/* A single refractive surface, with the controls above it as siblings. */
.app { padding-bottom: calc(92px + env(safe-area-inset-bottom, 0px)); }
.bottom-nav {
  position: fixed; z-index: 20; left: 50%;
  bottom: 0;
  transform: translateX(-50%); width: min(100%, 520px);
  height: calc(56px + env(safe-area-inset-bottom, 0px)); display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  align-items: stretch; padding: 2px 8px calc(2px + env(safe-area-inset-bottom, 0px)); isolation: isolate;
}
.bottom-glass {
  position: absolute; inset: 0; border-radius: 0;
  background: rgba(249, 246, 237, .34);
  border-top: 1px solid rgba(255,255,255,.5);
  box-shadow: 0 -1px 6px rgba(83,61,45,.035), inset 0 1px 0 rgba(255,255,255,.3);
  -webkit-backdrop-filter: blur(2.2px) saturate(1.05);
  backdrop-filter: blur(2.2px) saturate(1.05);
  pointer-events: none;
}
.bottom-nav button {
  position: relative; z-index: 1; border: 0; border-radius: 20px;
  background: transparent; color: #9b8b7e; padding: 3px 1px;
  display: flex; align-items: center; justify-content: center; flex-direction: column;
  gap: 1px; min-width: 0; min-height: 48px; font-size: 12px; line-height: 1.1;
  transition: color .2s ease, background-color .2s ease, transform .2s ease;
}
.bottom-nav button[aria-current="page"] { color: #513529; background: rgba(255,255,255,.14); }
.bottom-nav button:active { transform: scale(.95); }
.bottom-nav svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; }
@media (prefers-reduced-motion: reduce) { .bottom-nav button { transition: none; } }