/* The index bar shared by the books, movies, athletics and photos pages: pill filters, a
   view switch, a rail of section links or year pills, the count, and a way back up. */
html {
  scroll-padding-top: calc(var(--index-bar-height, 60px) + 2rem);
}
.index-bar {
  position: sticky;
  top: 0;
  z-index: 20;
  background: var(--paper);
  border-bottom: 1px solid var(--rule);
  padding-top: 14px;
  margin-bottom: 4px;
}
.index-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 20px;
  align-items: end;
  justify-content: space-between;
}
.index-rail {
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: space-between;
  padding: 10px 0;
  min-height: 46px;
}
.index-count {
  font: 12px var(--sans);
  color: var(--muted);
  margin: 0;
  white-space: nowrap;
}

/* Section links, with a highlight sliding under the one in view. */
.year-rail {
  position: relative;
  display: flex;
  gap: 2px;
  min-width: 0;
  overflow-x: auto;
  scrollbar-width: none;
  font: 12px var(--sans);
}
.year-rail::-webkit-scrollbar {
  display: none;
}
.year-rail a {
  position: relative;
  flex: none;
  padding: 4px 9px;
  border-radius: 999px;
  color: var(--muted);
  text-decoration: none;
  transition: color 150ms ease;
}
.year-rail a:hover {
  color: var(--ink);
}
.year-rail a[aria-current] {
  color: var(--ink);
}
/* White over the paper, differenced: dark where it lies, and whatever year it covers, even
   in passing, turns light. */
.rail-marker {
  position: absolute;
  top: 0;
  left: 0;
  mix-blend-mode: difference;
  pointer-events: none;
}
/* Two round ends and a 1px bar drawn out between them; blended as one, so where they
   overlap they stay a single shape. */
.rail-marker > span {
  position: absolute;
  top: 0;
  left: 0;
  height: var(--marker-size);
  background: #fff;
  transform-origin: 0 0;
  will-change: transform;
}
.rail-marker-cap {
  width: var(--marker-size);
  border-radius: 50%;
}
.rail-marker-bar {
  width: 1px;
}
.year-rail a:focus-visible {
  outline-offset: 0;
}

/* Pills: every choice on show, one pressed. */
.pills {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.pill {
  font: 12px var(--sans);
  color: var(--ink);
  border: 1px solid var(--rule);
  background: transparent;
  border-radius: 999px;
  padding: 6px 12px;
  display: inline-flex;
  gap: 7px;
  align-items: center;
  white-space: nowrap;
}
.pill:hover {
  border-color: var(--muted);
}
.pill[aria-pressed='true'] {
  border-color: var(--ink);
  background: #fff;
}
/* Year pills read like the year links on the shelves: bare until chosen, then filled in. */
.year-rail .pill {
  flex: none;
  border: 0;
  padding: 4px 9px;
  color: var(--muted);
  transition:
    background 150ms ease,
    color 150ms ease;
}
.year-rail .pill:hover {
  color: var(--ink);
}
.year-rail .pill[aria-pressed='true'] {
  background: var(--ink);
  color: var(--paper);
}

/* A view switch: two or three joined buttons, the current one filled in. */
.segmented {
  display: inline-flex;
  border: 1px solid var(--rule);
  border-radius: 999px;
  overflow: hidden;
}
.segmented button {
  font: 12px var(--sans);
  border: 0;
  background: transparent;
  padding: 6px 14px;
}
.segmented button[aria-pressed='true'] {
  background: var(--ink);
  color: var(--paper);
}

.back-to-top {
  position: fixed;
  right: max(20px, env(safe-area-inset-right));
  bottom: max(20px, env(safe-area-inset-bottom));
  z-index: 30;
  width: 44px;
  height: 44px;
  border: 1px solid var(--rule);
  border-radius: 50%;
  background: var(--paper);
  color: var(--ink);
  font: 18px/1 var(--sans);
  box-shadow: 0 4px 14px #3329181a;
}
.back-to-top:hover {
  border-color: var(--ink);
}

/* On phones the filters scroll away and only the rail stays pinned. */
@media (max-width: 600px) {
  .index-bar {
    display: contents;
  }
  .index-controls {
    flex-direction: column;
    align-items: stretch;
    margin: 4px 0 8px;
  }
  .index-rail {
    position: sticky;
    top: 0;
    z-index: 20;
    background: var(--paper);
    border-bottom: 1px solid var(--rule);
    margin-bottom: 4px;
  }
}