/* Tree-of-Life "Read" feature — scrollytelling reading mode.
   Modelled on the family-tree scroll pages (john-family-tree-scroll.css):
   a scrolling prose column on the LEFT, a sticky visual on the RIGHT that
   changes as each section scrolls into view. Here it runs inside a full-screen
   overlay launched from the node "Read" tab, so it never fights the SPA's own
   sticky/overflow layout. Layers on top of the john-clean design tokens.
   No-JS / reduced-motion: the active scene is simply shown, statically. */

:root {
  --etr-accent: #b5894e;          /* bronze — switch "lit", spurs, highlights */
  --etr-accent-2: #3f5a4c;        /* deep serpent green */
  --etr-sepia: #8a6d3b;           /* fossil/record sepia */
  --etr-dark: #2b2b2b;            /* switch "gone dark" */
}

/* ─────────────────────────── the Read tab "cover" ─────────────────────── */
.etr-cover {
  max-width: 60ch;
  padding: 0.5rem 0 1.5rem;
}
.etr-cover__eyebrow {
  font-family: var(--jh-font-display, serif);
  letter-spacing: 0.2em; text-transform: uppercase;
  font-size: 0.72rem; color: var(--etr-accent); margin: 0 0 0.6rem;
}
.etr-cover__title {
  font-family: var(--jh-font-display, serif);
  font-size: clamp(1.9rem, 4vw, 3rem); line-height: 1.05; margin: 0;
}
.etr-cover__sub {
  font-family: var(--jh-font-display, serif);
  font-size: 0.9rem; color: var(--jh-muted); letter-spacing: 0.04em; margin: 0.5rem 0 0;
}
.etr-cover__teaser {
  font-size: 1.1rem; font-style: italic; color: var(--etr-accent-2);
  line-height: 1.6; margin: 1.1rem 0 1.4rem; max-width: 48ch;
}
.etr-contents {
  list-style: none; margin: 0 0 1.6rem; padding: 1rem 1.2rem;
  border: 1px solid var(--jh-line); border-left: 3px solid var(--etr-accent);
  border-radius: 6px; background: var(--jh-panel, #faf7f1);
  counter-reset: etr-step;
}
.etr-contents li {
  counter-increment: etr-step; padding: 0.28rem 0; font-size: 0.95rem;
  display: flex; gap: 0.7rem; align-items: baseline; color: var(--jh-text);
}
.etr-contents li::before {
  content: counter(etr-step); font-family: var(--jh-font-display, serif);
  color: var(--etr-accent); font-size: 0.8rem; min-width: 1.3em;
}
.etr-begin {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-family: var(--jh-font-display, serif); letter-spacing: 0.04em;
  font-size: 1rem; cursor: pointer;
  padding: 0.7rem 1.4rem; border-radius: 999px; border: 1px solid var(--etr-accent);
  background: var(--etr-accent); color: #fff; transition: filter 0.2s, transform 0.2s;
}
.etr-begin:hover { filter: brightness(1.06); transform: translateY(-1px); }
.etr-cover__hint { font-size: 0.82rem; color: var(--jh-muted); margin: 0.8rem 0 0; }

/* ─────────────────────────── the reading-mode overlay ─────────────────── */
.etr-overlay {
  position: fixed; inset: 0; z-index: 6000;
  background: var(--jh-bg, #fdfbf6);
  display: flex; flex-direction: column;
  --etr-row: 100vh;
}
.etr-bar {
  flex: 0 0 auto; display: flex; align-items: center; gap: 1rem;
  padding: 0.6rem clamp(0.8rem, 3vw, 2rem);
  border-bottom: 1px solid var(--jh-line); background: var(--jh-bg, #fdfbf6);
  position: relative; z-index: 2;
}
.etr-bar__title {
  font-family: var(--jh-font-display, serif); font-size: 0.95rem;
  color: var(--jh-text); margin: 0; flex: 1 1 auto;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.etr-bar__title b { color: var(--etr-accent); font-weight: 600; }
.etr-close {
  flex: 0 0 auto; cursor: pointer; border: 1px solid var(--jh-line);
  background: transparent; color: var(--jh-muted); border-radius: 999px;
  font-size: 0.8rem; letter-spacing: 0.06em; text-transform: uppercase;
  padding: 0.4rem 0.9rem; font-family: var(--jh-font-display, serif);
  transition: color 0.2s, border-color 0.2s;
}
.etr-close:hover { color: var(--etr-accent); border-color: var(--etr-accent); }
.etr-progress { position: absolute; left: 0; right: 0; bottom: -1px; height: 2px; background: transparent; }
.etr-progress__fill { height: 100%; width: 0; background: var(--etr-accent); transition: width 0.1s linear; }

.etr-scroll { flex: 1 1 auto; overflow-y: auto; overflow-x: hidden; scroll-behavior: smooth; }
.etr-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
  gap: clamp(1.5rem, 4vw, 4rem);
  width: min(1180px, calc(100% - clamp(2rem, 6vw, 6rem)));
  margin: 0 auto;
}

/* left: scrolling prose */
.etr-steps { padding-bottom: 12vh; }
.etr-lede { min-height: 40vh; display: flex; flex-direction: column; justify-content: flex-end; padding: 8vh 0 2vh; }
.etr-lede__eyebrow {
  font-family: var(--jh-font-display, serif); letter-spacing: 0.2em; text-transform: uppercase;
  font-size: 0.72rem; color: var(--etr-accent); margin: 0 0 0.5rem;
}
.etr-lede__title { font-family: var(--jh-font-display, serif); font-size: clamp(2rem, 4.5vw, 3.4rem); line-height: 1.04; margin: 0; }
.etr-lede__byline { color: var(--jh-muted); font-style: italic; margin: 0.7rem 0 0; }

.etr-step {
  min-height: 88vh; display: flex; flex-direction: column; justify-content: center;
  padding: 6vh 0; opacity: 0.32; transition: opacity 0.5s ease;
}
.etr-step.is-active { opacity: 1; }
.etr-step__heading {
  font-family: var(--jh-font-display, serif); font-size: clamp(1.4rem, 2.8vw, 2.1rem);
  line-height: 1.14; margin: 0 0 1rem; color: var(--jh-text);
}
.etr-step__num {
  display: block; font-size: 0.72rem; letter-spacing: 0.18em; text-transform: uppercase;
  color: var(--etr-accent); margin-bottom: 0.5rem; font-weight: 400;
}
.etr-step__body { font-size: 1.08rem; line-height: 1.75; color: var(--jh-text); max-width: 46ch; }
.etr-step__body p { margin: 0 0 1.05rem; }
.etr-step__body em { font-style: italic; }
.etr-step__body strong { font-weight: 600; }
.etr-step__caption { display: none; }   /* shown only on mobile, under the stage band */

/* end matter — inference ledger + references */
.etr-endmatter { min-height: 60vh; padding: 6vh 0 16vh; max-width: 52ch; }
.etr-endmatter h3 {
  font-family: var(--jh-font-display, serif); font-size: 1.3rem; margin: 0 0 0.4rem;
}
.etr-endmatter__intro { color: var(--jh-muted); font-style: italic; font-size: 0.92rem; margin: 0 0 1.2rem; }
.etr-infer { list-style: none; margin: 0 0 2.2rem; padding: 0; display: grid; gap: 0.9rem; }
.etr-infer__item {
  padding: 0.9rem 1.1rem; border: 1px solid var(--jh-line); border-radius: 6px;
  background: var(--jh-panel, #faf7f1); font-size: 0.96rem; line-height: 1.6;
}
.etr-tier {
  display: inline-block; font-family: var(--jh-font-display, serif);
  font-size: 0.64rem; letter-spacing: 0.12em; text-transform: uppercase;
  padding: 0.16rem 0.55rem; border-radius: 999px; margin: 0 0 0.5rem;
  border: 1px solid currentColor;
}
.etr-tier--demonstrated { color: var(--etr-accent-2); }
.etr-tier--strongly-inferred { color: var(--etr-sepia); }
.etr-tier--plausible-reconstruction { color: var(--jh-muted); }
.etr-refs { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.6rem; }
.etr-refs li { font-size: 0.86rem; color: var(--jh-muted); line-height: 1.5; padding-left: 1rem; text-indent: -1rem; }
.etr-refs em { font-style: italic; }

/* right: sticky stage with the scenes */
.etr-stage { position: sticky; top: 0; align-self: start; height: 100vh; display: flex; flex-direction: column; justify-content: center; }
.etr-scenes {
  position: relative; width: 100%; flex: 1 1 auto;
  min-height: 0; display: flex; align-items: center; justify-content: center;
}
.etr-scene {
  position: absolute; inset: 0; opacity: 0; transition: opacity 0.7s ease;
  display: flex; align-items: center; justify-content: center; pointer-events: none;
}
.etr-scene.is-active { opacity: 1; }
.etr-scene svg { width: 100%; height: 100%; max-height: 78vh; overflow: visible; }
.etr-caption {
  flex: 0 0 auto; text-align: center; color: var(--jh-muted);
  font-size: 0.92rem; line-height: 1.55; max-width: 42ch; margin: 0.6rem auto 0;
  min-height: 4.5em; transition: opacity 0.4s ease;
}
.etr-caption b { color: var(--etr-accent-2); font-weight: 600; }

/* shared svg primitives */
.etr-scene text { font-family: var(--jh-font-display, serif); fill: var(--jh-text); }
.etr-lbl { font-size: 17px; fill: var(--jh-muted); letter-spacing: 0.04em; }
.etr-lbl--accent { fill: var(--etr-accent); }
.etr-snake { fill: none; stroke: var(--etr-accent-2); stroke-linecap: round; stroke-linejoin: round; }

/* ── mobile: stack; stage becomes a sticky band on top (like the family tree) ── */
@media (max-width: 860px) {
  .etr-grid { grid-template-columns: 1fr; gap: 0; }
  .etr-stage {
    grid-row: 1; height: 42vh; background: var(--jh-bg, #fdfbf6);
    border-bottom: 1px solid var(--jh-line); z-index: 2; padding-bottom: 0.4rem;
  }
  .etr-scene svg { max-height: 30vh; }
  .etr-caption { display: none; }
  .etr-steps { grid-row: 2; }
  .etr-lede { min-height: auto; padding: 4vh 0 2vh; }
  .etr-step { min-height: 72vh; padding: 5vh 0; }
  .etr-step__body { max-width: none; }
  .etr-step__caption {
    display: block; font-size: 0.88rem; color: var(--jh-muted); font-style: italic;
    border-left: 3px solid var(--etr-accent); padding: 0.3rem 0 0.3rem 0.8rem; margin: 0 0 1rem;
  }
}

/* ════════════════════════════ scene animations ════════════════════════════
   Each scene's motion is gated on `.etr-scene.is-active` so it (re)plays when
   the matching section scrolls into view, and resets when it leaves. */

/* 1 · python-spurs — the living receipt */
.etr-spur-glow { transform-origin: center; opacity: 0.0; }
.etr-scene.is-active .etr-spur-glow { animation: etr-pulse 3.2s ease-in-out infinite; }
.etr-scene.is-active .etr-spur { animation: etr-twinkle 3.2s ease-in-out infinite; }
@keyframes etr-pulse { 0%,100% { opacity: 0.0; transform: scale(0.7); } 50% { opacity: 0.55; transform: scale(1.15); } }
@keyframes etr-twinkle { 0%,100% { fill: var(--etr-accent); } 50% { fill: #e7c489; } }

/* 2 · najash — the fossil draws itself in */
.etr-fossil-leg { stroke-dasharray: 260; stroke-dashoffset: 260; }
.etr-scene.is-active .etr-fossil-leg { animation: etr-draw 1.6s ease forwards; }
.etr-fossil-vert { opacity: 0; }
.etr-scene.is-active .etr-fossil-vert { animation: etr-fade-in 0.05s linear forwards; }
.etr-scene.is-active .etr-fv1 { animation-delay: 0.1s; } .etr-scene.is-active .etr-fv2 { animation-delay: 0.25s; }
.etr-scene.is-active .etr-fv3 { animation-delay: 0.4s; } .etr-scene.is-active .etr-fv4 { animation-delay: 0.55s; }
.etr-scene.is-active .etr-fv5 { animation-delay: 0.7s; } .etr-scene.is-active .etr-fv6 { animation-delay: 0.85s; }
@keyframes etr-draw { to { stroke-dashoffset: 0; } }
@keyframes etr-fade-in { to { opacity: 1; } }

/* 3 · elongation — vertebrae multiply, regions blur into one thorax */
.etr-vert { opacity: 0; transform-box: fill-box; transform-origin: center; }
.etr-scene.is-active .etr-vert { animation: etr-rise 2.6s ease forwards; }
.etr-region { opacity: 1; }
.etr-scene.is-active .etr-region--side { animation: etr-merge 2.8s ease forwards; }
.etr-clock-hand { transform-box: fill-box; transform-origin: bottom center; }
.etr-scene.is-active .etr-clock-hand { animation: etr-tick 1.1s steps(8) infinite; }
.etr-count-hi { opacity: 0; }
.etr-scene.is-active .etr-count-hi { animation: etr-fade-in 0.6s ease 1.6s forwards; }
@keyframes etr-rise { to { opacity: 1; } }
@keyframes etr-merge { to { opacity: 0; } }
@keyframes etr-tick { to { transform: rotate(360deg); } }

/* 4 · switch — bud begins, ZRS goes dark, the bud withers; a faint rescue glow */
.etr-bud { transform-box: fill-box; transform-origin: 30% 50%; }
.etr-scene.is-active .etr-bud { animation: etr-bud 6.5s ease-in-out infinite; }
.etr-signal { opacity: 0; }
.etr-scene.is-active .etr-signal { animation: etr-signal 6.5s ease-in-out infinite; }
.etr-zrs-box { fill: var(--etr-dark); transition: fill 0.4s; }
.etr-scene.is-active .etr-zrs-box { animation: etr-zrs 6.5s ease-in-out infinite; }
.etr-zrs-glow { opacity: 0; }
.etr-scene.is-active .etr-zrs-glow { animation: etr-zrs-glow 6.5s ease-in-out infinite; }
@keyframes etr-bud {
  0% { transform: scale(0.6); } 18% { transform: scale(1.0); }
  34% { transform: scale(0.92); } 60%,100% { transform: scale(0.34); }
}
@keyframes etr-signal { 0%,8% { opacity: 0; } 18% { opacity: 0.85; } 40% { opacity: 0.1; } 100% { opacity: 0; } }
@keyframes etr-zrs {
  0%,8% { fill: var(--etr-accent); } 30% { fill: var(--etr-dark); }
  82% { fill: var(--etr-dark); } 90% { fill: var(--etr-accent); } 100% { fill: var(--etr-dark); }
}
@keyframes etr-zrs-glow { 0%,82% { opacity: 0; } 90% { opacity: 0.6; } 100% { opacity: 0; } }

/* 5 · ghost-leg — switched off, not deleted */
.etr-ghost { opacity: 0.0; }
.etr-scene.is-active .etr-ghost { animation: etr-ghost 4.5s ease-in-out infinite; }
.etr-toggle-knob { transform-box: fill-box; transform-origin: center; }
.etr-scene.is-active .etr-toggle-knob { animation: etr-nudge 4.5s ease-in-out infinite; }
@keyframes etr-ghost { 0%,100% { opacity: 0.12; } 50% { opacity: 0.4; } }
@keyframes etr-nudge { 0%,70%,100% { transform: translateX(0); } 80% { transform: translateX(34px); } 88% { transform: translateX(6px); } }

@media (prefers-reduced-motion: reduce) {
  .etr-scene, .etr-step, .etr-caption, .etr-progress__fill { transition: none !important; }
  .etr-scene * { animation: none !important; }
  .etr-fossil-leg { stroke-dashoffset: 0 !important; }
  .etr-fossil-vert, .etr-vert, .etr-count-hi { opacity: 1 !important; }
  .etr-region--side { opacity: 0.5 !important; }
  .etr-bud { transform: scale(0.4) !important; }
  .etr-zrs-box { fill: var(--etr-dark) !important; }
  .etr-ghost { opacity: 0.3 !important; }
  .etr-scroll { scroll-behavior: auto; }
}