.viewer-nav {
  position: fixed;
  left: 50%;
  bottom: var(--edge);
  translate: -50% 0;
  display: flex;
  align-items: center;
  padding: var(--nav-gap);
  border: var(--nav-border) solid var(--nav-edge);
  border-radius: var(--nav-outer);
  background: var(--background-tint);
  -webkit-backdrop-filter: var(--effect-style-background-blur-veil);
  backdrop-filter: var(--effect-style-background-blur-veil);
  box-shadow: var(--effect-style-drop-shadow-float);
}

.viewer-step {
  display: flex;
  align-items: center;
  justify-content: center;
  height: var(--nav-h);
  padding: 0 var(--padding-control);
  border: 0;
  border-radius: var(--nav-inner);
  background: transparent;
  color: var(--nav-ink-on);
  cursor: pointer;
  -webkit-user-select: none;
  user-select: none;
  transition:
    background-color 200ms ease,
    color 200ms ease,
    scale 200ms cubic-bezier(0.32, 0.72, 0, 1);
}

@media (hover: hover) {
  .viewer-step:hover:not([aria-disabled="true"]) { background: var(--background-overlay2); }
}

body[data-cursor="on"] .viewer-step:hover { background: transparent; }

.viewer-step:active:not([aria-disabled="true"]) {
  scale: 0.94;
  transition-duration: 200ms, 200ms, 90ms;
}

.viewer-step[aria-disabled="true"] {
  color: var(--content-disabled);
  cursor: default;
}

.viewer-step:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.viewer-step svg { width: var(--icon-medium); height: var(--icon-medium); }

@media (prefers-reduced-motion: reduce) {
  .viewer-step { transition: none; }
}