/* SCROLLFILM — styles. Dark cinematic theme; chapters float over a fixed WebGL canvas. */

:root {
  --bg: #05070c;
  --ink: #eef2f7;
  --muted: #9aa7bd;
  --amber: #ffb454;
  --cyan: #57e6ff;
  --paper: #f5f1e8;
  --paper-ink: #1a1d24;
  --font-display: "Space Grotesk", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}

html { scroll-behavior: auto; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-display);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* ---------- Layer 0: the film ---------- */
#film {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  z-index: 0;
  display: block;
}

.vignette {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  background: radial-gradient(ellipse at center, transparent 55%, rgba(0, 0, 0, 0.55) 100%);
}

/* Chapter-transition light flash (driven from film.js) */
.flash {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  opacity: 0;
  background: radial-gradient(ellipse at center, rgba(255,240,210,0.85) 0%, rgba(255,200,120,0.30) 45%, transparent 75%);
}

/* ---------- Layer 1: real HTML ---------- */
#content { position: relative; z-index: 2; }

.chapter { min-height: 135vh; position: relative; }
.chapter:first-child { min-height: 115vh; }

.chapter-inner {
  position: sticky;
  top: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 0 6vw;
  opacity: 0;
  transform: translateY(36px);
  transition: opacity 0.7s ease, transform 0.7s ease;
  pointer-events: none;
}

.chapter.is-active .chapter-inner { opacity: 1; transform: translateY(0); }

.eyebrow {
  font-size: 0.8rem;
  letter-spacing: 0.35em;
  text-transform: uppercase;
  color: var(--amber);
  margin: 0 0 1.2rem;
}

.mega {
  font-size: clamp(3.5rem, 14vw, 10rem);
  line-height: 0.95;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 1.5rem;
  text-shadow: 0 4px 60px rgba(0, 0, 0, 0.8);
}
.mega.small { font-size: clamp(2.8rem, 10vw, 7rem); }

h2 {
  font-size: clamp(2rem, 6vw, 4rem);
  line-height: 1.05;
  letter-spacing: -0.01em;
  margin: 0 0 1.2rem;
  text-shadow: 0 2px 40px rgba(0, 0, 0, 0.85);
  max-width: 16em;
}

.lede {
  font-size: clamp(1.1rem, 2.6vw, 1.6rem);
  color: var(--ink);
  line-height: 1.5;
  margin: 0;
  text-shadow: 0 2px 24px rgba(0, 0, 0, 0.9);
}

.body-copy {
  font-size: clamp(1rem, 2.2vw, 1.25rem);
  line-height: 1.65;
  color: #d7dee9;
  max-width: 34em;
  margin: 0;
  text-shadow: 0 2px 24px rgba(0, 0, 0, 0.9);
}
.body-copy code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: rgba(255, 255, 255, 0.1);
  padding: 0.15em 0.45em;
  border-radius: 4px;
}
.body-copy em { color: var(--cyan); font-style: normal; font-weight: 500; }

.scroll-hint {
  margin-top: 3rem;
  color: var(--muted);
  font-size: 0.9rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}
.scroll-hint-arrow {
  display: inline-block;
  animation: bob 1.8s ease-in-out infinite;
  color: var(--amber);
}
@keyframes bob { 0%, 100% { transform: translateY(-4px); } 50% { transform: translateY(4px); } }

/* ---------- HUD: film-player chrome ---------- */
.hud {
  position: fixed;
  left: 0; right: 0; bottom: 0;
  z-index: 5;
  padding: 0.7rem 1.2rem 0.9rem;
  pointer-events: none;
  background: linear-gradient(transparent, rgba(0, 0, 0, 0.55));
}
.hud-row {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  font-size: 0.75rem;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.5rem;
}
.hud-title { color: var(--ink); font-weight: 700; }
.hud-fps { margin-left: auto; font-family: var(--font-mono); letter-spacing: 0.05em; }
.hud-fps.good { color: #7dffa8; }
.hud-fps.warn { color: var(--amber); }
.hud-track {
  position: relative;
  height: 3px;
  background: rgba(255, 255, 255, 0.18);
  border-radius: 2px;
}
.hud-bar {
  position: absolute; left: 0; top: 0; bottom: 0;
  width: 0%;
  background: linear-gradient(90deg, var(--cyan), var(--amber));
  border-radius: 2px;
}
.hud-knob {
  position: absolute; top: 50%;
  width: 11px; height: 11px;
  border-radius: 50%;
  background: var(--ink);
  transform: translate(-50%, -50%);
  left: 0%;
  box-shadow: 0 0 12px rgba(255, 180, 84, 0.9);
}

/* ---------- Blueprint: the reverse-engineering section ---------- */
.blueprint {
  position: relative;
  z-index: 2;
  background: var(--paper);
  color: var(--paper-ink);
  padding: clamp(4rem, 10vh, 7rem) 6vw;
}
.blueprint-inner { max-width: 1020px; margin: 0 auto; }
.eyebrow.dark { color: #b07a1e; }
.blueprint h2 { text-shadow: none; color: var(--paper-ink); }
.body-copy.dark { color: #3c414d; text-shadow: none; }
.body-copy.dark em { color: #0b6e7f; }

.trick-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.25rem;
  margin: 2.5rem 0;
}
.trick {
  background: #fff;
  border: 1px solid #e3dccb;
  border-radius: 14px;
  padding: 1.5rem;
  box-shadow: 0 10px 30px rgba(26, 29, 36, 0.06);
}
.trick h3 { font-size: 1.05rem; margin: 0 0 0.7rem; line-height: 1.35; }
.trick-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  background: var(--paper-ink);
  color: var(--paper);
  border-radius: 6px;
  padding: 0.2em 0.5em;
  margin-right: 0.5em;
}
.trick p { font-size: 0.95rem; line-height: 1.6; color: #3c414d; margin: 0 0 1rem; }
.trick p code, .lab code, .perf code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: #efe9da;
  padding: 0.1em 0.4em;
  border-radius: 4px;
}
.trick pre {
  background: #14161c;
  color: #d6e2f0;
  border-radius: 10px;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.6;
  margin: 0 0 1rem;
}
.trick pre code { background: none; padding: 0; }

.btn {
  font-family: var(--font-display);
  font-weight: 500;
  font-size: 0.9rem;
  background: var(--paper-ink);
  color: var(--paper);
  border: none;
  border-radius: 999px;
  padding: 0.65rem 1.4rem;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.15s ease;
}
.btn:hover { background: #000; transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn[aria-pressed="true"] { background: #b07a1e; }

.lab, .perf {
  background: #fff;
  border: 1px solid #e3dccb;
  border-radius: 14px;
  padding: 1.75rem;
  margin-bottom: 1.25rem;
}
.lab h3, .perf h3 { margin: 0 0 0.6rem; font-size: 1.2rem; }
.lab p, .perf p, .perf li { color: #3c414d; line-height: 1.6; }
.lab-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.25rem;
  margin: 1rem 0;
}
.fps-readout {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  background: #14161c;
  color: #d6e2f0;
  padding: 0.6rem 1.1rem;
  border-radius: 10px;
}
.fps-readout strong { color: #7dffa8; font-size: 1.2em; }
.fps-note { color: #9aa7bd; font-size: 0.8em; }
.perf ul { margin: 0.5rem 0 0; padding-left: 1.2rem; }
.perf li { margin-bottom: 0.55rem; }
.fineprint { font-size: 0.85rem; color: #8a8fa0; }

.footer {
  position: relative;
  z-index: 2;
  background: #0a0c12;
  color: var(--muted);
  text-align: center;
  padding: 3rem 6vw;
  font-size: 0.95rem;
}
.footer a { color: var(--cyan); }
.footer .fineprint { margin-top: 0.5rem; }

/* ---------- X-ray mode ---------- */
.xray-tag { display: none; }
body.xray #film { outline: 3px dashed #ff3b30; outline-offset: -3px; }
body.xray .xray-tag-film {
  display: block;
  position: fixed;
  top: 12px; left: 12px;
  z-index: 9;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  background: #ff3b30;
  color: #fff;
  padding: 0.4rem 0.7rem;
  border-radius: 6px;
}
body.xray .chapter-inner { outline: 2px dashed var(--cyan); outline-offset: -2px; }
body.xray .blueprint { outline: 3px dashed var(--cyan); outline-offset: -3px; }
body.xray .hud { outline: 2px dashed var(--amber); }

/* ---------- No-WebGL fallback ---------- */
.nogl {
  position: fixed;
  inset: auto 0 0 0;
  z-index: 20;
  background: #3a2b00;
  color: #ffe9bd;
  padding: 1rem;
  text-align: center;
  font-size: 0.95rem;
}
body.no-webgl .chapter-inner { opacity: 1; transform: none; }
body.no-webgl #film, body.no-webgl .vignette, body.no-webgl .hud { display: none; }

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  .scroll-hint-arrow { animation: none; }
  .chapter-inner { transition: none; }
}

/* ---------- Small screens ---------- */
@media (max-width: 640px) {
  .chapter-inner { padding: 0 8vw; }
  .hud-row { font-size: 0.65rem; }
  .trick-grid { grid-template-columns: 1fr; }
}