/* ============================================================
   LAYOUT — page structure, containers, animations
   ============================================================ */

.page-body { background-color: var(--bg); }

section {
  max-width: var(--container);
  margin: 0 auto;
  padding: 100px 24px;
  scroll-margin-top: var(--nav-h);
}

/* Section heading underline */
section > h2 {
  position: relative;
  display: inline-block;
  margin-bottom: 40px;
  padding-bottom: 10px;
}
section > h2::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 56px;
  height: 3px;
  background: var(--accent);
  border-radius: 2px;
}

/* Fade animations */
.fade-up {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}
.fade-up.show {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  html { scroll-behavior: auto; }
}

/* Back-to-top */
#backToTop {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 46px;
  height: 46px;
  font-size: 1.25rem;
  background-color: var(--dark);
  color: var(--on-dark);
  border-radius: 50%;
  display: none;
  align-items: center;
  justify-content: center;
  line-height: 1;
  padding: 0;
  z-index: 900;
  box-shadow: var(--shadow);
  transition: background-color 0.3s, transform 0.3s;
}
#backToTop:hover { background-color: var(--accent); color: var(--accent-ink); transform: translateY(-3px); }