:root {
  --paper: #f4efe2;
  --paper-card: #faf6ec;
  --ink: #1b1916;
  --ink-soft: #4c4842;
  --ink-faint: #948c7e;
  --line: #d8cdb3;
  --line-soft: #e3dac4;
  --accent: #bb3b21;
  --max: 1080px;
}

html { scroll-behavior: smooth; color-scheme: light; }

html[data-theme="dark"] {
  color-scheme: dark;
  --paper: #1a1816;
  --paper-card: #221f1c;
  --ink: #ede8dc;
  --ink-soft: #b5aea2;
  --ink-faint: #7a746a;
  --line: #3a3530;
  --line-soft: #2c2824;
  --accent: #d4533a;
}

/* keyboard focus — visible for tab/keyboard users, not on mouse click */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}
.panel:focus-visible { outline-offset: 8px; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .panel { animation: none; }
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: "EB Garamond", Georgia, serif;
  color: var(--ink);
  background-color: var(--paper);
  /* clean, faint square grid — graph-paper calm */
  background-image:
    linear-gradient(var(--line-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--line-soft) 1px, transparent 1px);
  background-size: 30px 30px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.page {
  max-width: var(--max);
  margin: 0 auto;
  padding: 2.6rem 1.8rem 2.5rem;
}

/* ───────────────────────── Masthead ───────────────────────── */
.masthead {
  border-bottom: 1.5px solid var(--ink);
  padding-bottom: 1.1rem;
}

.masthead-top {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 1rem;
}

.theme-toggle {
  font-family: inherit;
  font-size: 0.74rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-faint);
  background: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.35rem 0.75rem;
  cursor: pointer;
  flex: 0 0 auto;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.theme-toggle:hover {
  color: var(--ink);
  border-color: var(--ink-soft);
}

.brand {
  display: flex;
  align-items: flex-end;
  gap: 0.7rem;
}

.brand-text { padding-bottom: 0.1rem; }

.mark {
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
}

.mark img {
  height: 50px;
  width: auto;
  display: block;
  transition: filter 0.2s ease, opacity 0.2s ease;
}

.brand-text h1 {
  font-weight: 600;
  font-size: clamp(1.9rem, 4.5vw, 2.7rem);
  letter-spacing: 0.01em;
  line-height: 1;
}

/* ───────────────────────── Tabs ───────────────────────── */
.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.2rem 1.5rem;
  margin-top: 1.3rem;
}

.tab {
  font-family: inherit;
  font-size: 1.05rem;
  color: var(--ink-faint);
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.2rem 0;
  position: relative;
  transition: color 0.2s ease;
  letter-spacing: 0.02em;
}

.tab::after {
  content: "";
  position: absolute;
  left: 0; right: 100%;
  bottom: -1px;
  height: 2px;
  background: var(--accent);
  transition: right 0.25s ease;
}

.tab:hover { color: var(--ink-soft); }
.tab.is-active { color: var(--ink); font-weight: 600; }
.tab.is-active::after { right: 0; }

/* ───────────────────────── Sheet / Panels ───────────────────────── */
.sheet { padding-top: 2rem; }

.panel { display: none; animation: rise 0.4s ease both; }
.panel.is-active { display: block; }

@keyframes rise {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.panel-head {
  margin-bottom: 1.9rem;
  padding-bottom: 0.9rem;
  border-bottom: 1px solid var(--line);
}

.folio {
  font-size: 0.78rem;
  letter-spacing: 0.32em;
  color: var(--accent);
  display: block;
  margin-bottom: 0.35rem;
}

.panel-head h2 {
  font-size: clamp(1.8rem, 4vw, 2.3rem);
  font-weight: 600;
  line-height: 1.05;
}

.lede {
  font-style: italic;
  color: var(--ink-soft);
  margin-top: 0.3rem;
  font-size: 1.06rem;
}

/* ───────────────────────── Intro ───────────────────────── */
.intro-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: start;
  gap: 0 2.4rem;
}

.intro-main {
  padding-right: 0;
}

.intro-hi {
  font-style: italic;
  color: var(--accent);
  font-size: 1.15rem;
  margin-bottom: 0.8rem;
}

.intro-lead {
  font-size: clamp(1.5rem, 3.2vw, 2.05rem);
  line-height: 1.4;
  color: var(--ink);
}

.intro-sub {
  margin-top: 1.3rem;
  font-size: 1.12rem;
  color: var(--ink-soft);
}

.intro-side {
  border-left: 1px solid var(--line);
  padding-left: 2.4rem;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  gap: 1.4rem;
}

.side-block h4 {
  font-size: 0.74rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--ink-faint);
  font-weight: 600;
  margin-bottom: 0.55rem;
}

.side-block p { font-size: 1.05rem; color: var(--ink-soft); }
.dot { color: var(--accent); margin: 0 0.45rem; }

.side-links { font-size: 1.05rem; color: var(--ink-soft); }
.side-links + .side-links { margin-top: 0.35rem; }

.side-links a,
.side-links button,
.inline-link {
  font-family: inherit;
  font-size: 1.05rem;
  color: var(--ink);
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  text-decoration: none;
  position: relative;
  transition: color 0.18s ease;
}

.side-links a::after,
.side-links button::after,
.inline-link::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.22s ease;
}

.side-links a:hover,
.side-links button:hover,
.inline-link:hover { color: var(--accent); }
.side-links a:hover::after,
.side-links button:hover::after,
.inline-link:hover::after { transform: scaleX(1); }

.inline-link {
  font-style: italic;
  color: var(--accent);
}
.inline-link::after { bottom: 0; transform: scaleX(1); opacity: 0.4; }
.inline-link:hover::after { opacity: 1; }

/* ───────────────────────── Cards ───────────────────────── */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 1.1rem;
}

.card {
  border: 1px solid var(--ink);
  padding: 1.3rem 1.4rem 1.5rem;
  background: var(--paper-card);
  transition: transform 0.2s ease, box-shadow 0.2s ease, background-color 0.2s ease;
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: 5px 6px 0 var(--ink);
}

.card h3 { font-size: 1.4rem; font-weight: 600; margin-bottom: 0.45rem; }
.card p { color: var(--ink-soft); font-size: 1.03rem; }
.card-link {
  color: var(--ink);
  text-decoration: none;
  position: relative;
  transition: color 0.18s ease;
}
.card-link::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.22s ease;
}
.card-link:hover { color: var(--accent); }
.card-link:hover::after { transform: scaleX(1); }
.card .trek-label,
.card .book-label { font-weight: 600; color: var(--ink); }

/* shared list markers — vermilion arrow, paper-tone editorial */
.card-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.card-list li {
  position: relative;
  color: var(--ink-soft);
  font-size: 1.03rem;
  line-height: 1.6;
}

.card-list li + li { margin-top: 0.5rem; }

.card-list li::before {
  content: "→";
  position: absolute;
  font-family: "Spectral", "EB Garamond", Georgia, serif;
  font-size: 0.82rem;
  font-weight: 400;
  color: var(--accent);
  opacity: 0.72;
  line-height: 1.6;
}

.shelf-list li,
.trek-list li {
  padding-left: 1.15rem;
}

.shelf-list li::before,
.trek-list li::before {
  left: 0;
  top: 0.08em;
}

.card .trek-lead {
  margin-bottom: 0.65rem;
}

/* ───────────────────────── Subgroups (Motion) ───────────────────────── */
.subgroup { margin-bottom: 2rem; }
.subgroup:last-child { margin-bottom: 0; }

.subhead {
  font-size: 0.78rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--ink-faint);
  font-weight: 600;
  margin-bottom: 0.8rem;
}

/* clearly-marked content placeholders */
.todo {
  color: var(--accent);
  font-style: italic;
  opacity: 0.7;
  border-bottom: 1px dashed currentColor;
}

/* ───────────────────────── Colophon ───────────────────────── */
.colophon {
  margin-top: 2.5rem;
  padding-top: 1.1rem;
  border-top: 1.5px solid var(--ink);
  display: flex;
  align-items: center;
  gap: 0.8rem;
  color: var(--ink-faint);
  font-size: 0.9rem;
  font-style: italic;
}

.rule-dot { width: 7px; height: 7px; background: var(--accent); border-radius: 50%; flex: 0 0 auto; }
.colophon p { flex: 1; }

.footer-tiger { flex: 0 0 auto; display: inline-flex; }
.footer-tiger img {
  height: 40px;
  width: auto;
  display: block;
  opacity: 0.55;
  transition: filter 0.2s ease, opacity 0.2s ease;
}

/* dark assets are black-on-transparent — invert to warm paper-tone silhouettes */
html[data-theme="dark"] .mark img {
  filter: invert(0.92) sepia(0.15);
  opacity: 0.72;
}

html[data-theme="dark"] .footer-tiger img {
  filter: invert(0.92) sepia(0.15);
  opacity: 0.42;
}

/* ───────────────────────── Responsive ───────────────────────── */
@media (max-width: 720px) {
  .intro-grid { grid-template-columns: 1fr; }
  .intro-main { padding-right: 0; }
  .intro-side {
    border-left: none;
    border-top: 1px solid var(--line);
    padding-left: 0;
    padding-top: 1.6rem;
    margin-top: 1.6rem;
    justify-content: flex-start;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 1.6rem 2.4rem;
  }
}

@media (max-width: 540px) {
  .page { padding: 2.2rem 1.1rem 3rem; }
  .tabs { gap: 0.1rem 1.1rem; }
  .tab { font-size: 0.98rem; }
}