/* ============================================================
   STRATUM — a quantitative research letter
   Field: paper #f7f4ec · Ink #20242a · Stroke: teal ink #177d78
   Data series only: depth blue #274b8f · Type: Newsreader + IBM Plex Mono
   ============================================================ */

:root {
  --paper:      #f7f4ec;
  --paper-warm: #f1ecdf;  /* tone tier, warmer back-matter */
  --paper-cool: #eef0ea;  /* tone tier, cooler plate II */
  --paper-deep: #e7e2d3;  /* deepest surface, appendix / rules */
  --ink:        #20242a;
  --ink-70:     #4b4f54;
  --ink-45:     #7c7f81;
  --ink-25:     #adaea9;
  --teal:       #177d78;  /* THE stroke */
  --teal-ink:   #10605c;
  --blue:       #274b8f;  /* data series only */
  --blue-soft:  #6f83b0;
  --rule:       #cec8b7;  /* graph-paper / plate ornament only */

  --serif: "Newsreader", Georgia, serif;
  --mono:  "IBM Plex Mono", ui-monospace, monospace;

  --measure: 34rem;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-optical-sizing: auto;
  font-size: clamp(1.02rem, 0.96rem + 0.3vw, 1.19rem);
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
::selection { background: rgba(23,125,120,0.22); }

a { color: var(--teal-ink); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--ink); }
sub { font-size: 0.7em; }
b { font-weight: 600; }

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

.skip {
  position: absolute; left: -999px; top: 0; z-index: 50;
  background: var(--ink); color: var(--paper); padding: 0.6rem 1rem;
  font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.02em;
}
.skip:focus { left: 0; }

/* ---------- paper grain varnish ---------- */
.grain {
  position: fixed; inset: 0; z-index: 40; pointer-events: none;
  opacity: 0.42; mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)' opacity='0.5'/%3E%3C/svg%3E");
}

/* ---------- core-sample rail (stratigraphic scroll index) ---------- */
.corerail {
  position: fixed; left: clamp(1rem, 2.4vw, 2.2rem); top: 12vh; height: 76vh;
  width: 90px; z-index: 30; display: none; font-family: var(--mono);
}
@media (min-width: 1340px) { .corerail { display: block; } }
.rail-track { position: absolute; left: 6px; top: 0; bottom: 0; width: 1px; background: var(--rule); }
.rail-fill  { position: absolute; left: 6px; top: 0; width: 1px; background: var(--teal);
  height: calc(var(--p, 0) * 100%); }
.rail-dot   { position: absolute; left: 3px; top: calc(var(--p, 0) * 100%);
  width: 7px; height: 7px; background: var(--teal); transform: translateY(-50%); }
.rail-tick  { position: absolute; left: 0; display: flex; align-items: center; gap: 8px;
  transform: translateY(-50%); color: var(--ink-45); font-size: 0.6rem; letter-spacing: 0.14em;
  transition: color 0.3s var(--ease); white-space: nowrap; }
.rail-tick i { display: block; width: 10px; height: 1px; background: var(--ink-25); }
.rail-tick.on { color: var(--teal-ink); }
.rail-tick.on i { background: var(--teal); width: 13px; }

/* ============================================================
   MASTHEAD
   ============================================================ */
.masthead {
  position: relative;
  min-height: 100svh;
  padding: clamp(1.6rem, 4vw, 3.4rem);
  display: flex; flex-direction: column; justify-content: center;
  overflow: hidden;
}
.plate-rings {
  position: absolute; top: 50%; left: 68%;
  width: min(120vh, 74vw); aspect-ratio: 1; transform: translate(-50%, -50%);
  color: var(--teal); opacity: 0.18; z-index: 0;
}
.plate-rings circle, .plate-rings line { vector-effect: non-scaling-stroke; }
.plate-cross { opacity: 0.6; }
.plate-ticks { opacity: 0.8; }

.mast-grid {
  position: relative; z-index: 2;
  width: min(1180px, 100%); margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(15rem, 20rem);
  grid-template-areas:
    "word   word"
    "kicker kicker"
    "body   meta"
    "cue    cue";
  column-gap: clamp(2rem, 5vw, 5rem); row-gap: clamp(1.4rem, 3vw, 2.6rem);
  align-items: end;
}
.wordmark {
  grid-area: word; margin: 0;
  font-family: var(--serif); font-weight: 500;
  font-size: clamp(3.4rem, 12vw, 9.5rem); line-height: 0.9;
  letter-spacing: 0.16em; text-indent: 0.16em;
  color: var(--ink);
}
.kicker {
  grid-area: kicker; margin: 0;
  font-family: var(--mono); font-size: clamp(0.66rem, 1.4vw, 0.82rem);
  letter-spacing: 0.18em; text-transform: uppercase; color: var(--teal-ink);
  display: flex; flex-wrap: wrap; gap: 0.6em; align-items: center;
  padding-top: 0.4rem;
}
.kicker .dot { color: var(--ink-25); }

.mast-body { grid-area: body; position: relative; align-self: end; }
.ghost-num {
  position: absolute; right: -0.5rem; bottom: 1.2rem; z-index: -1;
  font-family: var(--serif); font-weight: 500; font-size: clamp(9rem, 24vw, 20rem);
  line-height: 0.8; color: var(--ink); opacity: 0.045;
  pointer-events: none; user-select: none;
}
h1 {
  margin: 0 0 1.1rem;
  font-family: var(--serif); font-weight: 500;
  font-size: clamp(2.5rem, 6.2vw, 5rem); line-height: 1.02;
  letter-spacing: -0.015em; text-wrap: balance;
}
.deck {
  margin: 0 0 1.3rem; max-width: 32rem;
  font-size: clamp(1.12rem, 1rem + 0.5vw, 1.42rem); line-height: 1.48;
  color: var(--ink-70); text-wrap: pretty;
}
.byline {
  margin: 0; font-family: var(--mono); font-size: 0.76rem;
  letter-spacing: 0.02em; color: var(--ink-45); max-width: 30rem;
}

.mast-meta {
  grid-area: meta; margin: 0; align-self: end;
  border-top: 2px solid var(--ink);
  padding-top: 0.9rem;
}
.mast-meta > div {
  display: grid; grid-template-columns: 1fr; gap: 0.05rem;
  padding: 0.5rem 0;
  background-image: linear-gradient(to right, var(--rule) 40%, transparent 0);
  background-position: top; background-size: 8px 1px; background-repeat: repeat-x;
}
.mast-meta > div:first-child { background: none; }
.mast-meta dt {
  font-family: var(--mono); font-size: 0.64rem; text-transform: uppercase;
  letter-spacing: 0.16em; color: var(--teal-ink);
}
.mast-meta dd { margin: 0; font-family: var(--mono); font-size: 0.86rem; color: var(--ink); }

.scroll-cue {
  grid-area: cue; margin: clamp(1.6rem, 4vw, 3rem) 0 0;
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.18em;
  text-transform: uppercase; color: var(--ink-45);
  display: flex; align-items: center; gap: 0.7em;
}
.scroll-cue span { display: inline-block; animation: bob 2.4s var(--ease) infinite; }
@keyframes bob { 0%,100%{ transform: translateY(0); } 50%{ transform: translateY(4px); } }

/* ============================================================
   PLATES — shared editorial grid
   ============================================================ */
.plate, .appendix {
  position: relative;
  padding-block: clamp(3.4rem, 8vw, 7rem);
  padding-inline: max(clamp(1.6rem, 4vw, 3.4rem), calc((100% - 1180px) / 2));
}
.plate {
  display: grid;
  grid-template-columns: minmax(14rem, 19rem) minmax(0, 1fr);
  column-gap: clamp(2rem, 5vw, 5rem);
}
.plate--ii { background: var(--paper-cool); }

.col-side { position: relative; }
.col-main { max-width: 46rem; }

.plate-tag {
  margin: 0 0 0.2rem; font-family: var(--mono); font-weight: 600;
  font-size: 0.74rem; letter-spacing: 0.22em; text-transform: uppercase;
  color: var(--teal-ink);
}
.fig-no {
  margin: 0 0 1.6rem; font-family: var(--mono); font-size: 0.7rem;
  letter-spacing: 0.08em; color: var(--ink-45);
}
.plate-h {
  margin: 0 0 1.1rem; font-family: var(--serif); font-weight: 500;
  font-size: clamp(2rem, 4.4vw, 3.3rem); line-height: 1.04;
  letter-spacing: -0.012em; text-wrap: balance;
}
.plate-h::after {
  content: ""; display: block; width: 3.2rem; height: 3px;
  background: var(--teal); margin-top: 0.85rem;
}
.lede {
  margin: 0 0 1.1rem; font-size: clamp(1.14rem, 1rem + 0.55vw, 1.5rem);
  line-height: 1.42; color: var(--ink); text-wrap: pretty;
}
.body { margin: 0 0 1.8rem; max-width: var(--measure); color: var(--ink-70); text-wrap: pretty; }
.body b { color: var(--ink); font-variant-numeric: tabular-nums; }

/* marginalia */
.margin {
  font-family: var(--mono); font-size: 0.79rem; line-height: 1.62;
  color: var(--ink-70); max-width: 20rem;
}
.margin p { margin: 0 0 1.1rem; }
.marg-lead { color: var(--teal-ink); font-weight: 600; }

/* ---------- figures / charts ---------- */
.figure { margin: 0 0 0.5rem; }
.chart-wrap {
  position: relative; width: 100%; aspect-ratio: 16 / 8;
  background:
    linear-gradient(var(--paper) 0 0) padding-box;
  background-color: color-mix(in srgb, var(--paper) 88%, #fff);
}
.plate--ii .chart-wrap { background-color: color-mix(in srgb, var(--paper-cool) 84%, #fff); }
.chart-wrap canvas { display: block; width: 100%; height: 100%; }
.cmark { position: absolute; width: 9px; height: 9px; border: 0 solid var(--teal);
  opacity: 0.5; pointer-events: none; }
.cmark.tl { top: 6px; left: 6px; border-top-width: 1.5px; border-left-width: 1.5px; }
.cmark.tr { top: 6px; right: 6px; border-top-width: 1.5px; border-right-width: 1.5px; }
.cmark.bl { bottom: 6px; left: 6px; border-bottom-width: 1.5px; border-left-width: 1.5px; }
.cmark.br { bottom: 6px; right: 6px; border-bottom-width: 1.5px; border-right-width: 1.5px; }
figcaption {
  margin-top: 0.9rem; font-family: var(--mono); font-size: 0.74rem;
  line-height: 1.55; color: var(--ink-45); max-width: 40rem;
}
.cap-no { color: var(--teal-ink); font-weight: 600; }

/* ---------- data table (lab record) ---------- */
.record {
  width: 100%; margin: 2rem 0 0; border-collapse: collapse;
  font-family: var(--mono); font-size: 0.82rem;
  font-variant-numeric: tabular-nums;
}
.record caption {
  text-align: left; font-size: 0.72rem; color: var(--ink-45);
  margin-bottom: 0.7rem;
}
.record thead th {
  text-align: right; font-weight: 600; color: var(--teal-ink);
  font-size: 0.68rem; letter-spacing: 0.1em; text-transform: uppercase;
  padding: 0 0 0.5rem; border-bottom: 2px solid var(--ink);
}
.record thead th:first-child { text-align: left; }
.record td {
  text-align: right; padding: 0.44rem 0; color: var(--ink);
  background-image: linear-gradient(to right, var(--rule) 45%, transparent 0);
  background-position: bottom; background-size: 6px 1px; background-repeat: repeat-x;
}
.record td:first-child { text-align: left; color: var(--teal-ink); }
.record tr[data-open="1"] td { color: var(--ink-45); font-style: italic; }
.record tr[data-open="1"] td:first-child { color: var(--ink-45); }
.record .rec-foot td { background: none; padding-top: 0.7rem; text-align: left;
  font-size: 0.7rem; font-style: italic; color: var(--ink-45); }

/* ============================================================
   PLATE IV — felt report
   ============================================================ */
.plate--felt {
  display: block; max-width: none; background: var(--paper-warm);
  padding-block: clamp(4rem, 9vw, 8rem);
}
.felt-inner { width: min(46rem, 100%); margin: 0 auto; }
.felt-h { font-style: italic; }
.felt-h::after { display: none; }
.felt-body { margin-top: 1.4rem; }
.felt-body p {
  margin: 0 0 1.3rem; font-size: clamp(1.14rem, 1rem + 0.5vw, 1.42rem);
  line-height: 1.56; color: var(--ink-70); text-wrap: pretty;
}
.felt-body p:first-child::first-letter {
  font-size: 3.4em; line-height: 0.78; float: left;
  padding: 0.05em 0.12em 0 0; color: var(--teal); font-weight: 500;
}
.felt-sign {
  font-style: italic; color: var(--ink) !important;
  border-top: 2px solid var(--ink); padding-top: 1.2rem; margin-top: 1.8rem !important;
  max-width: 32rem;
}

/* ============================================================
   APPENDIX
   ============================================================ */
.appendix {
  display: grid;
  grid-template-columns: minmax(14rem, 19rem) minmax(0, 1fr);
  column-gap: clamp(2rem, 5vw, 5rem);
  background: var(--paper-deep);
}
.appendix-main { max-width: 52rem; }
.ap-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: clamp(1.6rem, 4vw, 3rem); margin-top: 1rem;
}
.ap-h {
  margin: 0 0 0.9rem; font-family: var(--mono); font-weight: 600;
  font-size: 0.72rem; letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--teal-ink);
}
.ap-list { list-style: none; margin: 0; padding: 0; font-size: 0.95rem; color: var(--ink-70); }
.ap-list li {
  padding: 0.55rem 0;
  background-image: linear-gradient(to right, var(--rule) 45%, transparent 0);
  background-position: bottom; background-size: 6px 1px; background-repeat: repeat-x;
}
.ap-list li:last-child { background: none; }
.ap-ref {
  display: inline-block; min-width: 3.4rem; font-family: var(--mono);
  font-size: 0.72rem; color: var(--teal-ink); font-weight: 600;
}
.ap-source { margin-top: clamp(2rem, 5vw, 3.4rem); }
.src-cite { max-width: 42rem; font-size: 0.98rem; color: var(--ink); }
.src-note {
  max-width: 42rem; font-family: var(--mono); font-size: 0.76rem;
  line-height: 1.6; color: var(--ink-45); margin: 0.9rem 0;
}
.src-link { font-family: var(--mono); font-size: 0.78rem; color: var(--ink-70); }

/* ============================================================
   COLOPHON
   ============================================================ */
.colophon {
  background: var(--ink); color: var(--paper);
  padding: clamp(2.6rem, 6vw, 4.4rem) clamp(1.6rem, 4vw, 3.4rem);
}
.colo-grid {
  width: min(1180px, 100%); margin: 0 auto;
  display: grid; grid-template-columns: auto 1fr; gap: 0.7rem 2.4rem;
  align-items: baseline;
}
.colo-mark {
  grid-row: span 2; margin: 0; font-family: var(--serif); font-weight: 500;
  font-size: clamp(1.4rem, 3vw, 2rem); letter-spacing: 0.16em; color: var(--paper);
}
.colo-set { margin: 0; max-width: 44rem; font-family: var(--mono); font-size: 0.78rem; line-height: 1.6; color: color-mix(in srgb, var(--paper) 66%, transparent); }
.colo-credit { margin: 0; font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.06em; color: color-mix(in srgb, var(--paper) 60%, transparent); }
.colo-guide { margin: 0; font-family: var(--mono); font-size: 0.8rem; }
.colo-guide a { color: var(--teal); }
.colo-guide a:hover { color: var(--paper); }

/* ============================================================
   REVEAL (JS adds .reveal; reduced-motion path never hides)
   ============================================================ */
.reveal { opacity: 0; transform: translateY(18px); }
.is-in { opacity: 1; transform: none; transition: opacity 0.8s var(--ease), transform 0.8s var(--ease); }

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 900px) {
  .plate, .appendix {
    grid-template-columns: 1fr; row-gap: 1.6rem;
  }
  .col-side { display: flex; flex-wrap: wrap; align-items: baseline; gap: 0.4rem 1.2rem; }
  .fig-no { margin-bottom: 0; }
  .margin { flex-basis: 100%; max-width: 40rem; margin-top: 0.6rem;
    display: grid; grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); gap: 0.6rem 2rem; }
  .margin p { margin-bottom: 0; }
  .phase-dial { order: -1; }
}
@media (max-width: 680px) {
  .mast-grid {
    grid-template-areas: "word" "kicker" "body" "meta" "cue";
    grid-template-columns: 1fr;
  }
  .mast-meta { justify-self: stretch; }
  .kicker { font-size: 0.66rem; }
  .ghost-num { font-size: 34vw; right: -0.2rem; bottom: 2rem; }
  .chart-wrap { aspect-ratio: 4 / 3.4; }
  .colo-grid { grid-template-columns: 1fr; }
  .colo-mark { grid-row: auto; }
  .margin { grid-template-columns: 1fr; }
}

/* ============================================================
   PHASE DIAL (marginalia instrument diagram)
   ============================================================ */
.phase-dial { width: 100%; max-width: 9.5rem; color: var(--teal); margin-bottom: 1.1rem; }
.dial-peak { fill: var(--blue); }
.dial-trough { fill: var(--teal); }

/* ============================================================
   REDUCED MOTION
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  .reveal, .is-in { opacity: 1 !important; transform: none !important; transition: none !important; }
  .scroll-cue span { animation: none; }
  * { scroll-behavior: auto !important; }
}

/* ============================================================
   PRINT — good enough to actually print
   ============================================================ */
@media print {
  :root { --paper: #fff; }
  body { background: #fff; font-size: 10.5pt; line-height: 1.4; }
  .grain, .plate-rings, .scroll-cue, .ghost-num, .colo-guide { display: none !important; }
  .reveal { opacity: 1 !important; transform: none !important; }
  .masthead { min-height: 0; page-break-after: always; }
  .plate, .appendix { break-inside: avoid; page-break-inside: avoid; }
  .figure { break-inside: avoid; }
  .plate--ii, .plate--felt, .appendix, .colophon { background: #fff !important; color: #000 !important; }
  .colophon { border-top: 2px solid #000; }
  .colo-set, .colo-credit, .colo-mark { color: #000 !important; }
  a { color: #000; }
}