/* The Folio application frame: the settings rail and the viewer stage, whose
   slots stay blank when the settings dialog is the subject. */
.fo-nav,
.fo-nav-group {
  display: grid;
  gap: var(--mk-space-1);
  min-width: 0;
}
.fo-nav-group {
  gap: var(--mk-space-2);
}
.fo-nav-group > .fo-group-label {
  padding: 0 var(--mk-space-2);
}
.fo-nav-item {
  display: flex;
  align-items: center;
  gap: var(--mk-space-2);
  min-height: 32px;
  min-width: 0;
  padding: var(--mk-space-1) var(--mk-space-2);
  border: 1px solid transparent;
  border-radius: var(--mk-radius-chrome);
  color: var(--mk-color-text-muted);
  text-decoration: none;
  transition:
    background var(--mk-motion-fast) var(--mk-motion-easing),
    color var(--mk-motion-fast) var(--mk-motion-easing);
}
.fo-nav-item:hover {
  background: color-mix(in srgb, var(--mk-color-accent) 9%, transparent);
  color: var(--mk-color-text);
}
.fo-nav-icon {
  display: inline-flex;
  color: var(--mk-color-text-muted);
}
.fo-nav-label {
  font-size: var(--mk-type-ui-size);
  line-height: var(--mk-type-ui-line);
  font-weight: var(--mk-font-medium);
  overflow-wrap: anywhere;
}
.fo-nav-item[aria-current] {
  background: var(--mk-color-surface);
  border-color: var(--mk-color-border);
  box-shadow: var(--mk-shadow-small);
  color: var(--mk-color-text);
}
.fo-nav-item[aria-current] .fo-nav-label {
  font-weight: var(--mk-font-semibold);
}
.fo-nav-item[aria-current] .fo-nav-icon {
  color: var(--mk-color-text);
}
.fo-stage {
  display: flex;
  flex-direction: column;
}
.fo-stage-bar {
  display: flex;
  align-items: center;
  gap: var(--mk-space-4);
  flex-shrink: 0;
  min-height: var(--mk-layout-topbar);
  padding: 0 var(--mk-space-4);
  border-bottom: 1px solid var(--mk-color-border);
}
.fo-stage-slot {
  height: 28px;
}
.fo-stage-slot-lead {
  width: 220px;
}
.fo-stage-slot-middle {
  flex: 1;
  min-width: 0;
}
.fo-stage-slot-trail {
  width: 160px;
}
.fo-stage-canvas {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-height: 0;
  background: var(--mk-color-surface);
}