/* ==========================================================================
   The Hidden Architecture of Reading — opening exhibit
   Language is the exhibit. Everything else exists to reveal its structure.
   ========================================================================== */

:root {
  --paper:        #FAF6EF;   /* warm off-white */
  --ink:          #2E2B27;   /* dark charcoal */
  --ink-soft:     #6E675E;   /* captions, counters */
  --glow:         #C98A2E;   /* warm lamplight for stressed syllables */
  --glow-deep:    #8C5A12;   /* the same lamplight, deep enough to read by */
  --glow-halo:    rgba(214, 158, 74, 0.38);
  --boundary:     #A89C8C;   /* soft phrase divider */
  --line:         #D9D0C2;   /* hairlines and card borders */

  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, "Times New Roman", serif;
  --sans:  system-ui, -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;

  --ease: cubic-bezier(0.33, 0.0, 0.2, 1);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
}

/* --------------------------------------------------------------------------
   Stage
   -------------------------------------------------------------------------- */

.opening-exhibit {
  min-height: 100dvh;
  display: grid;
  place-items: center;
  padding: 3rem 1.5rem 9rem;   /* room for the fixed controls */
}

.exhibit-panel {
  display: none;
  max-width: 42rem;
  width: 100%;
  text-align: center;
}

.exhibit-panel.is-active {
  display: block;
  animation: panel-in 900ms var(--ease) both;
}

@keyframes panel-in {
  from { opacity: 0; transform: translateY(0.5rem); }
  to   { opacity: 1; transform: none; }
}

/* --------------------------------------------------------------------------
   Reveals within a panel
   -------------------------------------------------------------------------- */

[data-reveal] {
  opacity: 0;
  transform: translateY(0.4rem);
  transition: opacity 1100ms var(--ease), transform 1100ms var(--ease);
}

[data-reveal].is-shown {
  opacity: 1;
  transform: none;
}

/* A plain line that yields to its marked twin (panels 5 and 7) */
[data-swap-out].is-hidden-away {
  opacity: 0.14;
  transform: none;
}

/* --------------------------------------------------------------------------
   Type
   -------------------------------------------------------------------------- */

.display-line {
  font-family: var(--serif);
  font-size: clamp(1.7rem, 4.5vw, 2.6rem);
  font-weight: 400;
  line-height: 1.35;
  margin: 0 0 1rem;
  text-wrap: balance;
}

.display-line.small {
  font-size: clamp(1.3rem, 3.5vw, 1.9rem);
}

.invitation {
  color: var(--ink);
}

.demo-word {
  font-family: var(--serif);
  font-size: clamp(2rem, 6vw, 3.2rem);
  line-height: 1.3;
  margin: 0.4em 0;
  letter-spacing: 0.01em;
}

.demo-sentence {
  font-family: var(--serif);
  font-size: clamp(1.4rem, 4vw, 2.1rem);
  line-height: 1.65;
  margin: 0.8em 0;
  text-wrap: balance;
}

.dot {
  color: var(--ink-soft);
  padding: 0 0.02em;
}

.takeaway {
  font-family: var(--sans);
  font-size: clamp(1rem, 2.5vw, 1.15rem);
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--ink);
  margin-top: 2.4rem;
}

.takeaway.inline { margin-top: 0.9rem; }

.caption {
  font-family: var(--sans);
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.panel-title {
  font-family: var(--serif);
  font-size: clamp(1.5rem, 4vw, 2.1rem);
  font-weight: 400;
  line-height: 1.3;
  margin: 0 0 1.4rem;
  text-wrap: balance;
}

/* --------------------------------------------------------------------------
   Stress: warm glow + weight change (never color alone)
   -------------------------------------------------------------------------- */

.stress {
  font-weight: 700;
  color: var(--ink);
  text-shadow:
    0 0 14px var(--glow-halo),
    0 0 30px var(--glow-halo);
  transition: text-shadow 900ms var(--ease);
}

/* Rhythmic beats pulse gently, like breathing */
.beat.is-pulsing {
  animation: beat-breathe 1400ms var(--ease);
}

@keyframes beat-breathe {
  0%   { text-shadow: 0 0 14px var(--glow-halo), 0 0 30px var(--glow-halo); }
  35%  { text-shadow: 0 0 22px var(--glow-halo), 0 0 46px var(--glow-halo);
         color: #4A3A20; }
  100% { text-shadow: 0 0 14px var(--glow-halo), 0 0 30px var(--glow-halo); }
}

/* --------------------------------------------------------------------------
   Phrase boundaries
   -------------------------------------------------------------------------- */

.phrase-boundary {
  color: var(--boundary);
  font-weight: 300;
  padding: 0 0.18em;
}

/* --------------------------------------------------------------------------
   Panel 5 — beat patterns, one at a time
   The two steps share one stage (a single grid cell): step one clears
   away completely before step two begins, so the learner sees exactly
   one beat pattern at a time — never a faded example lingering in the
   background. No dividers inside the lines: tall bars could be mistaken
   for phrase boundaries, so the cue lines separate beat groups with
   interpuncts.
   -------------------------------------------------------------------------- */

.rhythm-steps {
  display: grid;
}

.rhythm-step {
  grid-area: 1 / 1;             /* both steps occupy the same spot */
  align-self: center;
  transition: opacity 1100ms var(--ease), visibility 0s linear 1100ms;
}

.rhythm-step.is-cleared {
  opacity: 0;
  visibility: hidden;           /* gone, not faded-in-the-background */
  pointer-events: none;
}

/* The sentences sit a step below the default demo size, so the beat
   cue beneath them is easy to see. */
.rhythm-step .demo-sentence {
  font-size: clamp(1.25rem, 3.2vw, 1.75rem);
}

/* The ta-DUM / DUM-ta line: only there to help learners notice the beat. */
.beat-cue {
  font-family: var(--sans);
  font-size: clamp(1rem, 2.6vw, 1.25rem);
  letter-spacing: 0.05em;
  color: var(--ink-soft);
  margin: 0.5em 0 0.45em;
}

.beat-caption { margin: 0.6rem 0 0; }

/* --------------------------------------------------------------------------
   Panel 7 — intonation (sound is the exhibit; visuals only guide)
   -------------------------------------------------------------------------- */

.audio-row {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 1.6rem;
}

.audio-button {
  font-family: var(--serif);
  font-size: clamp(1.2rem, 3vw, 1.6rem);
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--boundary);
  border-radius: 999px;
  padding: 0.55em 1.1em;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.55em;
  transition: border-color 300ms var(--ease), box-shadow 300ms var(--ease);
}

.audio-button:hover,
.audio-button:focus-visible {
  border-color: var(--glow);
  box-shadow: 0 0 0 4px var(--glow-halo);
}

.audio-button.was-played .play-glyph { color: var(--glow); }

/* The voice currently sounding wears the same warm ring as a press. */
.audio-button.is-sounding {
  border-color: var(--glow);
  box-shadow: 0 0 0 4px var(--glow-halo);
}

.play-glyph {
  font-family: var(--sans);
  font-size: 0.7em;
  color: var(--ink-soft);
}

/* The transcript stays available for accessibility without
   dominating the screen: folded into a small disclosure. */
.audio-transcript-details {
  max-width: 34rem;
  margin: 1.6rem auto 0;
}

.audio-transcript-details summary {
  cursor: pointer;
  font-family: var(--sans);
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.audio-transcript-details summary:hover,
.audio-transcript-details summary:focus-visible {
  color: var(--ink);
}

.audio-transcript-details p { margin: 0.5rem 0 0; }

#audio-takeaway { margin-top: 1.4rem; }
#audio-takeaway p { margin: 0.25em 0; }

/* --------------------------------------------------------------------------
   Panel 8 — hidden architecture
   -------------------------------------------------------------------------- */

.architecture {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.15rem;
}

.arch-level {
  font-family: var(--serif);
  font-size: clamp(1.3rem, 3.4vw, 1.8rem);
  margin: 0.1em 0;
}

.arch-level:first-child { font-weight: 700; }  /* Meaning crowns the stack */

.arch-arrow {
  color: var(--ink-soft);
  font-size: 1rem;
  margin: 0;
}

/* --------------------------------------------------------------------------
   Panel 9 — brand
   -------------------------------------------------------------------------- */

.brand {
  font-family: var(--serif);
  font-size: clamp(2.4rem, 7vw, 4rem);
  font-weight: 400;
  letter-spacing: 0.01em;
  margin: 0 0 1rem;
}

.brand-subtitle {
  font-family: var(--sans);
  font-size: clamp(1rem, 2.6vw, 1.2rem);
  color: var(--ink-soft);
  max-width: 30rem;
  margin: 0 auto;
  line-height: 1.6;
}

/* --------------------------------------------------------------------------
   Panel 10 — Sputnik
   -------------------------------------------------------------------------- */

.sputnik-scene {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2.4rem;
  flex-wrap: wrap;
}

.sputnik {
  width: min(170px, 40vw);
  height: auto;
  color: var(--ink);
  flex-shrink: 0;
}

.sputnik-collar { stroke: var(--glow); }

.sputnik-speech { text-align: left; max-width: 22rem; }

@media (max-width: 560px) {
  .sputnik-speech { text-align: center; }
}

/* --------------------------------------------------------------------------
   Controls
   -------------------------------------------------------------------------- */

.exhibit-controls {
  position: fixed;
  inset-inline: 0;
  bottom: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.6rem;
  padding: 1.2rem 1.5rem 1.6rem;
  background: linear-gradient(to top, var(--paper) 65%, transparent);
}

.panel-counter {
  letter-spacing: 0.06em;
}

.continue-button {
  font-family: var(--sans);
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--paper);
  background: var(--ink);
  border: none;
  border-radius: 999px;
  padding: 0.75em 2.6em;
  cursor: pointer;
  transition: background 300ms var(--ease), box-shadow 300ms var(--ease);
}

.continue-button:hover,
.continue-button:focus-visible {
  background: #171512;
  box-shadow: 0 0 0 4px var(--glow-halo);
}

.skip-link {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--ink-soft);
  background: none;
  border: none;
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 3px;
  padding: 0.2em 0.5em;
}

.skip-link:hover,
.skip-link:focus-visible { color: var(--ink); }

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

/* --------------------------------------------------------------------------
   Reduced motion: everything appears at once, nothing pulses
   -------------------------------------------------------------------------- */

@media (prefers-reduced-motion: reduce) {
  .exhibit-panel.is-active { animation: none; }
  [data-reveal] { transition: none; transform: none; }
  .beat.is-pulsing { animation: none; }
  .stress { transition: none; }
  .audio-button, .continue-button, .transport-button { transition: none; }
  /* The three beat-pattern steps flow down the page in order, all
     present at once — nothing moves, nothing vanishes. (The script
     also skips scheduling any clears under reduced motion.) */
  .rhythm-steps { display: block; }
  .rhythm-step { transition: none; }
  .rhythm-step.is-cleared { opacity: 1; visibility: visible; }
}

/* --------------------------------------------------------------------------
   Completion safety rules — once the exhibit is complete, no stray
   attribute or script hiccup can leave it on screen; and the homepage
   can never leak through while it is still marked hidden.
   -------------------------------------------------------------------------- */

body.exhibit-complete #opening-exhibit,
body.exhibit-complete .exhibit-controls {
  display: none;
}

#site-content[hidden] {
  display: none;
}

/* --------------------------------------------------------------------------
   Transport — the exhibit plays itself; these keep the visitor in charge
   -------------------------------------------------------------------------- */

.transport {
  display: flex;
  align-items: center;
  gap: 0.9rem;
}

.transport-button {
  min-height: 2.6rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--sans);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--boundary);
  border-radius: 999px;
  padding: 0.45em 1.2em;
  cursor: pointer;
  transition: border-color 300ms var(--ease), box-shadow 300ms var(--ease);
}

.transport-button:hover,
.transport-button:focus-visible {
  border-color: var(--glow);
  box-shadow: 0 0 0 4px var(--glow-halo);
}

.transport-button:disabled {
  opacity: 0.3;
  cursor: default;
  border-color: var(--boundary);
  box-shadow: none;
}

.transport-button[hidden] { display: none; }

/* --------------------------------------------------------------------------
   Panel 10 — Sputnik's portrait (a photograph now, not a line drawing)
   -------------------------------------------------------------------------- */

img.sputnik {
  border-radius: 14px;
  box-shadow: 0 12px 32px rgba(46, 43, 39, 0.18);
}