.portfolio-back {
  position: fixed;
  z-index: 100;
  top: clamp(56px, 8svh, 76px);
  right: clamp(14px, 4vw, 58px);
  display: inline-grid;
  place-content: center;
  width: 42px;
  height: 42px;
  border: 1px solid #f8f1e8;
  border-radius: 50%;
  background: #161312;
  color: #fff7ed;
  font: 700 20px/1 system-ui, sans-serif;
  text-decoration: none;
}
.portfolio-back:hover { background: #563322; }
.portfolio-back:focus-visible { outline: 2px solid #fff; outline-offset: 3px; }

@media (max-width: 760px), (max-height: 500px) {
  .masthead .portfolio-back, .scene-header .portfolio-back {
    position: static;
    flex: 0 0 44px;
    width: 44px;
    height: 44px;
  }
  .scene-header .portfolio-back { padding: 0; display: grid; background: #161312; }
}