:root { color-scheme: dark; }

* { box-sizing: border-box; }

html, body { margin: 0; background: #000; }

body { overflow-x: hidden; }

.back-home {
  position: fixed;
  z-index: 10;
  top: 22px;
  left: 24px;
  display: inline-flex;
  align-items: center;
  min-height: 42px;
  padding: 0 16px;
  border: 1px solid rgba(255,255,255,.82);
  color: #fff;
  background: rgba(0,0,0,.72);
  font: 600 14px/1 system-ui, -apple-system, "Microsoft YaHei", sans-serif;
  letter-spacing: .08em;
  text-decoration: none;
  transition: transform .2s ease, background .2s ease;
}

.back-home:hover,
.back-home:focus-visible {
  background: #000;
  transform: translateY(-2px);
}

.back-home:focus-visible { outline: none; }

.case-study { width: 100%; background: #000; }

.brand-gallery img,
.case-closing img {
  display: block;
  width: 100%;
  height: auto;
}

.brand-gallery img { aspect-ratio: 16 / 9; }

.poster-page {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  align-items: center;
  gap: clamp(18px, 2.2vw, 46px);
  width: 100%;
  min-height: 100vh;
  padding: clamp(42px, 7vw, 132px) clamp(28px, 9vw, 170px);
  background: #000;
}

.poster-page img,
.poster-page video {
  display: block;
  width: 100%;
  max-height: 76vh;
  object-fit: contain;
  background: #000;
}

@media (max-width: 820px) {
  .poster-page { gap: 12px; padding: 26px 16px; }
}