.arc-bar {
  position: fixed; left: 50%; bottom: calc(12px + env(safe-area-inset-bottom, 0px)); z-index: 240;
  display: flex; align-items: center; gap: 4px 14px; flex-wrap: wrap; justify-content: center;
  width: max-content; max-width: calc(100vw - 24px); transform: translateX(-50%);
  padding: 8px 8px 8px 18px; border-radius: 999px;
  font-size: 13px; line-height: 1.5; letter-spacing: .04em;
  color: var(--paper, #F6F1E5); background: color-mix(in srgb, var(--sumi, #272F35) 92%, transparent);
  -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px);
  box-shadow: 0 6px 20px rgba(20, 24, 28, .28);
}
.arc-short { display: none; }
body { padding-bottom: calc(76px + env(safe-area-inset-bottom, 0px)); }
.arc-go {
  display: inline-flex; align-items: center; min-height: 44px; padding: 0 16px; border-radius: 999px;
  font-weight: 700; color: var(--sumi, #272F35); background: var(--paper, #F6F1E5); text-decoration: none;
  transition: background-color .15s ease, color .15s ease;
}
.arc-go:hover { background: var(--shu, #C93A21); color: #FFFFFF; }
.arc-go:focus-visible { outline: 3px solid var(--shu, #C93A21); outline-offset: 3px; }
@media (max-width: 480px) {
  .arc-bar { padding: 6px 6px 6px 14px; font-size: 12px; gap: 4px 10px; flex-wrap: nowrap; }
  .arc-long { display: none; }
  .arc-short { display: inline; white-space: nowrap; }
  .arc-go { padding: 0 12px; white-space: nowrap; }
}
@media (prefers-reduced-motion: reduce) { .arc-go { transition: none; } }