/* --- Bottom tab bar --- */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 68px;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(8px);
  border-top: 1px solid rgba(58, 42, 26, 0.08);
  box-shadow: 0 -4px 16px rgba(58, 42, 26, 0.08);
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  z-index: 200;
  transition: transform 0.3s ease;
}
.bottom-nav--hidden {
  transform: translateY(110%);
  pointer-events: none;
}
.bottom-nav__tab {
  background: none;
  border: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  cursor: pointer;
  color: var(--fg-soft);
  padding: 6px 0;
  transition: color 0.2s, transform 0.15s;
}
.bottom-nav__tab:active { transform: scale(0.95); }
.bottom-nav__icon { font-size: 24px; line-height: 1; }
.bottom-nav__label { font-size: 11px; font-weight: 600; }
.bottom-nav__tab--active {
  color: var(--accent);
}
.bottom-nav__tab--active .bottom-nav__icon {
  transform: scale(1.15);
  filter: drop-shadow(0 2px 4px rgba(255, 138, 76, 0.35));
}

/* 主內容下方留 tab bar 空間 */
#app {
  padding-bottom: 80px;
}

/* --- Home CTA (首頁主按鈕) --- */
.big-card--cta {
  background: linear-gradient(135deg, var(--accent), #ffab70);
  color: var(--accent-fg, #fff);
  border: none;
  box-shadow: 0 6px 18px rgba(255, 138, 76, 0.35);
}
.big-card--cta .big-card__title { color: #fff; }
.big-card--cta .big-card__subtitle { color: rgba(255, 255, 255, 0.85); }

/* --- Learn tab "all done" --- */
.learn-done {
  background: rgba(255, 255, 255, 0.6);
  border: 2px dashed rgba(255, 138, 76, 0.4);
  border-radius: var(--radius-card);
  padding: 32px 20px;
  text-align: center;
}
.learn-done__icon { font-size: 56px; margin-bottom: 12px; }
.learn-done__title { font-size: 22px; font-weight: 800; color: var(--fg); margin-bottom: 6px; }
.learn-done__subtitle { font-size: 14px; color: var(--fg-soft); }