/* ================================================
   common.css — shared, theme-neutral page chrome
   Linked by every page before its own style.css.

   Theme hooks (set in each page's :root):
     --back-color       back-link text colour
     --back-hover       back-link hover colour (page accent)
     --scrollbar-thumb  scrollbar thumb colour

   Optional, for pages whose content sits in a centred
   column (so the back-link lines up with that column):
     --back-nav-width      column max-width (default: none)
     --back-nav-gutter     column side padding (default 28px)
     --back-nav-gutter-sm  side padding at <=600px (default 20px)
   ================================================ */

/* ── Back nav ───────────────────────────────────────────── */
.back-nav
{
  position: relative;
  z-index: 1;
  box-sizing: border-box;
  max-width: var(--back-nav-width, none);
  margin: 0 auto;
  padding: 28px var(--back-nav-gutter, 28px) 0;
  line-height: 1.5;
  opacity: 0;
  animation: fadeUp 0.4s ease forwards;
  animation-delay: 0.02s;
}

.back-link
{
  font-family: 'DM Mono', monospace;
  font-size: 0.688rem;
  color: var(--back-color, #7a7568);
  text-decoration: none;
  letter-spacing: 0.06em;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: color 0.2s;
}

.back-link:hover,
.back-link:focus-visible
{
  color: var(--back-hover, currentColor);
}

@media (max-width: 600px)
{
  .back-nav { padding: 20px var(--back-nav-gutter-sm, 20px) 0; }
}

/* ── Entrance animation ─────────────────────────────────── */
@keyframes fadeUp
{
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}

@media (prefers-reduced-motion: reduce)
{
  .back-nav { animation: none; opacity: 1; }
}

/* ── Scrollbar ──────────────────────────────────────────── */
::-webkit-scrollbar       { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb, rgba(0,0,0,0.15)); border-radius: 3px; }