/* css/nav.css
 *
 * The persistent bottom navigation: a glassmorphic bar floating ~16px off
 * the bottom edge, four icon+label tiles, and a smooth sliding indicator
 * under the active tab.
 */

.bottom-nav {
  position: absolute;
  left: 50%;
  bottom: var(--space-md);
  transform: translateX(-50%);
  z-index: 50;

  display: flex;
  gap: var(--space-xs);
  padding: 0.5rem;
  width: min(90%, 640px);

  background: var(--color-surface);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border-radius: var(--radius-pill);
  border: 1px solid var(--color-hairline-faint);
  box-shadow: var(--shadow-card);
}

/* A 1px hairline highlight along the top edge, in the accent at low
 * opacity — the glass-card signature used throughout the app. */
.bottom-nav::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(180deg, var(--color-hairline), transparent 40%);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}

.bottom-nav__indicator {
  position: absolute;
  top: 0.5rem;
  bottom: 0.5rem;
  left: 0;
  border-radius: var(--radius-pill);
  background: linear-gradient(180deg, var(--color-accent-faint), transparent);
  border-top: 1px solid var(--color-accent-soft);
  box-shadow: 0 0 24px var(--color-accent-soft);
  transition: transform var(--duration-tab) var(--ease-standard), width var(--duration-tab) var(--ease-standard);
  pointer-events: none;
}

.nav-tab {
  position: relative;
  z-index: 1;
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.2rem;
  padding: 0.6rem 0.25rem;
  border-radius: var(--radius-pill);
  color: var(--color-text-secondary);
  transition: color var(--duration-tab) var(--ease-standard), transform var(--duration-press) var(--ease-standard);
}

.nav-tab__icon svg {
  width: 1.5rem;
  height: 1.5rem;
  display: block;
}

.nav-tab__label {
  font-size: var(--text-caption);
  letter-spacing: 0.01em;
}

.nav-tab.is-active {
  color: var(--color-accent);
}

.nav-tab:active {
  transform: scale(0.97);
}