.site-header {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
}

.site-header .back {
  justify-self: start;
  color: #f2d579;
  text-decoration: none;
  font-size: 14px;
  font-weight: 700;
}

.site-header .back:hover,
.site-header .back:focus-visible { color: #fff0aa; }
.site-header .brand { justify-self: center; }
.site-header .header-spacer { width: 100%; }

@media (max-width: 680px) {
  .site-header { grid-template-columns: 1fr auto; }
  .site-header .header-spacer { display: none; }
  .site-header .back { font-size: 0; }
  .site-header .back::before { content: "←"; font-size: 20px; }
}