--atrium-cinnabar);
  font-family: var(--atrium-mono);
  font-size: 13px;
}
.atrium-qa details[open] summary { color: var(--atrium-cinnabar); }
.atrium-qa p { margin: 10px 0 0 20px; color: var(--atrium-slate); }

/* disclaimer */

.atrium-scope {
  border: var(--atrium-frame);
  border-left: 3px solid var(--atrium-slate);
  padding: 16px 18px;
  margin: 34px 0 0;
  font-size: 14px;
  color: var(--atrium-slate);
  max-width: var(--atrium-measure);
}
.atrium-scope h2 {
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  margin: 0 0 8px;
  color: var(--atrium-blueprint);
}
.atrium-scope p { margin: 0; }

/* related */

.atrium-next {
  margin: 40px 0 0;
  border-top: var(--atrium-heavy);
  padding-top: 16px;
  max-width: var(--atrium-measure);
}
.atrium-next h2 {
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--atrium-slate);
  margin: 0 0 12px;
}
.atrium-next ul { list-style: none; margin: 0; padding: 0; }
.atrium-next li { padding: 7px 0; border-bottom: var(--atrium-frame); }
.atrium-next li a { text-decoration: none; }

/* --------------------------------------------------------------- legal */

.atrium-doc { max-width: var(--atrium-measure); }
.atrium-doc h2 {
  font-family: var(--atrium-display);
  font-size: 22px;
  margin: 38px 0 0;
  padding-bottom: 7px;
  border-bottom: var(--atrium-frame);
}
.atrium-doc p { margin: 14px 0 0; }
.atrium-doc .atrium-stamp {
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--atrium-cinnabar);
  margin: 0 0 6px;
}

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

.atrium-foot {
  border-top: var(--atrium-heavy);
  margin-top: 20px;
  background: var(--atrium-paper-deep);
}
.atrium-foot-inner {
  max-width: 1120px;
  margin: 0 auto;
  padding: 26px 24px 34px;
  display: flex;
  flex-wrap: wrap;
  gap: 18px 40px;
  justify-content: space-between;
  font-size: 13px;
  color: var(--atrium-slate);
}
.atrium-foot nav { display: flex; flex-wrap: wrap; gap: 6px 20px; }
.atrium-foot nav a { text-decoration: none; color: var(--atrium-slate); }
.atrium-foot nav a:hover { color: var(--atrium-cinnabar); }
.atrium-foot p { margin: 0; max-width: 46ch; }
.atrium-foot p.atrium-foot-scope {
  margin: 8px 0 0;
  max-width: 56ch;
  font-size: 12px;
  opacity: 0.85;
}

/* --------------------------------------------------------------- narrow */

@media (max-width: 860px) {
  .atrium-teach { grid-template-columns: minmax(0, 1fr); }
  .atrium-rail {
    position: static;
    border-bottom: var(--atrium-frame);
    padding-bottom: 12px;
    margin-bottom: 24px;
  }
  .atrium-rail ol { display: flex; flex-wrap: wrap; gap: 0 18px; }
  .atrium-rail li { padding: 0 0 0 20px; }
  .atrium-rail li::after { display: none; }
  .atrium-title { font-size: 30px; }
  .atrium-roll > li { grid-template-columns: 46px minmax(0, 1fr); }
  .atrium-roll .atrium-roll-meta { grid-column: 2; }
  .atrium-compass { right: 14px; bottom: 14px; width: 54px; height: 54px; font-size: 8.5px; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}