.schoolbook-gallery,
.schoolbook-gallery * {
  box-sizing: border-box;
}

.schoolbook-gallery {
  width: min(100% - 24px, 1000px);
  margin: 28px auto 64px;
  font-family: system-ui, -apple-system,
    BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: #182230;
}

.schoolbook-section {
  margin: 12px 0;
  border: 1px solid #d8dee8;
  border-radius: 12px;
  background: #fff;
  overflow: hidden;
}

.schoolbook-section > summary {
  cursor: pointer;
  list-style: none;
  font-weight: 700;
  padding: 16px 48px 16px 18px;
  position: relative;
  background: #f2f6f8;
  color: #18335f;
}

.schoolbook-section > summary::-webkit-details-marker {
  display: none;
}

.schoolbook-section > summary::after {
  content: "+";
  position: absolute;
  right: 18px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 24px;
}

.schoolbook-section[open] > summary::after {
  content: "−";
}

.schoolbook-section > summary span {
  font-size: 12px;
  background: #fff;
  border-radius: 999px;
  padding: 3px 8px;
  margin-left: 8px;
}

.schoolbook-section-content {
  padding: 14px;
}

.schoolbook-viewer {
  margin: 0 auto;
  min-height: 110px;
  text-align: center;
  border: 1px solid #e1e6ee;
  border-radius: 10px;
  background: #fff;
  padding: 10px;
}

.schoolbook-viewer[hidden] {
  display: none;
}

.schoolbook-viewer img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: auto;
  cursor: zoom-in;
}

.schoolbook-viewer-status {
  font-weight: 700;
  margin: 3px 0 10px;
}

.schoolbook-viewer-nav {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin: 12px 0;
}

.schoolbook-viewer-nav button {
  appearance: none;
  min-width: 120px;
  border: 1px solid #2f69c9;
  border-radius: 8px;
  background: #3498db;
  color: #fff;
  padding: 10px 16px;
  font: 700 14px/1.2 system-ui,
    -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  cursor: pointer;
}

.schoolbook-viewer-nav button:hover {
  background: #2f69c9;
}

.schoolbook-viewer-nav button[hidden] {
  display: none;
}

.schoolbook-page-grid {
  display: grid;
  grid-template-columns:
    repeat(auto-fill, minmax(72px, 1fr));
  gap: 7px;
  align-items: center;
}

.schoolbook-page {
  appearance: none;
  display: block;
  width: 100%;
  min-width: 0;
  margin: 0;
  border: 1px solid #c7d2e5;
  border-radius: 8px;
  background: #fff;
  color: #17345f;
  padding: 9px 6px;
  font: 700 14px/1.2 system-ui,
    -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  text-align: center;
  white-space: nowrap;
  cursor: pointer;
}

.schoolbook-page:hover,
.schoolbook-page.active {
  background: #3498db;
  border-color: #2f69c9;
  color: #fff;
}

.schoolbook-page:focus-visible,
.schoolbook-viewer-nav button:focus-visible {
  outline: 3px solid #f5b642;
  outline-offset: 2px;
}

.schoolbook-lightbox {
  position: fixed;
  inset: 0;
  z-index: 999999;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.6);
  padding: 52px 70px 28px;
  touch-action: pan-y;
}

.schoolbook-lightbox[hidden] {
  display: none;
}

.schoolbook-lightbox-image {
  display: block;
  max-width: 100%;
  max-height: calc(100vh - 90px);
  width: auto;
  height: auto;
  object-fit: contain;
  cursor: pointer;
  user-select: none;
  -webkit-user-drag: none;
}

.schoolbook-lightbox-title {
  position: absolute;
  top: 14px;
  left: 60px;
  right: 60px;
  color: #fff;
  text-align: center;
  font: 600 15px/1.35 system-ui,
    -apple-system, sans-serif;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.schoolbook-lightbox-arrow {
  position: absolute;
  top: 50%;
  width: 50px;
  height: 64px;
  transform: translateY(-50%);
  border: 0;
  border-radius: 999px;
  color: #fff;
  background: rgba(0, 0, 0, 0.42);
  font: 44px/50px system-ui,
    -apple-system, sans-serif;
  cursor: pointer;
}

.schoolbook-lightbox-prev {
  left: 10px;
}

.schoolbook-lightbox-next {
  right: 10px;
}

.schoolbook-lightbox-arrow:disabled {
  opacity: 0.2;
  cursor: default;
}

.schoolbook-lightbox-arrow:not(:disabled):hover {
  background: rgba(52, 152, 219, 0.9);
}

@media (max-width: 600px) {
  .schoolbook-gallery {
    width: min(100% - 14px, 1000px);
    margin-top: 14px;
  }

  .schoolbook-section > summary {
    padding: 13px 42px 13px 13px;
  }

  .schoolbook-section-content {
    padding: 9px;
  }

  .schoolbook-page-grid {
    grid-template-columns:
      repeat(auto-fill, minmax(68px, 1fr));
    gap: 5px;
  }

  .schoolbook-page {
    padding: 8px 4px;
  }

  .schoolbook-viewer-nav button {
    min-width: 105px;
    padding: 9px 12px;
  }

  .schoolbook-lightbox {
    padding: 54px 8px 20px;
  }

  .schoolbook-lightbox-arrow {
    width: 44px;
    height: 58px;
    background: rgba(0, 0, 0, 0.58);
  }

  .schoolbook-lightbox-prev {
    left: 4px;
  }

  .schoolbook-lightbox-next {
    right: 4px;
  }

  .schoolbook-lightbox-title {
    left: 48px;
    right: 48px;
    font-size: 13px;
  }
}