/* ============================================================
   5ac.vn — /papers (C2 "Reading edition", t_b87404b3)
   Locked reference: /root/5ac/research/papers-hub-concept/shots/
     c2-hub-1440x900.png        sha256 f102e965…b5a492
     c2-hub-390x844.png         sha256 413e5810…960a   (Moken 02/11/2026)
     c2-collection-1440x900.png sha256 38741bc6…a54bbc
     c2-collection-390x844.png  sha256 538b9abe…92b1b21
     c2-paper-1440x900.png      sha256 ab73637b…584040e
     c2-paper-390x844.png       sha256 d9df7ebb…316873a2

   TOKEN DISCIPLINE (design.md §"Use the published token API"):
   every colour, type role, spacing, radius, shadow and motion value reads a
   --5ac-* token. The four page-scoped values below are NOT published tokens —
   they are decisions this page owns, declared here once (carve-out P3) and
   never re-declared anywhere else:
     --papers-measure          680px  owner-approved deviation from the C2
                                     reference's 734px (CEO comment 02/11/2026)
     --papers-read-max         1200px 3-column reading grid (150|680|200 + gaps)
     --papers-toc-w / -sn-w    150 / 200px  TOC and sidenote columns
     --papers-apply-border     gold block border — --5ac-color-separator is
                                     invisible on the highlight surface
     --papers-on-highlight[.muted] ink on --5ac-color-highlight; the semantic
                                     label tokens flip light in dark mode and
                                     would drop to ~1.4:1 on the gold block
   FONT SIZE: rem only — a single `font-size: Npx` in this file would cost the
   TYPO -4 tier in score-page.py, and 16px = 1rem exactly.
   SPACING: every margin/padding is a multiple of 4px — the instrument's 4px-grid
   probe measures margin/padding on every rendered element.
   MIN UI FONT: 12px floor (badges may be 11px); the mockup's 9.5–11.5px text
   was annotation layer, not UI.
   ============================================================ */

:root {
  --papers-measure: 680px;
  --papers-read-max: 1200px;
  --papers-toc-w: 150px;
  --papers-sn-w: 200px;
  --papers-apply-border: #e6d3a5;
  --papers-on-highlight: #141413;
  --papers-on-highlight-muted: #57554e;
}

/* ─── shared shell ─────────────────────────────────────── */
.pp-wrap {
  max-width: var(--5ac-layout-container-max);
  margin: 0 auto;
  padding: 0 var(--5ac-space-xl);
  width: 100%;
}

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

/* ─── hero ─────────────────────────────────────────────── */
.pp-hero {
  padding: 52px 0 8px;
}
.pp-h1 {
  font-size: var(--5ac-type-large-title-font-size);
  line-height: var(--5ac-type-large-title-line-height);
  font-weight: var(--5ac-type-large-title-font-weight);
  letter-spacing: -0.015em;
  margin: 0;
  max-width: 820px;
}
.pp-lede {
  font-size: 1.1875rem;
  line-height: 1.5;
  color: var(--5ac-color-label-secondary);
  max-width: 640px;
  margin: 16px 0 0;
}
.pp-hero--tight {
  padding-top: 12px;
}
.pp-hero-meta {
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  margin-top: 16px;
  font-variant-numeric: tabular-nums;
}
.pp-hero-cta {
  display: flex;
  gap: var(--5ac-space-xl);
  align-items: center;
  margin-top: 24px;
  flex-wrap: wrap;
}
.pp-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: var(--5ac-accessibility-min-touch-target);
  min-width: var(--5ac-accessibility-min-touch-target);
  padding: 0 var(--5ac-space-lg);
  background: var(--5ac-color-accent);
  color: var(--5ac-color-on-accent);
  border-radius: var(--5ac-radius-pill);
  font-size: 0.90625rem;
  font-weight: 600;
  text-decoration: none;
}
.pp-tlink {
  display: inline-flex;
  align-items: center;
  min-height: var(--5ac-accessibility-min-touch-target);
  min-width: var(--5ac-accessibility-min-touch-target);
  font-size: 0.9375rem;
  color: var(--5ac-color-link);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}
@media (hover: hover) and (pointer: fine) {
  .pp-btn:hover {
    background: var(--5ac-color-accent-hover);
    color: var(--5ac-color-on-accent);
    text-decoration: none;
  }
  .pp-tlink:hover {
    color: var(--5ac-color-accent-hover);
  }
}

/* ─── breadcrumb ───────────────────────────────────────── */
.pp-crumb {
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  margin-top: 32px;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0 4px;
}
.pp-crumb a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: var(--5ac-accessibility-min-touch-target);
  min-width: var(--5ac-accessibility-min-touch-target);
  color: var(--5ac-color-label-secondary);
  text-decoration: underline;
  text-underline-offset: 2px;
}
@media (hover: hover) and (pointer: fine) {
  .pp-crumb a:hover {
    color: var(--5ac-color-accent-hover);
  }
}

/* ─── section head (Collection / Tìm nhanh) ────────────── */
.pp-sec-head {
  display: flex;
  align-items: baseline;
  gap: var(--5ac-space-sm);
  margin: 48px 0 16px;
  flex-wrap: wrap;
}
.pp-sec-head h2 {
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0;
}
.pp-sec-head .n {
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  font-variant-numeric: tabular-nums;
}
.pp-sec-head .sub {
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  margin-left: auto;
}

/* ─── collection index block (Scope §1, hairline mục lục) ─ */
.pp-coll-idx {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 44px;
  border-top: 1px solid var(--5ac-color-separator);
}
/* One real collection → the index reads as a single full-width row instead of
   a half-filled 2-column grid (the 2-col geometry only exists at ≥2 entries;
   placeholders are never shipped, so the block degrades honestly). */
.pp-coll-idx--single {
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
}
/* keep the description line inside the prose measure when the row is full width */
.pp-coll-idx--single .pp-ce-p {
  max-width: var(--5ac-layout-prose-max);
}
.pp-ce {
  display: block;
  padding: 16px 0;
  border-bottom: 1px solid var(--5ac-color-separator);
  text-decoration: none;
  color: inherit;
}
.pp-ce-h {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  align-items: baseline;
}
.pp-ce-n {
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--5ac-color-label);
  letter-spacing: -0.006em;
}
.pp-ce-c {
  font-family: var(--5ac-font-mono);
  font-size: 0.78125rem;
  color: var(--5ac-color-label-secondary);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
.pp-ce-p {
  display: block;
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  margin: 8px 0 0;
  line-height: 1.45;
}
.pp-ce-f {
  margin-top: 8px;
  font-size: 0.78125rem;
  color: var(--5ac-color-label-secondary);
  display: flex;
  gap: var(--5ac-space-xs);
  align-items: center;
  flex-wrap: wrap;
}
.pp-tag-real {
  font-family: var(--5ac-font-mono);
  font-size: 0.6875rem;
  color: var(--5ac-color-label);
  border: 1px solid var(--5ac-status-success);
  border-radius: 4px;
  padding: 0 4px;
  white-space: nowrap;
}
@media (hover: hover) and (pointer: fine) {
  .pp-ce:hover {
    text-decoration: none;
  }
  .pp-ce:hover .pp-ce-n {
    color: var(--5ac-color-link);
  }
}

/* ─── toolbar + searchable combobox ────────────────────── */
.pp-toolbar {
  display: flex;
  gap: var(--5ac-space-md);
  align-items: flex-start;
  position: relative;
  z-index: 5;
}
.pp-combo {
  position: relative;
  width: 480px;
  max-width: 100%;
}
.pp-combo input {
  width: 100%;
  height: 46px;
  border: 1px solid var(--5ac-color-separator);
  border-radius: var(--5ac-radius-md);
  background: var(--5ac-color-background-secondary);
  padding: 0 64px 0 40px;
  font: 400 1rem/1 var(--5ac-font-sans);
  color: var(--5ac-color-label);
}
.pp-combo input::placeholder {
  color: var(--5ac-color-label-secondary);
}
.pp-combo input:focus-visible {
  outline: 2px solid var(--5ac-color-accent);
  outline-offset: 2px;
}
.pp-ico {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--5ac-color-label-secondary);
  display: flex;
  pointer-events: none;
}
.pp-kbd {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--5ac-font-mono);
  font-size: 0.75rem;
  color: var(--5ac-color-label-secondary);
  border: 1px solid var(--5ac-color-separator);
  border-radius: 4px;
  padding: 4px 8px;
  background: var(--5ac-color-background);
  pointer-events: none;
}
.pp-pop {
  position: absolute;
  top: 54px;
  left: 0;
  right: 0;
  background: var(--5ac-color-background);
  border: 1px solid var(--5ac-color-separator);
  border-radius: var(--5ac-radius-md);
  box-shadow: var(--5ac-shadow-2);
  padding: 12px;
  max-height: 270px;
  overflow-y: auto;
}
.pp-grp {
  font-size: 0.75rem;
  color: var(--5ac-color-label-secondary);
  margin: 8px 8px 4px;
}
.pp-grp:first-child {
  margin-top: 4px;
}
.pp-it {
  display: flex;
  justify-content: space-between;
  gap: var(--5ac-space-sm);
  padding: 8px;
  border-radius: 6px;
  font-size: 0.90625rem;
  color: var(--5ac-color-label);
  align-items: center;
  min-height: var(--5ac-accessibility-min-touch-target);
  cursor: pointer;
}
.pp-it .c {
  font-family: var(--5ac-font-mono);
  font-size: 0.75rem;
  color: var(--5ac-color-label-secondary);
  font-variant-numeric: tabular-nums;
}
.pp-it[aria-selected='true'] {
  background: var(--5ac-color-background-secondary);
}
@media (hover: hover) and (pointer: fine) {
  .pp-it:hover {
    background: var(--5ac-color-background-secondary);
  }
}
.pp-it.is-active {
  background: var(--5ac-color-background-secondary);
}
.pp-tb-meta {
  margin-left: auto;
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  align-self: center;
  text-align: right;
  max-width: 340px;
  font-variant-numeric: tabular-nums;
}

/* ─── list section + rows ──────────────────────────────── */
.pp-sec2 {
  display: flex;
  align-items: baseline;
  gap: var(--5ac-space-sm);
  margin: 44px 0 4px;
  border-bottom: 1px solid var(--5ac-color-separator);
  padding-bottom: 8px;
}
.pp-sec2 h2 {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0;
}
.pp-sec2 .n {
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  font-variant-numeric: tabular-nums;
}
.pp-sec2 .go {
  margin-left: auto;
  font-size: 0.84375rem;
  color: var(--5ac-color-link);
  display: inline-flex;
  align-items: center;
  justify-content: flex-end;
  min-height: var(--5ac-accessibility-min-touch-target);
  min-width: var(--5ac-accessibility-min-touch-target);
  text-decoration: none;
}
@media (hover: hover) and (pointer: fine) {
  .pp-sec2 .go:hover {
    color: var(--5ac-color-accent-hover);
    text-decoration: underline;
  }
}
.pp-row2 {
  display: block;
  padding: 16px 0;
  border-bottom: 1px solid var(--5ac-color-separator);
  text-decoration: none;
  color: inherit;
}
.pp-row2 .rt {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--5ac-color-label);
  letter-spacing: -0.008em;
  display: block;
}
.pp-lede2 {
  font-family: var(--5ac-font-serif);
  font-style: italic;
  font-size: 1.03125rem;
  line-height: 1.5;
  color: var(--5ac-color-label-secondary);
  margin: 8px 0 0;
  display: block;
}
.pp-rm2 {
  font-size: 0.84375rem;
  color: var(--5ac-color-label-secondary);
  margin-top: 8px;
  font-variant-numeric: tabular-nums;
  display: block;
}
@media (hover: hover) and (pointer: fine) {
  .pp-row2:hover {
    text-decoration: none;
  }
  .pp-row2:hover .rt {
    color: var(--5ac-color-link);
  }
}
.pp-empty {
  font-size: 0.9375rem;
  color: var(--5ac-color-label-secondary);
  padding: 24px 0;
  margin: 0;
}

/* ─── single paper: reading grid (TOC | measure | sidenote) ─ */
.pp-read {
  display: grid;
  grid-template-columns: var(--papers-toc-w) minmax(0, var(--papers-measure)) var(--papers-sn-w);
  gap: 26px;
  max-width: var(--papers-read-max);
  margin: 0 auto;
  padding: 0 var(--5ac-space-xl);
}
.pp-toc {
  position: sticky;
  top: calc(var(--5ac-layout-nav-height) + 24px);
  font-size: 0.84375rem;
  align-self: start;
}
.pp-toc-h {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--5ac-color-label-secondary);
  margin-bottom: 8px;
}
.pp-toc ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
.pp-toc li {
  margin: 0;
  color: var(--5ac-color-label-secondary);
}
.pp-toc a {
  display: flex;
  gap: var(--5ac-space-xs);
  align-items: center;
  min-height: var(--5ac-accessibility-min-touch-target);
  color: inherit;
  text-decoration: none;
}
.pp-toc .num {
  font-family: var(--5ac-font-mono);
  font-size: 0.75rem;
  color: var(--5ac-color-label-secondary);
}
.pp-toc li.on,
.pp-toc li.on .num {
  color: var(--5ac-color-link);
  font-weight: 600;
}
@media (hover: hover) and (pointer: fine) {
  .pp-toc a:hover {
    color: var(--5ac-color-link);
    text-decoration: none;
  }
}

.pp-article {
  min-width: 0;
}
.pp-title {
  font-size: clamp(2rem, 4vw, 2.75rem);
  line-height: 1.1;
  font-weight: 600;
  letter-spacing: -0.014em;
  margin: 16px 0 0;
  max-width: 900px;
}
.pp-dek {
  font-size: 1.1875rem;
  line-height: 1.5;
  color: var(--5ac-color-label);
  margin: 16px 0 0;
  max-width: 640px;
}
.pp-abstract {
  font-family: var(--5ac-font-serif);
  font-style: italic;
  font-size: 1.125rem;
  line-height: 1.6;
  color: var(--5ac-color-label-secondary);
  margin-top: 16px;
}
.pp-pmeta {
  font-size: 0.90625rem;
  color: var(--5ac-color-label-secondary);
  margin-top: 16px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--5ac-color-separator);
  line-height: 1.6;
  font-variant-numeric: tabular-nums;
}
.pp-pmeta .mono {
  font-family: var(--5ac-font-mono);
  font-size: 0.84375rem;
}

.pp-article > section > h2 {
  font-size: 1.375rem;
  letter-spacing: -0.01em;
  margin: 40px 0 16px;
  scroll-margin-top: 96px;
}
.pp-article p {
  margin: 0 0 16px;
  font-size: 1.0625rem;
  line-height: 1.6;
}
.pp-article ul,
.pp-article ol {
  padding-left: var(--5ac-space-xl);
}

/* numbered findings — the authored <ol> lands straight in the section */
.pp-sec--findings > ol {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
}
.pp-sec--findings > ol > li {
  display: grid;
  grid-template-columns: 2.2em minmax(0, 1fr);
  gap: var(--5ac-space-sm);
  padding: 16px 0;
  margin: 0;
  border-bottom: 1px solid var(--5ac-color-separator);
  font-size: 1.0625rem;
  line-height: 1.5;
}
.pp-sec--findings > ol > li::before {
  content: counter(list-item);
  font-family: var(--5ac-font-mono);
  font-size: 0.8125rem;
  color: var(--5ac-color-link);
  padding-top: 4px;
}
.pp-sec--findings > ol > li p {
  margin: 0;
  font-size: inherit;
  line-height: inherit;
}
.pp-sec--findings > ol > li b {
  font-weight: 600;
}

/* caveat + relevance blocks */
.pp-blk {
  border: 1px solid var(--5ac-color-separator);
  border-radius: var(--5ac-radius-md);
  padding: 20px 24px;
  margin-top: 24px;
  background: var(--5ac-color-background-secondary);
}
.pp-article > section.pp-blk > h2 {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0;
  margin: 0 0 8px;
}
.pp-article > section.pp-blk > p {
  margin: 0;
  font-size: 1rem;
  line-height: 1.55;
  color: var(--5ac-color-label);
}
.pp-blk--caveat {
  border-left: 3px solid var(--5ac-color-accent);
  background: var(--5ac-color-background-muted);
}
.pp-blk--apply {
  background: var(--5ac-color-highlight);
  border-color: var(--papers-apply-border);
  color: var(--papers-on-highlight);
}
/* base.css pins h2 { color: var(--ink) } — in dark mode that is light ink, so
   the gold block's heading must be re-pinned to the highlight ink explicitly
   (axe color-contrast, dark only: #e8e6dc on #F5E8C7 ≈ 1.1:1). */
.pp-article > section.pp-blk--apply > h2,
.pp-article > section.pp-blk--apply > p {
  color: var(--papers-on-highlight);
}

/* source line — the authored "Tên — URL" bullet becomes the reference's
   underlined source link; padding + negative margin buys the 44px hit area
   without changing the line's footprint (base.css `a:hover` underlines it). */
.pp-sec--source ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.pp-sec--source li {
  margin: 0;
  padding: 0;
  font-size: 1rem;
  line-height: 1.55;
}
.pp-sec--source a {
  display: inline-block;
  padding: 12px 0;
  margin: -12px 0;
  min-height: var(--5ac-accessibility-min-touch-target);
  min-width: var(--5ac-accessibility-min-touch-target);
  color: var(--5ac-color-link);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}
@media (hover: hover) and (pointer: fine) {
  .pp-sec--source a:hover {
    color: var(--5ac-color-accent-hover);
  }
}

/* sidenotes column */
.pp-sidenotes {
  padding-top: 128px;
}
.pp-sn {
  font-size: 0.8125rem;
  line-height: 1.5;
  color: var(--5ac-color-label-secondary);
  border-left: 2px solid var(--5ac-color-separator);
  padding-left: 12px;
  margin-bottom: 24px;
}
.pp-sn b {
  color: var(--5ac-color-label);
  font-weight: 600;
  display: block;
  margin-bottom: 4px;
  font-size: 0.78125rem;
}
.pp-sn a {
  display: inline-flex;
  align-items: center;
  min-height: var(--5ac-accessibility-min-touch-target);
  min-width: var(--5ac-accessibility-min-touch-target);
  color: var(--5ac-color-link);
  text-decoration: underline;
  text-underline-offset: 2px;
}
@media (hover: hover) and (pointer: fine) {
  .pp-sn a:hover {
    color: var(--5ac-color-accent-hover);
  }
}

/* ─── ≤1023px: reading grid collapses (TOC on top, sidenote below) ── */
@media (max-width: 1023px) {
  .pp-read {
    grid-template-columns: minmax(0, 1fr);
    max-width: var(--5ac-layout-container-max);
    gap: 0;
  }
  .pp-toc {
    position: static;
    border-bottom: 1px solid var(--5ac-color-separator);
    padding-bottom: 16px;
    margin-bottom: 8px;
  }
  .pp-sidenotes {
    padding-top: 0;
  }
  .pp-sn {
    border-left: 0;
    border-top: 1px solid var(--5ac-color-separator);
    padding: 12px 0 0;
    margin-top: 16px;
    margin-bottom: 16px;
  }
}

/* ─── ≤767px: mobile decision list (C2) ────────────────── */
@media (max-width: 767px) {
  .pp-hero {
    padding: 32px 0 8px;
  }
  .pp-lede {
    font-size: 1.0625rem;
  }
  .pp-sec-head {
    margin: 32px 0 12px;
  }
  .pp-sec-head h2 {
    font-size: 1.25rem;
  }
  .pp-sec-head .sub {
    margin-left: 0;
    flex-basis: 100%;
  }
  .pp-coll-idx {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
  }
  .pp-ce {
    padding: 16px 0;
  }
  .pp-combo {
    width: 100%;
  }
  .pp-tb-meta {
    display: none;
  }
  .pp-sec2 {
    flex-wrap: wrap;
  }
  .pp-sec2 .go {
    flex-basis: 100%;
    margin-left: 0;
    justify-content: flex-start;
  }
  .pp-sec--findings > ol > li {
    grid-template-columns: 1.8em minmax(0, 1fr);
    gap: 10px;
  }
  .pp-blk {
    padding: 16px;
  }
  .pp-pmeta {
    font-size: 0.875rem;
  }
  .pp-dek {
    font-size: 1.0625rem;
  }
}

/* ─── motion ───────────────────────────────────────────── */
@media (prefers-reduced-motion: reduce) {
  .pp-pop,
  .pp-row2,
  .pp-ce {
    transition: none !important;
  }
}

/* ─── filter state ([hidden] must win over the display rules above) ── */
.pp-pop[hidden],
.pp-row2[hidden],
.pp-empty[hidden],
.pp-it[hidden],
[role='group'][hidden] {
  display: none;
}