/* Page layout (CONTENT.md §3). Page-level structure only — it consumes the theme
 * tokens (theme-<name>.css) and never styles converter internals.
 *
 * Pivot layout: the converter owns the primary page; the lecture/exhibition
 * material lives in a right-side CURTAIN opened by a fixed bottom-right action
 * button. The converter renders inside its own Shadow DOM, so these global rules
 * do not leak into it (CONTENT.md §2). We forward only --accent and --radius to
 * the converter host (#converter), the sole styling coupling permitted (§5).
 */

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.page {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 22px 96px;
}

a {
  color: var(--accent);
  text-underline-offset: 2px;
}

/* Skip link for keyboard users (CONTENT.md §5 — keyboard-navigable). */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent);
  color: var(--accent-contrast);
  padding: 10px 16px;
  border-radius: 0 0 var(--radius) 0;
  z-index: 10;
}
.skip-link:focus { left: 0; }

/* ---- Sticky site header (brand + Home + source) ------------------------- */
/* Matches garutyunov.com layout. Sits below the curtain system in the stack
 * (toggle 40 / backdrop 45 / curtain 50) so the curtain covers it when open. */

.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  height: 56px;
  padding: 0 max(16px, env(safe-area-inset-left)) 0 max(16px, env(safe-area-inset-right));
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.site-header .brand {
  font-size: 15px;
  font-weight: 600;
  color: var(--fg);
  text-decoration: none;
  transition: color 0.15s ease;
}
.site-header .brand:hover { color: var(--muted); }
.site-nav { display: flex; align-items: center; gap: 20px; }
.site-nav a {
  font-size: 14px;
  color: var(--muted);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  transition: color 0.15s ease;
}
.site-nav a:hover { color: var(--fg); }
.site-nav svg { width: 18px; height: 18px; display: block; }

/* ---- Primary header: the converter is the headline (§3.2) --------------- */

.app-header {
  padding: 44px 0 28px;
}
.app-header h1 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(34px, 6vw, 52px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  margin: 0;
}
.app-intro {
  max-width: 62ch;
  color: var(--muted);
  font-size: 19px;
  margin: 16px 0 0;
}

/* ---- Converter section (§3.2) ------------------------------------------ */

.converter-section { padding: 0 0 32px; }

/* The converter host. Only --accent and --radius are forwarded (CONTENT.md §5).
 * Those inherit from :root automatically. The converter ALSO happens to read
 * --bg/--surface/--text/--muted/--border (its own optional tokens), and our
 * page tokens share some of those names — so we reset them to `initial` here.
 * That makes the converter fall back to its own (dark) defaults, keeping the
 * page↔converter coupling to exactly --accent and --radius. */
#converter {
  --bg: initial;
  --surface: initial;
  --text: initial;
  --muted: initial;
  --border: initial;
  display: block;
  margin-top: 8px;
}

.converter-note {
  margin: 0 0 24px;
  padding: 14px 16px;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  font-size: 15px;
  color: var(--muted);
}

/* ---- Action button: bottom-right corner -------------------------------- */

.curtain-toggle {
  position: fixed;
  right: max(20px, env(safe-area-inset-right));
  bottom: max(20px, env(safe-area-inset-bottom));
  z-index: 40;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  padding: 0;
  background: var(--accent);
  color: var(--accent-contrast);
  border: 0;
  border-radius: 50%;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  cursor: pointer;
  transition: filter 0.15s ease, transform 0.15s ease;
}
.curtain-toggle:hover { filter: brightness(1.08); }
.curtain-toggle:active { transform: translateY(1px); }
.curtain-toggle:focus-visible { outline: 2px solid var(--fg); outline-offset: 3px; }
.curtain-toggle-icon { flex: none; }

/* Hide the button while the curtain is open (the curtain has its own close). */
body.curtain-open .curtain-toggle {
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
}

/* ---- Curtain (right-side drawer) --------------------------------------- */

.curtain-backdrop {
  position: fixed;
  inset: 0;
  z-index: 45;
  background: rgba(0, 0, 0, 0.5);
  opacity: 0;
  transition: opacity 0.3s ease;
}
.curtain-backdrop.is-open { opacity: 1; }

.curtain {
  position: fixed;
  top: 0;
  right: 0;
  z-index: 50;
  width: min(560px, 100%);
  height: 100%;
  background: var(--bg);
  border-left: 1px solid var(--border);
  box-shadow: -16px 0 40px rgba(0, 0, 0, 0.4);
  display: flex;
  flex-direction: column;
  transform: translateX(100%);
  transition: transform 0.32s cubic-bezier(0.4, 0, 0.2, 1);
  visibility: hidden;
}
.curtain.is-open {
  transform: translateX(0);
  visibility: visible;
}

.curtain-head {
  flex: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 22px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
}
.curtain-heading {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 19px;
  letter-spacing: -0.01em;
  color: var(--fg);
}
.curtain-close {
  flex: none;
  width: 38px;
  height: 38px;
  border: 1px solid var(--border);
  border-radius: 50%;
  background: var(--bg-elev);
  color: var(--fg);
  font-size: 22px;
  line-height: 1;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.curtain-close:hover { border-color: var(--accent); }
.curtain-close:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.curtain-body {
  flex: 1;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 0 22px 56px;
}

/* ---- Curtain sections -------------------------------------------------- */

.curtain-body section { padding: 36px 0; border-bottom: 1px solid var(--border); }
.curtain-body footer { padding: 36px 0 0; color: var(--muted); font-size: 15px; }

.curtain-body section > h3,
.curtain-body footer > h3 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(22px, 4vw, 28px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin: 0 0 8px;
}
.curtain-body footer > h3 { font-size: 20px; color: var(--fg); }

/* ---- History & science (§3.3 / §4) ------------------------------------- */

.history > h3 { margin-bottom: 22px; }

.history-entry { padding: 24px 0; border-top: 1px solid var(--border); }
.history-entry:first-of-type { border-top: 0; padding-top: 0; }
.history-entry h4 {
  font-family: var(--font-display);
  font-size: 21px;
  line-height: 1.25;
  margin: 0 0 10px;
}
.prose { max-width: 68ch; }
.prose p { margin: 0 0 14px; }
.prose p:last-child { margin-bottom: 0; }
.prose em { font-style: italic; }
.prose strong { font-weight: 700; color: var(--fg); }

.entry-refs {
  margin: 16px 0 0;
  font-size: 14px;
  color: var(--muted);
}
.entry-refs .ref-chip {
  display: inline-block;
  color: var(--accent);
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 2px 10px;
  margin: 0 6px 6px 0;
}
.entry-refs .ref-chip:hover { border-color: var(--accent); }

/* ---- About (§3.4) ------------------------------------------------------ */

.credits {
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 6px;
}
.credits div { display: flex; gap: 10px; }
.credits dt, .credits .k {
  color: var(--muted);
  min-width: 90px;
  font-size: 15px;
}
.credits .v { font-weight: 600; }

/* ---- Footer / references (§3.5) ---------------------------------------- */

.references { margin: 0 0 28px; padding-left: 22px; display: grid; gap: 10px; }
.references li { line-height: 1.5; }
.references a { word-break: break-word; }
.footer-meta { border-top: 1px solid var(--border); padding-top: 20px; }
.footer-links { list-style: none; padding: 0; margin: 0 0 12px; display: flex; flex-wrap: wrap; gap: 18px; }
.footer-links a { text-decoration: none; }
.footer-links a:hover { text-decoration: underline; }

/* ---- Accessibility: respect reduced motion (CONTENT.md §5) -------------- */

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; }
}