:root {
  --page: #fff;
  --ink: #0b0b0c;
  --muted: rgba(11, 11, 12, 0.62);
  --line: rgba(11, 11, 12, 0.13);
  --soft: #f5f5f3;
  --pill: rgba(255, 255, 255, 0.86);
  color-scheme: light;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  letter-spacing: -0.022em;
}
a { color: inherit; text-decoration-thickness: 0.07em; text-underline-offset: 0.17em; }
img { display: block; max-width: 100%; }
button { font: inherit; }
.site-shell { min-height: 100vh; }
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 1.5rem;
  max-width: 1180px;
  margin: 0 auto;
  padding: 1.35rem clamp(1.15rem, 4vw, 2rem);
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(20px);
}
.logo { font-weight: 700; text-decoration: none; font-size: 1.02rem; }
.main-nav { display: flex; justify-content: center; gap: 1.15rem; font-size: 0.86rem; color: var(--muted); }
.main-nav a { text-decoration: none; }
.efact-actions { display: flex; gap: 0.55rem; align-items: center; }
.efact-actions a { font-size: 0.82rem; text-decoration: none; }
.efact-actions a:last-child { padding: 0.62rem 0.9rem; border-radius: 999px; background: #111; color: #fff; font-weight: 650; }
.menu-toggle { display: none; width: 2.25rem; height: 2.25rem; border: 1px solid var(--line); border-radius: 50%; background: #fff; }
.menu-toggle span { display: block; width: 0.9rem; height: 1.5px; margin: 0.22rem auto; background: #111; }
.openai-product-article article { max-width: 1040px; margin: 0 auto; padding: 0 clamp(1.15rem, 4vw, 2rem) 5rem; }
.openai-article-hero { padding: clamp(5.5rem, 13vw, 10rem) 0 clamp(2.1rem, 5vw, 4rem); text-align: center; }
.openai-article-hero p { margin: 0 0 1.1rem; font-size: clamp(0.9rem, 1.6vw, 1.05rem); color: var(--muted); letter-spacing: -0.01em; }
.openai-article-hero h1 {
  max-width: 13.5ch;
  margin: 0 auto;
  font-size: clamp(3.45rem, 9.4vw, 7.8rem);
  line-height: 0.91;
  font-weight: 650;
  letter-spacing: -0.078em;
}
.efact-product-hero-visual { margin: 0; padding: 0 0 clamp(1.4rem, 3vw, 2rem); }
.efact-product-hero-visual picture {
  display: block;
  overflow: hidden;
  border-radius: clamp(1rem, 2.4vw, 1.65rem);
  background: #dfe4e5;
  transform: translateZ(0);
}
.efact-product-hero-visual img {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  transform: scale(1.001);
  transition: transform 900ms cubic-bezier(.2,.7,.2,1), filter 900ms cubic-bezier(.2,.7,.2,1);
}
.efact-product-hero-visual figcaption {
  max-width: 40rem;
  margin: 0 auto;
  padding-top: 0.95rem;
  color: var(--muted);
  font-size: 0.96rem;
  line-height: 1.48;
  text-align: center;
}
@media (hover: hover) and (pointer: fine) {
  .efact-product-hero-visual:hover img { transform: scale(1.018); filter: saturate(1.02) contrast(1.015); }
}
.openai-article-actions {
  display: flex;
  justify-content: center;
  gap: 0.72rem;
  flex-wrap: wrap;
  padding: clamp(0.6rem, 2vw, 1rem) 0 clamp(3.2rem, 6vw, 5rem);
}
.openai-article-actions a {
  display: inline-flex;
  min-height: 2.55rem;
  align-items: center;
  padding: 0 1.1rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fff;
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 600;
  box-shadow: 0 0.7rem 2rem rgba(0,0,0,0.035);
  transition: transform 220ms ease, border-color 220ms ease, background 220ms ease;
}
.openai-article-actions a.is-primary { background: #111; color: #fff; border-color: #111; }
.openai-article-actions a:focus-visible, .openai-article-actions a:hover { transform: translateY(-1px); border-color: rgba(0,0,0,0.35); }
.openai-article-body { max-width: 710px; margin: 0 auto; }
.openai-article-body > p {
  margin: 0 0 1.35rem;
  color: rgba(11,11,12,0.76);
  font-size: clamp(1.12rem, 2vw, 1.42rem);
  line-height: 1.44;
  letter-spacing: -0.032em;
}
.openai-article-body h2 {
  margin: clamp(3.8rem, 7vw, 6rem) 0 1rem;
  font-size: clamp(2.3rem, 5.4vw, 4.5rem);
  line-height: 0.96;
  font-weight: 650;
  letter-spacing: -0.064em;
}
.openai-article-body blockquote {
  margin: clamp(3rem, 6vw, 5rem) 0;
  padding: 0;
  border: 0;
  color: #111;
  font-size: clamp(2rem, 4.2vw, 3.6rem);
  line-height: 1.02;
  font-weight: 650;
  letter-spacing: -0.06em;
}
.openai-product-flow {
  margin: clamp(3rem, 6vw, 5rem) 0;
  padding: clamp(1.6rem, 4vw, 2.4rem) 0 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.openai-product-flow h3 { margin: 0 0 1.3rem; color: var(--muted); font-size: 0.9rem; font-weight: 650; letter-spacing: 0.04em; text-transform: uppercase; }
.openai-product-flow ol { list-style: none; margin: 0; padding: 0; }
.openai-product-flow li {
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: clamp(0.85rem, 2vw, 1.3rem);
  padding: 1.22rem 0;
  border-top: 1px solid rgba(11,11,12,0.09);
  transition: opacity 220ms ease, transform 220ms ease;
}
.openai-product-flow li:first-child { border-top: 0; }
.openai-product-flow li:hover { transform: translateX(0.18rem); }
.openai-product-flow span { color: var(--muted); font-size: 0.95rem; }
.openai-product-flow strong { display: block; font-size: clamp(1.22rem, 2.4vw, 1.65rem); line-height: 1.05; letter-spacing: -0.04em; }
.openai-product-flow p { margin: 0.35rem 0 0; color: var(--muted); font-size: 1rem; line-height: 1.45; letter-spacing: -0.012em; }
.openai-article-cta {
  max-width: 710px;
  margin: clamp(4rem, 8vw, 7rem) auto 0;
  padding: clamp(2.6rem, 6vw, 5rem) 0;
  border-top: 1px solid var(--line);
  text-align: center;
}
.openai-article-cta h2 { margin: 0 auto 1.2rem; max-width: 11ch; font-size: clamp(2.6rem, 6.5vw, 5.5rem); line-height: 0.94; letter-spacing: -0.07em; font-weight: 650; }
.openai-article-cta a { display: inline-flex; align-items: center; min-height: 2.6rem; padding: 0 1.15rem; border-radius: 999px; background: #111; color: #fff; text-decoration: none; font-weight: 650; }
.site-footer {
  max-width: 1040px;
  margin: 0 auto;
  padding: 3rem clamp(1.15rem, 4vw, 2rem) 4rem;
  border-top: 1px solid var(--line);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
}
.site-footer h4 { margin: 0 0 0.8rem; font-size: 0.86rem; }
.site-footer a { display: block; margin: 0.5rem 0; color: var(--muted); text-decoration: none; font-size: 0.88rem; }
.bottom-bar { display: none; }
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 700ms ease, transform 700ms cubic-bezier(.2,.7,.2,1); }
.reveal.is-visible { opacity: 1; transform: translateY(0); }
@media (max-width: 820px) {
  .site-header { grid-template-columns: auto auto; justify-content: space-between; padding-top: 1rem; padding-bottom: 1rem; }
  .menu-toggle { display: block; }
  .main-nav, .efact-actions { display: none; }
  body.nav-open .main-nav {
    position: fixed;
    inset: 4.2rem 1rem auto;
    display: grid;
    justify-content: stretch;
    gap: 0;
    padding: 0.7rem;
    border: 1px solid var(--line);
    border-radius: 1.1rem;
    background: rgba(255,255,255,0.97);
    box-shadow: 0 2rem 4rem rgba(0,0,0,0.12);
  }
  body.nav-open .main-nav a { padding: 0.85rem; border-bottom: 1px solid rgba(11,11,12,0.07); font-size: 1rem; }
  body.nav-open .main-nav a:last-child { border-bottom: 0; }
  .openai-product-article article { padding-bottom: 3.5rem; }
  .openai-article-hero { padding-top: 5rem; text-align: left; }
  .openai-article-hero h1 { margin-left: 0; max-width: 10.6ch; }
  .efact-product-hero-visual { margin-left: -0.15rem; margin-right: -0.15rem; }
  .efact-product-hero-visual picture { border-radius: 0.92rem; }
  .efact-product-hero-visual figcaption { text-align: left; }
  .openai-article-actions { justify-content: flex-start; padding-bottom: 3.2rem; }
  .openai-product-flow li { grid-template-columns: 2.35rem 1fr; }
  .site-footer { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
  .openai-article-hero { padding-top: 4.25rem; }
  .openai-article-hero h1 { font-size: clamp(3.1rem, 16vw, 4.4rem); max-width: 9.7ch; }
  .openai-article-body > p { font-size: 1.12rem; }
  .openai-article-body h2 { font-size: clamp(2.4rem, 12vw, 3.35rem); }
  .openai-article-actions a { flex: 1 1 auto; justify-content: center; }
  .site-footer { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal { opacity: 1; transform: none; }
}

/* 20260908ae: above-the-fold content must never be hidden by motion. */
.reveal {
  opacity: 1 !important;
  transform: none !important;
  animation: efactCleanReveal 620ms cubic-bezier(.2,.7,.2,1) both;
}
.openai-article-hero.reveal { animation-delay: 40ms; }
.efact-product-hero-visual.reveal { animation-delay: 120ms; }
.openai-article-actions.reveal { animation-delay: 190ms; }
@keyframes efactCleanReveal {
  from { opacity: 0; transform: translateY(14px); }
  to { opacity: 1; transform: translateY(0); }
}
@media (prefers-reduced-motion: reduce) {
  .reveal { animation: none !important; }
}

/* 20260908af: OpenAI article rhythm: product visual first, explanation second. */
.efact-product-hero-visual {
  margin-top: clamp(5rem, 10vw, 8rem);
}
.openai-article-hero {
  padding: clamp(1.45rem, 3.8vw, 2.8rem) 0 clamp(1.8rem, 4.2vw, 3.4rem) !important;
}
.openai-article-hero h1 {
  max-width: 15ch;
  font-size: clamp(2.75rem, 7vw, 6.3rem);
}
@media (max-width: 820px) {
  .efact-product-hero-visual { margin-top: 4.8rem; }
  .openai-article-hero { padding-top: 1.2rem !important; }
  .openai-article-hero h1 { max-width: 10.5ch; }
}
@media (max-width: 480px) {
  .efact-product-hero-visual { margin-top: 4rem; }
  .openai-article-hero h1 { font-size: clamp(2.7rem, 13.2vw, 3.7rem); max-width: 9.8ch; }
}

/* 20260908ag: on mobile the generated product image must show the full device, not crop into the screen. */
@media (max-width: 820px) {
  .efact-product-hero-visual picture {
    background: #e1e6e7;
  }
  .efact-product-hero-visual img {
    height: auto !important;
    aspect-ratio: auto !important;
    object-fit: contain !important;
  }
}

/* 20260908ah: mobile uses portrait product crops and less cramped typography. */
@media (max-width: 820px) {
  .efact-product-hero-visual img {
    width: 100% !important;
    height: auto !important;
  }
  .openai-article-hero h1 {
    letter-spacing: -0.055em !important;
    font-weight: 640 !important;
  }
}
@media (max-width: 480px) {
  .openai-article-hero h1 {
    letter-spacing: -0.052em !important;
    line-height: 0.94 !important;
  }
}