/* ==========================================================================
   Slate & Sum — chalkboard sheet.
   Deep slate ground, chalk-white rule work, one ochre accent, cool grey for
   secondary marks. Nothing is rounded, nothing floats, nothing casts a
   shadow: every separation is a 1px line, as on a ruled board.
   ========================================================================== */

:root {
  --slate-board: #1b2a2f;
  --slate-board-2: #22343a;
  --slate-board-3: #2a3d44;
  --slate-chalk: #ede7da;
  --slate-chalk-dim: #b9b3a6;
  --slate-ochre: #e4b363;
  --slate-cool: #6c8a8f;
  --slate-line: rgba(237, 231, 218, 0.24);
  --slate-line-soft: rgba(237, 231, 218, 0.12);
  --slate-rule: 1px;

  --slate-display: 'Bodoni Moda', 'Didot', 'Bodoni MT', Georgia, 'Times New Roman', serif;
  --slate-mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, 'Courier New', monospace;

  --rail-w: 74px;
  --measure: 46rem;
  --gutter: 4.5rem;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background-color: var(--slate-board);
  background-image:
    repeating-linear-gradient(0deg, rgba(237, 231, 218, 0.018) 0 1px, transparent 1px 3px),
    radial-gradient(120% 90% at 12% 0%, rgba(108, 138, 143, 0.16), transparent 60%);
  color: var(--slate-chalk);
  font-family: var(--slate-mono);
  font-size: 15px;
  line-height: 1.72;
  letter-spacing: 0.005em;
}

img { max-width: 100%; height: auto; display: block; }

a { color: var(--slate-chalk); text-decoration: none; border-bottom: 1px solid var(--slate-line); }
a:hover { color: var(--slate-ochre); border-bottom-color: var(--slate-ochre); }

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

.skip {
  position: absolute; left: -9999px; top: 0;
  background: var(--slate-ochre); color: var(--slate-board);
  padding: 10px 16px; z-index: 50; border: 0;
}
.skip:focus { left: 8px; top: 8px; }

/* --------------------------------------------------------------- the rail */
.rail {
  position: fixed;
  inset: 0 auto 0 0;
  width: var(--rail-w);
  border-right: var(--slate-rule) solid var(--slate-line);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 18px 0 18px;
  gap: 22px;
  background: rgba(20, 32, 36, 0.72);
  z-index: 20;
}

.rail-mark {
  writing-mode: vertical-rl;
  text-orientation: mixed;
  font-family: var(--slate-display);
  font-size: 17px;
  letter-spacing: 0.34em;
  text-transform: uppercase;
  color: var(--slate-chalk);
  border-bottom: 0;
  padding: 4px 0;
}
.rail-mark:hover { color: var(--slate-ochre); }

.rail-nav { display: flex; flex-direction: column; gap: 18px; align-items: center; margin-top: 6px; }

.rail-tier {
  display: flex; flex-direction: column; align-items: center; gap: 7px;
  border-bottom: 0; padding: 2px 0;
}
.rail-dot {
  width: 52px; height: 24px;
  border: var(--slate-rule) solid var(--slate-line);
  display: grid; place-items: center;
  font-family: var(--slate-mono); font-size: 7px; line-height: 1; letter-spacing: 0;
  color: var(--slate-chalk-dim);
}
.rail-tier[data-tier="warm-up"] .rail-dot { color: var(--slate-cool); }
.rail-tier[data-tier="core"] .rail-dot { color: var(--slate-chalk); }
.rail-tier[data-tier="olympiad"] .rail-dot { color: var(--slate-ochre); }
.rail-tier:hover .rail-dot, .rail-tier[aria-current="page"] .rail-dot {
  border-color: var(--slate-ochre); color: var(--slate-ochre);
}
.rail-tier[aria-current="page"] .rail-dot::after { content: ''; }
.rail-word {
  writing-mode: vertical-rl;
  font-size: 9.5px; letter-spacing: 0.22em; text-transform: uppercase;
  color: var(--slate-chalk-dim);
}
.rail-tier:hover .rail-word { color: var(--slate-chalk); }

.rail-spacer { flex: 1; }

.rail-util {
  writing-mode: vertical-rl;
  font-size: 10px; letter-spacing: 0.2em; text-transform: uppercase;
  color: var(--slate-cool); border-bottom: 0;
}
.rail-util:hover { color: var(--slate-ochre); }
.rail-util[aria-current="page"] { color: var(--slate-ochre); }

/* -------------------------------------------------------------- the sheet */
.sheet {
  margin-left: var(--rail-w);
  padding: 0 var(--gutter) 0;
  max-width: calc(var(--measure) + var(--gutter) * 2);
}

.rule { border: 0; border-top: var(--slate-rule) solid var(--slate-line); margin: 0; }
.rule-soft { border: 0; border-top: var(--slate-rule) solid var(--slate-line-soft); margin: 0; }

.langswap {
  display: flex; justify-content: flex-end; gap: 14px;
  padding: 14px 0 0;
  font-size: 10.5px; letter-spacing: 0.18em; text-transform: uppercase;
}
.langswap a { border-bottom: 0; color: var(--slate-cool); }
.langswap a:hover { color: var(--slate-ochre); }
.langswap .sep { color: var(--slate-line); }

/* ------------------------------------------------------------- the cover */
.cover { padding: 3.4rem 0 2.2rem; }
.cover-kicker {
  margin: 0 0 1.1rem;
  font-size: 10.5px; letter-spacing: 0.42em; text-transform: uppercase;
  color: var(--slate-cool);
}
.cover-masthead {
  font-family: var(--slate-display);
  font-weight: 400;
  font-size: clamp(3.2rem, 11vw, 6.4rem);
  line-height: 0.92;
  letter-spacing: -0.015em;
  margin: 0 0 0.5rem;
}
.cover-masthead .amp { color: var(--slate-ochre); font-style: italic; }
.cover-tagline {
  font-family: var(--slate-display);
  font-size: clamp(1.05rem, 2.6vw, 1.5rem);
  font-style: italic;
  color: var(--slate-chalk-dim);
  margin: 0 0 1.6rem;
  max-width: 34rem;
}
.cover-meta {
  display: flex; flex-wrap: wrap; gap: 0 22px;
  font-size: 10.5px; letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--slate-cool);
  border-top: var(--slate-rule) solid var(--slate-line);
  padding-top: 12px; margin: 0;
}

/* --------------------------------------------------------- the big row */
.sec-head {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: 18px; margin: 3.2rem 0 0; padding-bottom: 9px;
  border-bottom: var(--slate-rule) solid var(--slate-line);
}
.sec-head h2 {
  font-family: var(--slate-display); font-weight: 400;
  font-size: 1.5rem; letter-spacing: 0.03em; margin: 0;
}
.sec-head .sec-note {
  font-size: 10px; letter-spacing: 0.2em; text-transform: uppercase; color: var(--slate-cool);
}

/* The five problems of the current issue, laid out as a single ruled row of
   very large numerals. No boxes, no thumbnails — the number is the ornament. */
.issue {
  list-style: none; margin: 0; padding: 0;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  border-bottom: var(--slate-rule) solid var(--slate-line);
}
.issue-row { border-right: var(--slate-rule) solid var(--slate-line-soft); }
.issue-row:last-child { border-right: 0; }
.issue-row a {
  display: block;
  padding: 1.5rem 1.1rem 1.3rem;
  border-bottom: 0;
  height: 100%;
}
.issue-row:first-child a { padding-left: 0; }
.issue-no {
  display: block;
  font-family: var(--slate-display);
  font-size: clamp(2.9rem, 6.4vw, 4.6rem);
  line-height: 0.78;
  letter-spacing: -0.02em;
  color: var(--slate-ochre);
  margin-bottom: 0.85rem;
}
.issue-row a:hover .issue-no { color: var(--slate-chalk); }
.issue-title {
  display: block;
  font-family: var(--slate-display);
  font-size: clamp(0.98rem, 1.6vw, 1.12rem);
  line-height: 1.3;
  margin-bottom: 0.7rem;
}
.issue-row a:hover .issue-title { color: var(--slate-ochre); }
.issue-row .dots { display: block; }

.dots { color: var(--slate-cool); letter-spacing: 0.22em; font-size: 11px; white-space: nowrap; }
.issue-row[data-tier="olympiad"] .dots { color: var(--slate-ochre); }
.issue-row[data-tier="core"] .dots { color: var(--slate-chalk); }

/* ------------------------------------------------------ tier listing pages */
.tier-list { list-style: none; margin: 2.2rem 0 0; padding: 0; }
.tier-item { border-bottom: var(--slate-rule) solid var(--slate-line-soft); }
.tier-item a {
  display: grid;
  grid-template-columns: 12rem 2.6rem 1fr auto;
  align-items: center; gap: 0 1rem;
  padding: 0.85rem 0;
  border-bottom: 0;
}
.tier-thumb { width: 12rem; border: var(--slate-rule) solid var(--slate-line-soft); }
.tier-item .ti-no { font-size: 11px; color: var(--slate-cool); }
.tier-item .ti-t { font-family: var(--slate-display); font-size: 1.12rem; line-height: 1.3; }
.tier-item a:hover .ti-t { color: var(--slate-ochre); }
.tier-item .ti-date { font-size: 10.5px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--slate-cool); }

/* --------------------------------------------------------- tier ledger */
.ledger { margin-top: 2.6rem; }
.ledger-h {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: 16px; padding-bottom: 8px;
  border-bottom: var(--slate-rule) solid var(--slate-line);
}
.ledger-h h3 {
  font-family: var(--slate-display); font-weight: 400;
  font-size: 1.22rem; margin: 0; letter-spacing: 0.04em;
}
.ledger-h .ledger-count { font-size: 10px; letter-spacing: 0.2em; text-transform: uppercase; color: var(--slate-cool); }
.ledger-blurb { color: var(--slate-chalk-dim); font-size: 13px; margin: 10px 0 4px; max-width: 38rem; }

.ledger-list { list-style: none; margin: 0; padding: 0; }
.ledger-item { border-bottom: var(--slate-rule) solid var(--slate-line-soft); }
.ledger-item a {
  display: grid;
  grid-template-columns: 2.6rem 1fr auto;
  align-items: baseline; gap: 0 0.9rem;
  padding: 0.62rem 0;
  border-bottom: 0;
}
.ledger-item .li-no { font-family: var(--slate-mono); font-size: 11px; color: var(--slate-cool); }
.ledger-item .li-t { font-family: var(--slate-display); font-size: 1.02rem; }
.ledger-item a:hover .li-t { color: var(--slate-ochre); }
.ledger-more { margin: 12px 0 0; font-size: 11px; letter-spacing: 0.16em; text-transform: uppercase; }
.ledger-more a { color: var(--slate-cool); border-bottom: 0; }
.ledger-more a:hover { color: var(--slate-ochre); }

/* ------------------------------------------------------------ past issues */
.past { margin: 3.4rem 0 0; padding-bottom: 3rem; }
.past-index { font-size: 12.5px; line-height: 2.1; color: var(--slate-chalk-dim); }
.past-index a { border-bottom: 0; color: var(--slate-chalk-dim); }
.past-index a:hover { color: var(--slate-ochre); }
.past-index .sep { color: rgba(237, 231, 218, 0.28); padding: 0 7px; }

/* ------------------------------------------------------------- the footer */
.foot {
  margin-left: var(--rail-w);
  border-top: var(--slate-rule) solid var(--slate-line);
  padding: 1.6rem var(--gutter) 3.4rem;
  max-width: calc(var(--measure) + var(--gutter) * 2);
  display: flex; flex-wrap: wrap; gap: 10px 26px;
  font-size: 10.5px; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--slate-cool);
}
.foot a { color: var(--slate-cool); border-bottom: 0; }
.foot a:hover { color: var(--slate-ochre); }
.foot .foot-spacer { flex: 1; }
.foot .foot-note { letter-spacing: 0.04em; text-transform: none; color: rgba(108, 138, 143, 0.9); font-size: 11.5px; }
/* The editorial disclaimer reads as prose, on its own line below the links. */
.foot .foot-disclaimer {
  flex-basis: 100%; order: 9; max-width: 68ch;
  letter-spacing: 0.02em; text-transform: none; line-height: 1.6;
  color: rgba(108, 138, 143, 0.72); font-size: 11px;
  border-top: var(--slate-rule) solid var(--slate-line); padding-top: 10px;
}

/* -------------------------------------------------------------- page heads */
.page-head { padding: 2.6rem 0 0; }
.page-head .ph-back {
  display: inline-block; font-size: 10.5px; letter-spacing: 0.18em; text-transform: uppercase;
  color: var(--slate-cool); border-bottom: 0; margin-bottom: 1.4rem;
}
.page-head .ph-back:hover { color: var(--slate-ochre); }
.page-head h1 {
  font-family: var(--slate-display); font-weight: 400;
  font-size: clamp(2rem, 6vw, 3.2rem); line-height: 1.05;
  margin: 0 0 0.7rem; letter-spacing: -0.01em;
}
.page-head .ph-lead { font-family: var(--slate-display); font-style: italic; color: var(--slate-chalk-dim); font-size: 1.1rem; margin: 0 0 1.2rem; max-width: 36rem; }
.page-head .ph-meta {
  display: flex; flex-wrap: wrap; gap: 6px 20px;
  font-size: 10.5px; letter-spacing: 0.16em; text-transform: uppercase; color: var(--slate-cool);
  border-top: var(--slate-rule) solid var(--slate-line); padding-top: 11px; margin: 0;
}
/* The signing desk sits in the meta line beside the release date. */
.page-head .ph-meta .byline { color: var(--slate-chalk-dim); letter-spacing: 0.14em; }

/* ------------------------------------------------------------ the puzzle */
.puzzle { padding-bottom: 1rem; }

.block-figure { margin: 1.8rem 0 0; border: var(--slate-rule) solid var(--slate-line); }
.block-figure img { width: 100%; }
.block-figure figcaption {
  font-size: 10px; letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--slate-cool); padding: 8px 10px; border-top: var(--slate-rule) solid var(--slate-line);
}

.statement {
  background: var(--slate-board-3);
  border: var(--slate-rule) solid var(--slate-line);
  padding: 1.6rem 1.7rem 1.4rem;
  margin-top: 1.8rem;
}
.statement .label {
  font-size: 10px; letter-spacing: 0.26em; text-transform: uppercase;
  color: var(--slate-ochre); margin: 0 0 0.9rem;
}
.statement .prompt { font-size: 16.5px; line-height: 1.85; margin: 0; }
.statement .prompt p { margin: 0 0 0.9rem; }
.statement .prompt p:last-child { margin-bottom: 0; }

.constraints { list-style: none; margin: 1.3rem 0 0; padding: 1rem 0 0; border-top: var(--slate-rule) solid var(--slate-line-soft); }
.constraints li { display: grid; grid-template-columns: 1.4rem 1fr; gap: 0 0.6rem; font-size: 13.5px; color: var(--slate-chalk-dim); padding: 3px 0; }
.constraints li::before { content: '—'; color: var(--slate-cool); }

.thinking { padding: 2.4rem 0 1.2rem; }
.thinking .label {
  font-size: 10px; letter-spacing: 0.26em; text-transform: uppercase;
  color: var(--slate-cool); margin: 0 0 1rem;
}

.hint { border: var(--slate-rule) solid var(--slate-line); margin-bottom: 10px; background: transparent; }
.hint > summary {
  cursor: pointer; list-style: none;
  padding: 11px 14px;
  font-size: 11px; letter-spacing: 0.2em; text-transform: uppercase; color: var(--slate-chalk-dim);
  display: flex; justify-content: space-between; gap: 12px;
}
.hint > summary::-webkit-details-marker { display: none; }
.hint > summary::after { content: '+'; color: var(--slate-ochre); font-size: 14px; line-height: 1; }
.hint[open] > summary::after { content: '–'; }
.hint[open] > summary { border-bottom: var(--slate-rule) solid var(--slate-line-soft); color: var(--slate-chalk); }
.hint .hint-body { padding: 14px; font-size: 14.5px; line-height: 1.8; color: var(--slate-chalk); }
.hint .hint-body p { margin: 0; }

.solution { border-top: var(--slate-rule) solid var(--slate-line); padding-top: 1.6rem; margin-top: 1.2rem; }
.solution h2 {
  font-family: var(--slate-display); font-weight: 400; font-size: 1.7rem;
  margin: 0 0 1rem; letter-spacing: 0.02em;
}
.answer {
  border-left: 3px solid var(--slate-ochre);
  padding: 2px 0 2px 16px;
  margin: 0 0 1.8rem;
  font-size: 16px; line-height: 1.8;
}
.answer .label {
  display: block; font-size: 10px; letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--slate-ochre); margin-bottom: 5px;
}

.two-col { display: grid; grid-template-columns: minmax(0, 1.9fr) minmax(0, 1fr); gap: 0 2rem; align-items: start; }
.col-label {
  font-size: 10px; letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--slate-cool); margin: 0 0 1rem; padding-bottom: 7px;
  border-bottom: var(--slate-rule) solid var(--slate-line-soft);
}

.steps { list-style: none; counter-reset: st; margin: 0; padding: 0; }
.steps > li {
  counter-increment: st;
  display: grid; grid-template-columns: 2.1rem 1fr; gap: 0 0.9rem;
  padding: 0 0 1.5rem;
  position: relative;
}
.steps > li::before {
  content: counter(st, decimal-leading-zero);
  font-size: 10.5px; letter-spacing: 0.1em; color: var(--slate-ochre); padding-top: 4px;
}
.steps > li .step { margin: 0; font-size: 14.5px; line-height: 1.8; }
.steps > li .note {
  margin: 7px 0 0; font-size: 12.5px; line-height: 1.7; color: var(--slate-chalk-dim);
  border-left: var(--slate-rule) solid var(--slate-line-soft); padding-left: 12px;
}

.margin-notes {
  border-left: var(--slate-rule) solid var(--slate-line);
  padding-left: 1.5rem;
}
.margin-notes ol { list-style: none; counter-reset: mn; margin: 0; padding: 0; }
.margin-notes li {
  counter-increment: mn; font-size: 12.5px; line-height: 1.75; color: var(--slate-chalk-dim);
  padding: 0 0 1.05rem;
}
.margin-notes li::before { content: '¶ ' counter(mn); color: var(--slate-cool); display: block; font-size: 10px; letter-spacing: 0.14em; }

.tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 2rem 0 0; }
.tags a {
  font-size: 10.5px; letter-spacing: 0.12em; text-transform: uppercase;
  border: var(--slate-rule) solid var(--slate-line); padding: 4px 9px; color: var(--slate-chalk-dim); border-bottom: 1px solid var(--slate-line);
}
.tags a:hover { border-color: var(--slate-ochre); color: var(--slate-ochre); }

.related { margin: 3rem 0 0; }
.related-row { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0; border-top: var(--slate-rule) solid var(--slate-line); }
.related-item { padding: 1.1rem 1.2rem 1.2rem 0; border-right: var(--slate-rule) solid var(--slate-line-soft); }
.related-item:last-child { border-right: 0; padding-right: 0; }
.related-item:not(:first-child) { padding-left: 1.2rem; }
.related-item .ri-no { font-size: 10px; letter-spacing: 0.16em; color: var(--slate-cool); display: block; margin-bottom: 7px; }
.related-item .ri-t { font-family: var(--slate-display); font-size: 1.02rem; line-height: 1.35; display: block; border-bottom: 0; }
.related-item a:hover .ri-t { color: var(--slate-ochre); }

.prevnext { display: flex; justify-content: space-between; gap: 20px; margin-top: 2.4rem; padding-top: 1.1rem; border-top: var(--slate-rule) solid var(--slate-line-soft); font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase; }
.prevnext a { color: var(--slate-cool); border-bottom: 0; }
.prevnext a:hover { color: var(--slate-ochre); }
.prevnext .pn-next { text-align: right; margin-left: auto; }

/* ------------------------------------------------------------- the archive */
.archive-month { margin-top: 2.4rem; }
.archive-month h2 {
  font-family: var(--slate-mono); font-weight: 400; font-size: 11px;
  letter-spacing: 0.26em; text-transform: uppercase; color: var(--slate-cool);
  margin: 0 0 0; padding-bottom: 8px; border-bottom: var(--slate-rule) solid var(--slate-line);
}
.archive-list { list-style: none; margin: 0; padding: 0; }
.archive-list li { border-bottom: var(--slate-rule) solid var(--slate-line-soft); }
.archive-list li > a {
  display: grid;
  grid-template-columns: 2.6rem 6.6rem 1fr auto;
  gap: 0 0.9rem; align-items: baseline;
  padding: 0.6rem 0;
  border-bottom: 0;
}
.archive-list .a-no { font-size: 11px; color: var(--slate-cool); }
.archive-list .a-date { font-size: 11px; color: var(--slate-cool); }
.archive-list .a-t { font-family: var(--slate-display); font-size: 1.02rem; }
.archive-list a:hover .a-t { color: var(--slate-ochre); }

/* ------------------------------------------------------------ the glossary */
.term { border-top: var(--slate-rule) solid var(--slate-line); padding: 1.5rem 0 1.6rem; }
.term h2 { font-family: var(--slate-display); font-weight: 400; font-size: 1.5rem; margin: 0 0 0.6rem; }
.term .def { margin: 0 0 0.9rem; font-size: 14.5px; line-height: 1.8; }
.term .ex, .term .watch { font-size: 13px; line-height: 1.75; color: var(--slate-chalk-dim); margin: 0 0 0.6rem; padding-left: 1.1rem; border-left: var(--slate-rule) solid var(--slate-line-soft); }
.term .ex b, .term .watch b { color: var(--slate-cool); font-weight: 400; text-transform: uppercase; letter-spacing: 0.14em; font-size: 10px; display: block; margin-bottom: 3px; }

/* ---------------------------------------------------------------- the legal */
.legal { padding-bottom: 1rem; }
.legal section { border-top: var(--slate-rule) solid var(--slate-line); padding: 1.5rem 0 0.6rem; margin-top: 1.5rem; }
.legal h2 { font-family: var(--slate-display); font-weight: 400; font-size: 1.32rem; margin: 0 0 0.7rem; }
.legal p { margin: 0 0 0.95rem; font-size: 14px; line-height: 1.85; color: var(--slate-chalk); }
.legal ul { margin: 0 0 1rem; padding-left: 1.2rem; }
.legal li { font-size: 14px; line-height: 1.85; margin-bottom: 0.4rem; }
.legal .toc { list-style: none; padding: 0; margin: 1.6rem 0 0; display: flex; flex-wrap: wrap; gap: 6px 18px; font-size: 11px; letter-spacing: 0.1em; text-transform: uppercase; }
.legal .toc a { color: var(--slate-cool); border-bottom: 0; }
.legal .toc a:hover { color: var(--slate-ochre); }
.legal .updated { font-size: 11px; letter-spacing: 0.16em; text-transform: uppercase; color: var(--slate-cool); }

/* ----------------------------------------------------------------- maths */
.slate-math { vertical-align: -0.15em; }
.slate-math svg, svg.slate-math { display: inline-block; }
.slate-math-block { display: block; margin: 1.1rem 0; overflow-x: auto; }
.slate-math-block svg { max-width: 100%; }
svg.slate-math { color: var(--slate-chalk); }
svg.slate-math * { color: inherit; }
.slate-tex-error { color: var(--slate-ochre); border: 1px dashed var(--slate-ochre); padding: 1px 5px; font-size: 12px; }

/* -------------------------------------------------------------- not found */
.notfound { padding: 5rem 0 4rem; }
.notfound h1 { font-family: var(--slate-display); font-weight: 400; font-size: clamp(2.4rem, 8vw, 4.4rem); margin: 0 0 1rem; }
.notfound p { color: var(--slate-chalk-dim); max-width: 32rem; }

/* --------------------------------------------------------------- narrow */
@media (max-width: 900px) {
  :root { --gutter: 1.5rem; }

  body { font-size: 14.5px; }

  .rail {
    inset: auto 0 0 0;
    width: auto; height: 58px;
    flex-direction: row; justify-content: space-around; align-items: center;
    border-right: 0; border-top: var(--slate-rule) solid var(--slate-line);
    padding: 0 8px; gap: 0;
    background: rgba(20, 32, 36, 0.94);
  }
  .rail-mark { writing-mode: horizontal-tb; font-size: 13px; letter-spacing: 0.2em; }
  .rail-nav { flex-direction: row; gap: 14px; margin-top: 0; }
  .rail-tier { flex-direction: row; gap: 6px; }
  .rail-dot { width: 26px; height: 26px; font-size: 9px; }
  .rail-word { writing-mode: horizontal-tb; font-size: 9px; letter-spacing: 0.12em; }
  .rail-spacer { display: none; }
  .rail-util { writing-mode: horizontal-tb; font-size: 9px; letter-spacing: 0.12em; }

  .sheet, .foot { margin-left: 0; }
  .foot { padding-bottom: 5.5rem; }

  .issue { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .issue-row { border-bottom: var(--slate-rule) solid var(--slate-line-soft); }
  .issue-row:nth-child(2n) { border-right: 0; }
  .issue-row a, .issue-row:first-child a { padding: 1.2rem 1rem; }
  .issue-row:first-child a { padding-left: 0; }
  .tier-item a { grid-template-columns: 2.4rem 1fr; gap: 0 0.8rem; }
  .tier-thumb { display: none; }
  .tier-item .ti-date { display: none; }
  .two-col { grid-template-columns: minmax(0, 1fr); gap: 1.6rem 0; }
  .margin-notes { border-left: 0; padding-left: 0; border-top: var(--slate-rule) solid var(--slate-line); padding-top: 1.4rem; }
  .related-row { grid-template-columns: minmax(0, 1fr); }
  .related-item { border-right: 0; padding: 1rem 0 1.1rem; border-bottom: var(--slate-rule) solid var(--slate-line-soft); }
  .related-item:not(:first-child) { padding-left: 0; }
  .archive-list li > a { grid-template-columns: 2.4rem 1fr auto; }
  .archive-list .a-date { display: none; }
  .rail-dot { width: 40px; height: 20px; font-size: 6px; }
  .cover { padding-top: 2.2rem; }
}

@media print {
  .rail, .langswap, .foot { display: none; }
  body { background: #fff; color: #111; }
  .sheet { margin: 0; }
}