/* REVEAL ON SCROLL MOTORS (Mechanic A) - Preserves X/Y offsets, transitions from above */
.reveal-item {
  opacity: 0;
  --anim-y: -20px; /* Start 20px above final offset position */
  transform: translate(var(--base-x, 0px), calc(var(--base-y, 0px) + var(--anim-y)));
  transition: opacity var(--reveal-dur, 1s) cubic-bezier(0.25, 1, 0.5, 1), 
              transform var(--reveal-dur, 1s) cubic-bezier(0.25, 1, 0.5, 1);
}

.reveal-item.is-visible {
  opacity: 1;
  --anim-y: 0px; /* Slides down to its configured offset position */
}

/* SOLID FADE FOR FOOTER (Eliminates layout oscillation flickering at page boundaries) */
#site-footer.reveal-item {
  transform: none !important; /* Forces static placement to prevent IntersectionObserver oscillation */
  opacity: 0;
  transition: opacity var(--reveal-dur, 1s) ease-out;
}
#site-footer.reveal-item.is-visible {
  opacity: 1;
}

/* KEN BURNS ANIMATION (Mechanic F) */
.s1-bg-active {
  animation: kenBurnsS1 var(--s1-kb-dur) ease-in-out infinite alternate;
}

@keyframes kenBurnsS1 {
  0% { transform: scale(var(--s1-kb-start)); }
  100% { transform: scale(var(--s1-kb-end)); }
}

.s5-bg-active {
  animation: kenBurnsS5 var(--s5-kb-dur) ease-in-out infinite alternate;
}

@keyframes kenBurnsS5 {
  0% { transform: scale(var(--s5-kb-start)); }
  100% { transform: scale(var(--s5-kb-end)); }
}

/* BOUNCING ANCHOR ARROWS (Mechanic H) */
.arrow-bounce {
  animation: arrowBounceAnim var(--bounce-duration, 1.5s) infinite ease-in-out;
}

@keyframes arrowBounceAnim {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(var(--bounce-distance, 8px)); }
}

/* DYNAMIC HOVER UNDERLINES (Mechanic G) */
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 100%;
  height: 1px;
  background-color: var(--underline-color, #FFFFFF);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--underline-duration, 0.3s) ease;
}

.nav-link:hover::after {
  transform: scaleX(1);
}

/* ACCESSIBILITY FALLBACK: PREFERS-REDUCED-MOTION (Rule 7) */
@media (prefers-reduced-motion: reduce) {
  .s1-bg-active, .s5-bg-active {
    animation: none !important;
    transform: scale(1) !important;
  }
  .arrow-bounce {
    animation: none !important;
  }
  .reveal-item {
    opacity: 1 !important;
    transform: translate(var(--base-x, 0px), var(--base-y, 0px)) !important;
    transition: none !important;
  }
  .transition-all, .transition-transform, .transition-opacity {
    transition: none !important;
  }
}