:root {
  --pp-paper: #f6f3ec;
  --pp-paper-raised: #fffdf8;
  --pp-ink-90: #201d16;
  --pp-ink-70: #4d4738;
  --pp-ink-50: #8b8471;
  --pp-rule: #d9d2bf;
  --pp-rule-strong: #c2b99f;
  --pp-accent: #7a2e22;
  --pp-accent-soft: #a8543f;

  --pp-serif: "Source Serif 4", "PT Serif", Georgia, "Times New Roman", serif;
  --pp-sans: "Inter", "Helvetica Neue", Arial, sans-serif;
  --pp-mono: "IBM Plex Mono", "JetBrains Mono", "SFMono-Regular", monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--pp-paper);
  color: var(--pp-ink-90);
  font-family: var(--pp-serif);
  min-height: 100%;
}
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}
.pp-section, .pp-masthead { scroll-margin-top: 1.25rem; }

/* ---------- READING PROGRESS ---------- */

.pp-progress {
  position: fixed;
  top: 0; left: 0;
  width: 100%;
  height: 3px;
  z-index: 30;
  background: transparent;
}
.pp-progress-bar {
  height: 100%;
  width: 0%;
  background: var(--pp-accent);
}

a { color: inherit; }

/* ---------- HOME BUTTON ---------- */

.pp-home-btn {
  position: fixed;
  top: 1.1rem;
  left: 1.1rem;
  z-index: 20;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--pp-sans);
  font-size: 0.78rem;
  color: #fff;
  text-decoration: none;
  background: rgba(20, 18, 14, 0.72);
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 50px;
  padding: 0.45rem 0.95rem 0.45rem 0.65rem;
  backdrop-filter: blur(6px);
  transition: background 0.15s ease, border-color 0.15s ease;
}
.pp-home-btn svg { width: 15px; height: 15px; }
.pp-home-btn:hover { background: rgba(20, 18, 14, 0.9); border-color: rgba(255, 255, 255, 0.6); }

/* ---------- MASTHEAD (no hero image on this page; starts at top) ---------- */

.pp-masthead {
  width: 80vw;
  max-width: 78rem;
  margin: 0 auto;
  padding: 4.5rem 1.75rem 0;
  text-align: left;
}
.pp-doctype {
  display: inline-block;
  font-family: var(--pp-sans);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--pp-accent);
  border: 1px solid var(--pp-rule-strong);
  border-radius: 3px;
  padding: 0.3rem 0.7rem;
  margin-bottom: 1.2rem;
}
.pp-masthead h1 {
  font-family: var(--pp-serif);
  font-weight: 600;
  font-size: clamp(1.9rem, 5.6vw, 3rem);
  line-height: 1.14;
  letter-spacing: -0.01em;
  margin: 0 0 0.9rem;
  color: var(--pp-ink-90);
}
.pp-masthead h1 em {
  display: block;
  color: var(--pp-ink-70);
  font-style: italic;
  font-weight: 500;
  font-size: 0.62em;
  margin-top: 0.35rem;
}
.pp-hero-sub {
  font-family: var(--pp-serif);
  font-size: 1.08rem;
  line-height: 1.6;
  color: var(--pp-ink-70);
  max-width: 38rem;
  margin: 0 0 1.5rem;
}
.pp-hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 1.1rem 1.5rem;
  font-family: var(--pp-mono);
  font-size: 0.72rem;
  letter-spacing: 0.01em;
  color: var(--pp-ink-50);
  border-top: 1px solid var(--pp-rule);
  border-bottom: 1px solid var(--pp-rule);
  padding: 0.9rem 0;
  margin-bottom: 0.5rem;
}

/* ---------- TABLE OF CONTENTS / SECTION NAV ---------- */

.pp-toc-wrap {
  width: 80vw;
  max-width: 78rem;
  margin: 0 auto;
  padding: 1.5rem 1.75rem 0;
}
.pp-toc {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 0;
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--pp-sans);
}
.pp-toc li { width: 50%; }
.pp-toc a {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--pp-ink-70);
  font-size: 0.86rem;
  padding: 0.3rem 0.6rem 0.3rem 0;
  border-left: 2px solid transparent;
  padding-left: 0.6rem;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.pp-toc a:hover { color: var(--pp-accent); }
.pp-toc a.pp-toc-active { color: var(--pp-accent); border-left-color: var(--pp-accent); font-weight: 600; }
.pp-toc-num { font-family: var(--pp-mono); color: var(--pp-ink-50); font-size: 0.8rem; flex: none; }
@media (max-width: 30rem) {
  .pp-toc li { width: 100%; }
}

/* ---------- PAPER BODY ---------- */

.pp-paper {
  width: 80vw;
  max-width: 78rem;
  margin: 0 auto;
  padding: 3.5rem 1.75rem 2rem;
}

.pp-section { margin-bottom: 3.75rem; }

.pp-section h2 {
  display: flex;
  align-items: baseline;
  gap: 0.65rem;
  font-family: var(--pp-serif);
  font-weight: 600;
  font-size: 1.55rem;
  letter-spacing: -0.005em;
  color: var(--pp-ink-90);
  margin: 0 0 0.4rem;
  padding-bottom: 0.6rem;
  border-bottom: 1.5px solid var(--pp-ink-90);
}
.pp-num {
  font-family: var(--pp-mono);
  font-size: 0.95rem;
  color: var(--pp-accent);
  font-weight: 600;
}

.pp-lede {
  color: var(--pp-ink-70);
  font-size: 1.02rem;
  line-height: 1.7;
  margin: 1.1rem 0 1.75rem;
}

.pp-section p { line-height: 1.7; color: var(--pp-ink-70); }

.pp-authors {
  font-family: var(--pp-sans);
  font-size: 0.86rem;
  color: var(--pp-ink-50);
  margin: 0.9rem 0 0;
}
.pp-authors strong { color: var(--pp-accent); font-weight: 700; }

.pp-abstract {
  font-size: 1.01rem;
  line-height: 1.75;
  color: var(--pp-ink-70);
  margin: 1.1rem 0 0;
  padding-left: 1.1rem;
  border-left: 2px solid var(--pp-rule-strong);
}

/* ---------- STAKEHOLDER-STYLE GRID (reused for SE Parallel section) ---------- */

.pp-stake-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0;
  border-top: 1px solid var(--pp-rule);
  margin-top: 0.5rem;
}
.pp-stake-col {
  padding: 1.1rem 1.5rem 1.1rem 0;
  border-bottom: 1px solid var(--pp-rule);
}
.pp-stake-col:nth-child(odd) {
  border-right: 1px solid var(--pp-rule);
  padding-right: 1.5rem;
}
.pp-stake-col:nth-child(even) { padding-left: 1.5rem; }
@media (max-width: 34rem) {
  .pp-stake-grid { grid-template-columns: 1fr; }
  .pp-stake-col:nth-child(odd) { border-right: none; padding-right: 0; }
  .pp-stake-col:nth-child(even) { padding-left: 0; }
}
.pp-stake-head {
  font-family: var(--pp-sans);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 700;
  color: var(--pp-accent);
  margin: 0 0 0.4rem;
}
.pp-stake-desc {
  margin: 0;
  font-size: 0.93rem;
  line-height: 1.55;
  color: var(--pp-ink-70);
}

/* ---------- DOCUMENT VIEWER (full document, scrolls within a fixed-height box) ---------- */

.pp-book-wrap {
  margin-top: 0.5rem;
  background: #3a352b;
  border-radius: 8px;
  padding: 1rem;
  box-shadow: 0 1px 0 rgba(32, 29, 22, 0.05), 0 12px 32px -18px rgba(32, 29, 22, 0.55);
}
.pp-book {
  height: 78vh;
  max-height: 46rem;
  min-height: 24rem;
  overflow-y: auto;
  overflow-x: hidden;
  border-radius: 4px;
  scrollbar-color: rgba(247, 244, 236, 0.35) transparent;
}
.pp-book-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0 0.15rem 0.75rem;
  font-family: var(--pp-sans);
  font-size: 0.72rem;
  color: rgba(247, 244, 236, 0.55);
}
.pp-book-toolbar span strong { color: rgba(247, 244, 236, 0.85); }
.pp-book-toolbar-right {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}
.pp-book-expand-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--pp-sans);
  font-size: 0.72rem;
  font-weight: 600;
  color: rgba(247, 244, 236, 0.85);
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 5px;
  padding: 0.35rem 0.65rem;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease;
}
.pp-book-expand-btn svg { width: 13px; height: 13px; }
.pp-book-expand-btn:hover { background: rgba(255, 255, 255, 0.16); border-color: rgba(255, 255, 255, 0.4); }
.pp-book-expand-btn:focus-visible { outline: 2px solid #d8cba8; outline-offset: 1px; }

/* ---------- DOCUMENT VIEWER: expanded / "fullscreen" state ---------- */

.pp-book-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 90;
  background: rgba(12, 10, 8, 0.82);
}
.pp-book-backdrop.pp-book-backdrop-open { display: block; }

.pp-book-wrap.pp-book-expanded {
  position: fixed;
  z-index: 91;
  top: 2.5vh;
  left: 50%;
  transform: translateX(-50%);
  width: min(97vw, 84rem);
  max-width: none;
  margin: 0;
  box-shadow: 0 30px 70px -20px rgba(0, 0, 0, 0.7);
}
.pp-book-wrap.pp-book-expanded .pp-book {
  height: 95vh;
  max-height: none;
}
/* Expanded mode: single-page vertical scroll instead of two-page spread,
   so each page renders much larger. Spine hidden, spreads stack columns. */
.pp-book-wrap.pp-book-expanded .pp-book-spread {
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}
.pp-book-wrap.pp-book-expanded .pp-book-spine { display: none; }
.pp-book-wrap.pp-book-expanded .pp-book-col {
  max-width: none;
  width: 100%;
  align-items: center;
}
.pp-book-wrap.pp-book-expanded .pp-book-page {
  width: auto;
  height: 90vh;
  max-width: 96%;
}
.pp-book-wrap.pp-book-expanded .pp-book-page img {
  width: auto;
  height: 100%;
  max-width: 100%;
  object-fit: contain;
}
body.pp-book-lock { overflow: hidden; }
.pp-book-expand-btn .pp-book-expand-label-collapse { display: none; }
.pp-book-wrap.pp-book-expanded .pp-book-expand-label-expand { display: none; }
.pp-book-wrap.pp-book-expanded .pp-book-expand-label-collapse { display: inline; }
@media (max-width: 40rem) {
  .pp-book-wrap.pp-book-expanded {
    top: 0; left: 0; transform: none;
    width: 100vw; height: 100vh;
    border-radius: 0;
  }
  .pp-book-wrap.pp-book-expanded .pp-book { height: calc(100vh - 3rem); }
  .pp-book-wrap.pp-book-expanded .pp-book-page { height: 82vh; max-width: 96%; }
}
.pp-book-loading {
  font-family: var(--pp-sans);
  font-size: 0.85rem;
  color: rgba(247, 244, 236, 0.6);
  text-align: center;
  padding: 3rem 0;
}
.pp-book-spread {
  display: flex;
  justify-content: center;
  gap: 4px;
  margin-bottom: 4px;
}
.pp-book-spread:last-child { margin-bottom: 0; }
.pp-book-col {
  flex: 1 1 0;
  max-width: 21rem;
  display: flex;
  flex-direction: column;
}
.pp-book-page {
  width: 100%;
  background: #fff;
  box-shadow: 0 2px 10px -2px rgba(0, 0, 0, 0.4);
  min-height: 4rem;
  display: flex;
  align-items: center;
  justify-content: center;
}
.pp-book-page img {
  display: block;
  width: 100%;
  height: auto;
}
.pp-book-page.pp-book-blank {
  background: transparent;
  box-shadow: none;
}
.pp-book-pagenum {
  font-family: var(--pp-mono);
  font-size: 0.62rem;
  color: rgba(247, 244, 236, 0.4);
  text-align: center;
  margin-top: 0.15rem;
}
.pp-book-spine {
  width: 2px;
  background: rgba(0, 0, 0, 0.15);
  align-self: stretch;
}
@media (max-width: 40rem) {
  .pp-book-wrap { padding: 0.65rem; }
  .pp-book { height: 70vh; }
  .pp-book-spread { flex-direction: column; align-items: center; }
  .pp-book-col { max-width: 100%; }
  .pp-book-spine { display: none; }
}

/* ---------- DOWNLOAD BUTTON ---------- */

.pp-download-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--pp-sans);
  font-size: 0.92rem;
  font-weight: 600;
  color: #f6f3ec;
  text-decoration: none;
  background: var(--pp-accent);
  border-radius: 6px;
  padding: 0.85rem 1.4rem;
  margin-top: 0.75rem;
  transition: background 0.15s ease;
}
.pp-download-btn:hover { background: var(--pp-accent-soft); }
.pp-download-btn svg { width: 18px; height: 18px; }

/* ---------- MOBILE TUNING ---------- */

@media (max-width: 40rem) {
  .pp-masthead { padding: 3rem 1.25rem 0; }
  .pp-toc-wrap { padding: 1.25rem 1.25rem 0; }
  .pp-paper { padding: 2.25rem 1.25rem 1.5rem; }
  .pp-footer { padding: 0 1.25rem 3rem; }
  .pp-section h2 { font-size: 1.3rem; }
}

/* ---------- FOOTER ---------- */

.pp-footer {
  max-width: 46rem;
  margin: 0 auto;
  padding: 0 1.75rem 4rem;
  border-top: 1px solid var(--pp-rule);
  padding-top: 1.75rem;
  font-family: var(--pp-sans);
  font-size: 0.78rem;
  color: var(--pp-ink-50);
  line-height: 1.65;
}
.pp-footer a { color: var(--pp-accent-soft); text-decoration: none; }
.pp-footer a:hover { text-decoration: underline; }
.pp-footer p { margin: 0 0 0.6rem; }