/* ==========================================================================
   Page chrome — sticky top bar and footer.
   ========================================================================== */

/* --------------------------------------------------------------------------
   Top bar
   -------------------------------------------------------------------------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--rule);
  padding: 22px 0;
  background: transparent;
  transition: padding 0.28s ease, background 0.28s ease, border-color 0.28s ease,
    box-shadow 0.28s ease;
}

/* Scrolled state: a thin sheet of frosted paper, not a solid block */
.topbar.is-stuck {
  padding: 11px 0;
  background: var(--bar-bg);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  backdrop-filter: saturate(180%) blur(14px);
  border-bottom-color: transparent;
  box-shadow: 0 1px 0 var(--rule), 0 8px 24px -18px var(--bar-shadow);
}

/* No blur support (older Firefox): fall back to near-opaque paper */
@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
  .topbar.is-stuck {
    background: var(--paper);
  }
}

.topbar-inner {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 24px;
}

.topbar .left {
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 12px;
  letter-spacing: 0.06em;
  transition: opacity 0.28s ease;
}

.topbar .right {
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 12px;
  letter-spacing: 0.06em;
  text-align: right;
  color: var(--muted);
}

.topbar.is-stuck .left {
  opacity: 0.55;
}

.monogram-link {
  text-decoration: none;
  color: inherit;
}

.monogram {
  font-family: var(--font-sans);
  font-weight: 400;
  font-style: normal;
  font-size: 22px;
  line-height: 1;
  letter-spacing: -0.01em;
  transition: font-size 0.28s ease;
}

.topbar.is-stuck .monogram {
  font-size: 18px;
}

.monogram .dot {
  color: var(--accent);
}

.theme-toggle {
  background: none;
  border: 1px solid var(--rule);
  padding: 6px 14px;
  font-family: var(--font-sans);
  font-size: 12px;
  color: var(--ink);
  cursor: pointer;
  letter-spacing: 0.04em;
  transition: border-color 0.3s ease, color 0.3s ease;
}

.theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

@media (prefers-reduced-motion: reduce) {
  .topbar,
  .topbar .left,
  .monogram {
    transition: none;
  }
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */

footer {
  padding: 60px var(--gutter) 80px;
  display: grid;
  grid-template-columns: 1.2fr 1fr 0.8fr;
  gap: 40px;
  align-items: center;
  max-width: var(--max);
  margin: 0 auto;
  border-top: 1px solid var(--rule);
}

.back-to-top {
  background: none;
  border: none;
  padding: 0;
  text-align: left;
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 14px;
  color: var(--ink);
  cursor: pointer;
  transition: color 0.24s ease;
}

.back-to-top:hover {
  color: var(--accent);
}

.footer-cta {
  text-align: center;
}

.footer-cta button {
  color: var(--paper);
  background: var(--accent);
  padding: 10px 20px;
  border: none;
  border-radius: 4px;
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.24s ease;
}

.footer-cta button:hover {
  background: color-mix(in srgb, var(--accent) 85%, var(--ink));
}

.footer-meta {
  text-align: right;
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 12px;
  letter-spacing: 0.02em;
  color: var(--muted);
}

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */

@media (max-width: 800px) {
  footer {
    grid-template-columns: 1fr;
    text-align: center;
    padding: 40px var(--gutter-sm) 60px;
    gap: 20px;
  }

  .back-to-top,
  .footer-cta,
  .footer-meta {
    text-align: center;
  }

  /* Comfortable thumb targets for the two controls that are pure text */
  .back-to-top {
    padding: 10px 0;
  }

  .theme-toggle {
    padding: 9px 14px;
  }
}