/* System — scroll-spy, section rail, view transitions, magnetics, scramble */

/* —— Nav scroll-spy + FLIP underline —— */
.site-nav__list {
  position: relative;
}

.site-nav__link.is-current {
  color: var(--accent);
}

.site-nav__underline {
  position: absolute;
  bottom: 2px;
  left: 0;
  height: 1.5px;
  width: 0;
  border-radius: 1px;
  background: var(--accent);
  transform-origin: left center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 200ms var(--ease-out);
}

.site-nav__underline.is-visible {
  opacity: 1;
}

@media (max-width: 768px) {
  .site-nav__underline {
    display: none;
  }
}

/* —— Right-edge section rail —— */
.rail {
  position: fixed;
  top: 50%;
  right: clamp(0.75rem, 2vw, 1.75rem);
  z-index: 70;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: var(--space-3);
  transform: translateY(-50%);
}

.rail__dot {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  width: 1.5rem;
  height: 1rem;
  padding: 0;
  border: 0;
  background: none;
  cursor: pointer;
}

.rail__dot::after {
  content: "";
  width: 5px;
  height: 5px;
  border-radius: 3px;
  background: var(--ink-muted);
  opacity: 0.45;
  transition:
    width 260ms var(--ease-spring),
    height 200ms var(--ease-out),
    background-color 200ms var(--ease-out),
    opacity 200ms var(--ease-out);
}

.rail__dot:hover::after,
.rail__dot:focus-visible::after {
  opacity: 1;
  background: var(--ink);
}

.rail__dot.is-current::after {
  width: 16px;
  opacity: 1;
  background: var(--accent);
}

.rail__dot:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  border-radius: var(--radius-sm);
}

.rail__label {
  position: absolute;
  right: calc(100% + 0.5rem);
  padding: 0.15rem 0.4rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.58rem;
  letter-spacing: 0.12em;
  white-space: nowrap;
  opacity: 0;
  transform: translateX(4px);
  pointer-events: none;
  transition:
    opacity 180ms var(--ease-out),
    transform 220ms var(--ease-out);
}

.rail__dot:hover .rail__label,
.rail__dot:focus-visible .rail__label {
  opacity: 1;
  transform: translateX(0);
}

@media (max-width: 1000px) {
  .rail {
    display: none;
  }
}

body.palette-open .rail,
body.terminal-open .rail,
body.nav-open .rail {
  display: none;
}

/* —— Magnetic primary buttons —— */
.btn {
  transform: translate(var(--mx, 0px), var(--my, 0px)) scale(var(--press, 1));
}

.btn:active {
  --press: 0.98;
}

.btn.is-magnet {
  transition:
    color 180ms var(--ease-out),
    background-color 180ms var(--ease-out),
    border-color 180ms var(--ease-out),
    transform 110ms linear;
}

@media (prefers-reduced-motion: reduce), (hover: none) {
  .btn {
    --mx: 0px;
    --my: 0px;
  }
}

/* —— View Transitions for the theme swap —— */
@media (prefers-reduced-motion: no-preference) {
  ::view-transition-old(root),
  ::view-transition-new(root) {
    animation-duration: 320ms;
    animation-timing-function: cubic-bezier(0.22, 1, 0.36, 1);
  }
}

@media (prefers-reduced-motion: reduce) {
  ::view-transition-old(root),
  ::view-transition-new(root) {
    animation: none;
  }
}

/* The scope canvases repaint on the next frame; freeze them during the fade. */
.is-theme-transition .scope__trace {
  opacity: 0.999;
}

/* —— Scroll-driven reveals, with the IntersectionObserver path as fallback —— */
@keyframes reveal-in {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@supports (animation-timeline: view()) {
  @media (prefers-reduced-motion: no-preference) {
    .has-scroll-reveal [data-reveal] {
      opacity: 1;
      transform: none;
      transition: none;
      animation: reveal-in linear both;
      animation-timeline: view();
      animation-range: entry 8% cover 24%;
    }
  }
}

/* —— Section heading scramble —— */
.section__label > span[aria-hidden="true"] {
  display: inline-block;
  min-width: 1ch;
}

/* —— Perf HUD (palette-only) —— */
.perf-hud {
  position: fixed;
  left: var(--space-5);
  bottom: var(--space-5);
  z-index: 80;
  margin: 0;
  padding: 0.3rem 0.5rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  color: var(--ok);
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.08em;
  font-variant-numeric: tabular-nums;
  pointer-events: none;
}

.perf-hud[hidden] {
  display: none;
}

/* —— Konami scope mode —— */
.scope-mode {
  position: fixed;
  inset: 0;
  z-index: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.scope-mode[hidden] {
  display: none;
}

html.is-scope-mode {
  --accent: #3adf7c;
  --accent-dim: #1f7a45;
}

html.is-scope-mode body::before {
  opacity: 0.25;
}

html.is-scope-mode .site {
  position: relative;
  z-index: 1;
}

@media print {
  .scope-mode {
    display: none !important;
  }
}