/* Unit-level navigation, separate from the sections inside the current unit. */
.unit-identity {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin: 0 0 1.25rem;
  padding: 1.1rem 1.4rem;
  border: 1px solid var(--teal);
  border-left-width: 5px;
  border-radius: 1rem;
  background: var(--teal-wash);
  font-family: var(--interface-font);
}
.unit-identity > .icon {
  width: 1.7rem;
  height: 1.7rem;
  color: var(--teal-dark);
}
.unit-identity strong {
  display: block;
  color: var(--ink);
  font-size: 1.15rem;
}
.unit-identity p {
  margin: 0.25rem 0 0;
  color: var(--muted);
  font-size: 0.8rem;
}
.unit-identity a {
  margin-left: auto;
  white-space: nowrap;
  font-size: 0.8rem;
}
.unit-context {
  color: var(--teal-dark);
  font-weight: 700;
}
.unit-completion {
  margin: 2rem 0;
  padding: 1.6rem;
  border: 1px solid var(--rule);
  border-radius: 1rem;
  background: var(--teal-wash);
  font-family: var(--interface-font);
}
.unit-completion h2 {
  margin: 0 0 0.75rem;
  font-size: 1.6rem;
}
.unit-completion p {
  margin: 0.6rem 0;
  font-size: 0.85rem;
}
.unit-completion .unit-completion-metrics {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1.5rem;
}
#unit-read-state {
  padding: 0.3rem 0.65rem;
  border: 1px solid var(--rule);
  border-radius: 2rem;
  background: var(--surface);
  font-size: 0.8rem;
}
#unit-read-state[data-read='true'] {
  background: var(--forest);
  color: #fff;
}
.unit-completion-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin-top: 1rem;
}
.unit-completion-actions a {
  font-size: 0.85rem;
}
#unit-progress-status {
  margin: 0.75rem 0 0;
  font-size: 0.8rem;
  color: var(--muted);
}
#unit-progress-error {
  color: var(--warm-ink);
  background: var(--warm-wash);
  padding: 0.8rem;
  border-radius: 0.6rem;
}
.course-navigation {
  position: fixed;
  z-index: 32;
  inset: auto 0 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  gap: 1rem;
  padding: 0.8rem max(1rem, calc((100vw - 1160px) / 2))
    calc(0.8rem + env(safe-area-inset-bottom, 0px));
  border-top: 1px solid var(--rule);
  background: var(--surface);
  box-shadow: 0 -5px 24px #143b2c12;
  font-family: var(--interface-font);
}
.course-navigation a,
.course-navigation button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  min-height: 48px;
  padding: 0.55rem 1rem;
  border: 1px solid var(--rule);
  border-radius: 0.75rem;
  color: var(--teal-dark);
  font-size: 0.85rem;
  font-weight: 600;
  line-height: 1.4;
  text-decoration: none;
}
.course-navigation .course-previous {
  justify-self: start;
}
.course-navigation .course-next {
  justify-self: end;
}
.course-direction-arrow {
  flex: 0 0 auto;
}
.course-direction-copy {
  min-width: 0;
}
.course-label-compact {
  display: none;
}
.course-navigation .course-index {
  background: var(--forest);
  color: #fff;
  border-color: var(--forest);
  font-weight: 750;
}
.course-navigation small {
  display: block;
  font-size: 0.75rem;
  font-weight: 400;
}
.course-navigation button:disabled {
  color: var(--muted);
  background: var(--field);
  opacity: 0.65;
  cursor: default;
}
.reader-page .book-layout {
  padding-bottom: 8rem;
}
.reader-page .contents {
  max-height: calc(100dvh - 14rem - env(safe-area-inset-bottom, 0px));
  overflow-y: auto;
  scroll-padding-bottom: 1rem;
}
.reader-page #selection-toolbar {
  bottom: calc(6.5rem + env(safe-area-inset-bottom, 0px));
}
.reader-page #reader-status {
  bottom: calc(6.5rem + env(safe-area-inset-bottom, 0px));
}
@media (max-width: 650px) {
  .reader-page {
    --course-mobile-bar-height: calc(
      44px + 0.8rem + 1px + env(safe-area-inset-bottom, 0px)
    );
  }
  .unit-identity {
    align-items: flex-start;
    margin-bottom: 1rem;
    padding: 0.8rem 0.9rem;
    gap: 0.6rem;
    border-left-width: 3px;
    border-radius: 0.8rem;
  }
  .unit-identity > .icon {
    flex: 0 0 auto;
    width: 1.25rem;
    height: 1.25rem;
    margin-top: 0.12rem;
  }
  .unit-identity strong {
    font-size: 1rem;
    line-height: 1.35;
  }
  .unit-identity p {
    margin-top: 0.3rem;
    font-size: 0.75rem;
    line-height: 1.5;
  }
  .unit-identity-title {
    font-size: 0.8125rem;
  }
  .unit-identity-description {
    display: none;
  }
  .unit-identity a {
    display: none;
  }
  .unit-completion {
    padding: 1.2rem;
  }
  .course-navigation {
    gap: 0.2rem;
    padding: 0.4rem max(0.5rem, env(safe-area-inset-right, 0px))
      calc(0.4rem + env(safe-area-inset-bottom, 0px))
      max(0.5rem, env(safe-area-inset-left, 0px));
    background: var(--surface);
    border-color: var(--rule);
    box-shadow: 0 -4px 18px #143b2c0a;
  }
  .course-navigation a,
  .course-navigation button {
    min-width: 0;
    min-height: 44px;
    width: 100%;
    padding: 0.4rem 0.25rem;
    border-radius: 0.7rem;
    font-size: 0.8125rem;
    line-height: 1.3;
    gap: 0.15rem;
  }
  .course-navigation .course-index {
    padding-right: 0.4rem;
    padding-left: 0.4rem;
    gap: 0.25rem;
    white-space: nowrap;
  }
  .course-navigation .course-index .icon {
    flex: 0 0 auto;
    width: 0.75rem;
    height: 0.75rem;
  }
  .course-navigation .course-previous,
  .course-navigation .course-next {
    flex-direction: row;
    text-align: center;
    white-space: nowrap;
    border-color: transparent;
    background: transparent;
  }
  .course-navigation .course-direction-arrow {
    font-size: 0.8125rem;
    line-height: 1;
  }
  .course-navigation .course-previous .icon,
  .course-navigation .course-next .icon {
    width: 1rem;
    height: 1rem;
  }
  .course-navigation .course-label-wide,
  .course-navigation .course-target {
    display: none;
  }
  .course-navigation .course-label-compact {
    display: inline;
  }
  .course-navigation .course-end {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 44px;
    color: var(--muted);
    font-size: 0.75rem;
    line-height: 1.3;
    text-align: center;
  }
  .course-navigation button:disabled {
    color: var(--muted);
    background: transparent;
    opacity: 0.75;
  }
  .reader-page .book-layout {
    padding-bottom: calc(var(--course-mobile-bar-height) + 2rem);
  }
  .reader-page #selection-toolbar,
  .reader-page #reader-status {
    bottom: calc(var(--course-mobile-bar-height) + 0.75rem);
  }

  /* The surface stays opaque when blur is unavailable. Only the backdrop,
     never the controls or their labels, receives transparency. */
  @supports (backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px)) {
    .course-navigation {
      background: #fffefbbd;
      -webkit-backdrop-filter: blur(20px) saturate(1.1);
      backdrop-filter: blur(20px) saturate(1.1);
    }
    body[data-theme='sepia'] .course-navigation {
      background: #fbf1dfc7;
    }
    body[data-theme='night'] .course-navigation {
      background: #1d2923d1;
      box-shadow: 0 -4px 18px #00000026;
    }
  }

  @media (prefers-reduced-transparency: reduce) {
    .course-navigation,
    body[data-theme] .course-navigation {
      background: var(--surface);
      -webkit-backdrop-filter: none;
      backdrop-filter: none;
    }
  }
}
@media print {
  .course-navigation,
  .unit-completion-actions,
  #unit-progress-status,
  #unit-progress-error,
  .unit-identity a {
    display: none !important;
  }
  .unit-identity {
    color: #000;
    background: #fff;
    border-color: #999;
  }
  .reader-page .book-layout {
    padding-bottom: 0;
  }
}