.senior-library-page {
  --senior-ink: var(--library-ink);
  --senior-muted: var(--library-muted);
  --senior-line: var(--library-line);
  --senior-soft: rgba(15, 54, 58, 0.06);
  --senior-accent: var(--library-teal);
  --senior-accent-soft: rgba(15, 107, 104, 0.1);
  --senior-warm: var(--library-amber);
  min-height: 100vh;
  overflow-x: hidden;
}

.senior-library-page a {
  color: inherit;
}

.senior-library-page .sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.senior-library-shell {
  width: min(1180px, calc(100% - 56px));
  margin: 0 auto;
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  align-items: start;
  gap: 12px;
  padding: 8px 0 42px;
}

.senior-library-sidebar {
  min-width: 0;
  border: 1px solid rgba(15, 54, 58, 0.1);
  border-radius: 10px;
  background: rgba(255, 252, 246, 0.76);
}

.senior-library-sidebar-inner {
  position: sticky;
  top: 0;
  min-width: 0;
  padding: 14px;
}

.senior-library-sidebar-label {
  margin: 0 0 12px;
  color: var(--senior-muted);
  font-size: 0.75rem;
  font-weight: 700;
}

.senior-library-chapters {
  display: grid;
  gap: 3px;
}

.senior-library-chapter-group {
  min-width: 0;
}

.senior-library-chapter {
  display: grid;
  grid-template-columns: 18px minmax(0, 1fr) auto;
  align-items: center;
  gap: 6px;
  min-height: 44px;
  padding: 6px 9px 6px 7px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: #3c484b;
  cursor: pointer;
  text-align: left;
  transition: background 140ms ease, color 140ms ease;
}

.senior-library-chapter:hover {
  background: rgba(15, 107, 104, 0.06);
}

.senior-library-chapter.is-active {
  background: var(--senior-accent-soft);
  color: var(--senior-accent);
  font-weight: 700;
}

.senior-library-chapter.is-parent-active {
  background: rgba(15, 107, 104, 0.055);
  color: var(--senior-accent);
  font-weight: 700;
}

.senior-library-chapter-chevron {
  display: grid;
  place-items: center;
  width: 18px;
  height: 28px;
  color: var(--senior-muted);
  font-size: 1rem;
  line-height: 1;
}

.senior-library-chapter-chevron[data-chapter-toggle] {
  border-radius: 4px;
}

.senior-library-chapter-chevron[data-chapter-toggle]:hover {
  background: rgba(15, 107, 104, 0.09);
  color: var(--senior-accent);
}

.senior-library-chapter-chevron.is-empty {
  visibility: hidden;
}

.senior-library-chapter-name {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.senior-library-chapter-count {
  color: var(--senior-muted);
  font-size: 0.78rem;
  font-variant-numeric: tabular-nums;
}

.senior-library-subchapters {
  display: grid;
  gap: 2px;
  margin: 2px 0 6px 24px;
}

.senior-library-subchapter {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 8px;
  min-height: 34px;
  padding: 5px 10px;
  border: 0;
  border-radius: 5px;
  background: transparent;
  color: var(--senior-muted);
  cursor: pointer;
  font: inherit;
  font-size: 0.78rem;
  text-align: left;
}

.senior-library-subchapter:hover {
  background: rgba(15, 107, 104, 0.055);
  color: var(--senior-ink);
}

.senior-library-subchapter.is-active {
  background: var(--senior-accent-soft);
  color: var(--senior-accent);
  font-weight: 700;
}

.senior-library-subchapter span:first-child {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.senior-library-subchapter span:last-child {
  color: var(--senior-muted);
  font-variant-numeric: tabular-nums;
}

.senior-library-content {
  min-width: 0;
  padding: 14px;
  border: 1px solid rgba(15, 54, 58, 0.1);
  border-radius: 10px;
  background: rgba(255, 252, 246, 0.76);
}

.senior-library-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 42px;
  margin-bottom: 14px;
}

.senior-library-heading {
  display: grid;
  grid-template-columns: max-content max-content;
  align-items: baseline;
  gap: 12px;
  min-width: 0;
}

.senior-library-heading h1 {
  margin: 0;
  color: var(--senior-ink);
  font-family: "Songti SC", "Noto Serif SC", "STSong", serif;
  font-size: 1.32rem;
  font-weight: 750;
  letter-spacing: 0;
  white-space: nowrap;
}

.senior-library-heading span {
  color: var(--senior-muted);
  font-size: 0.82rem;
}

.senior-library-filters {
  display: flex;
  align-items: center;
  gap: 8px;
}

.senior-library-filters[hidden],
.senior-library-sections[hidden],
.senior-library-grid[hidden],
.senior-library-pagination[hidden],
.senior-library-worksheet[hidden] {
  display: none !important;
}

.senior-library-filters select {
  height: 34px;
  max-width: 148px;
  padding: 0 30px 0 10px;
  border: 1px solid var(--senior-line);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.58);
  color: var(--senior-ink);
  font: inherit;
  font-size: 0.82rem;
  cursor: pointer;
}

.senior-library-filters select:focus-visible,
.senior-library-chapter:focus-visible,
.senior-library-section:focus-visible,
.senior-library-subchapter:focus-visible,
.senior-library-collection-entry:focus-visible,
.senior-library-page-button:focus-visible,
.senior-library-card:focus-visible,
.senior-worksheet-solution-link:focus-visible {
  outline: 2px solid var(--senior-accent);
  outline-offset: 2px;
}

.senior-library-sections {
  display: flex;
  gap: 4px;
  overflow-x: auto;
  margin: 0 0 20px;
  padding-bottom: 2px;
  scrollbar-width: thin;
}

.senior-library-section {
  flex: 0 0 auto;
  padding: 7px 11px;
  border: 1px solid transparent;
  border-radius: 999px;
  background: transparent;
  color: var(--senior-muted);
  cursor: pointer;
  font-size: 0.82rem;
}

.senior-library-section:hover {
  border-color: rgba(15, 107, 104, 0.24);
  background: rgba(15, 107, 104, 0.06);
  color: var(--senior-ink);
}

.senior-library-section.is-active {
  border-color: rgba(15, 107, 104, 0.36);
  background: rgba(15, 107, 104, 0.1);
  color: var(--senior-accent);
  font-weight: 700;
}

.senior-library-section span {
  margin-left: 6px;
  color: var(--senior-muted);
  font-size: 0.72rem;
}

.senior-library-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.senior-library-collection-entry {
  grid-column: 1 / -1;
  display: flex;
  min-height: 104px;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 18px 20px;
  border: 1px solid var(--senior-line);
  border-radius: 8px;
  background: rgba(15, 107, 104, 0.045);
  transition: border-color 150ms ease, background 150ms ease;
}

.senior-library-collection-entry:hover {
  border-color: rgba(15, 107, 104, 0.3);
  background: rgba(15, 107, 104, 0.075);
}

.senior-library-collection-entry p,
.senior-library-collection-entry h2,
.senior-library-collection-entry span {
  margin: 0;
}

.senior-library-collection-entry p {
  margin-bottom: 4px;
  color: var(--senior-accent);
  font-size: 0.72rem;
  font-weight: 750;
}

.senior-library-collection-entry h2 {
  margin-bottom: 5px;
  color: var(--senior-ink);
  font-family: "Songti SC", "Noto Serif SC", "STSong", serif;
  font-size: 1.05rem;
  letter-spacing: 0;
}

.senior-library-collection-entry div > span {
  color: var(--senior-muted);
  font-size: 0.78rem;
}

.senior-library-collection-action {
  flex: 0 0 auto;
  color: var(--senior-accent);
  font-size: 0.82rem;
  font-weight: 700;
}

.senior-library-card {
  display: grid;
  grid-template-columns: minmax(128px, 36%) minmax(0, 1fr);
  min-height: 184px;
  overflow: hidden;
  border: 1px solid var(--senior-line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.58);
  transition: border-color 150ms ease, background 150ms ease, transform 150ms ease;
}

.senior-library-card:hover {
  transform: translateY(-1px);
  border-color: rgba(15, 107, 104, 0.3);
  background: rgba(255, 255, 255, 0.82);
}

.senior-library-thumbnail {
  min-width: 0;
  background: rgba(248, 244, 235, 0.9);
}

.senior-library-thumbnail img {
  display: block;
  width: 100%;
  height: 100%;
  min-height: 184px;
  object-fit: cover;
}

.senior-library-card-body {
  display: flex;
  min-width: 0;
  flex-direction: column;
  padding: 15px 16px 13px;
}

.senior-library-card-type {
  margin: 0 0 7px;
  color: var(--senior-accent);
  font-size: 0.75rem;
  font-weight: 750;
}

.senior-library-card h2 {
  display: -webkit-box;
  overflow: hidden;
  margin: 0;
  color: var(--senior-ink);
  font-size: 1rem;
  font-weight: 750;
  line-height: 1.5;
  letter-spacing: 0;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
}

.senior-library-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: 10px;
}

.senior-library-tag {
  padding: 3px 7px;
  border-radius: 4px;
  background: var(--senior-soft);
  color: var(--senior-muted);
  font-size: 0.69rem;
}

.senior-library-card-footer {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: end;
  gap: 10px;
  margin-top: auto;
  padding-top: 12px;
}

.senior-library-source,
.senior-library-update {
  color: var(--senior-muted);
  font-size: 0.72rem;
  line-height: 1.45;
}

.senior-library-source {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.senior-library-card-meta {
  display: flex;
  align-items: center;
  gap: 9px;
}

.senior-library-difficulty {
  display: inline-flex;
  gap: 3px;
}

.senior-library-difficulty i {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: rgba(15, 54, 58, 0.14);
}

.senior-library-difficulty i.is-filled {
  background: var(--senior-warm);
}

.senior-library-arrow {
  color: var(--senior-accent);
  font-size: 1rem;
}

.senior-library-empty {
  grid-column: 1 / -1;
  min-height: 260px;
  display: grid;
  place-content: center;
  justify-items: center;
  border-top: 1px solid var(--senior-line);
  color: var(--senior-muted);
  text-align: center;
}

.senior-library-empty h2 {
  margin: 0 0 8px;
  color: var(--senior-ink);
  font-size: 1.05rem;
}

.senior-library-empty p {
  margin: 0;
  font-size: 0.86rem;
}

.senior-library-pagination {
  display: flex;
  justify-content: center;
  gap: 6px;
  margin-top: 26px;
}

.senior-library-worksheet {
  width: min(100%, 780px);
  margin: 0 auto;
}

.senior-library-collection-tabs {
  display: flex;
  width: fit-content;
  margin: 2px auto 22px;
  padding: 3px;
  border: 1px solid var(--senior-line);
  border-radius: 6px;
  background: rgba(15, 54, 58, 0.045);
}

.senior-library-collection-tabs[hidden] {
  display: none;
}

.senior-library-collection-tab {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  min-height: 34px;
  padding: 7px 14px;
  border: 0;
  border-radius: 4px;
  background: transparent;
  color: var(--senior-muted);
  cursor: pointer;
}

.senior-library-collection-tab small {
  font-size: 0.68rem;
}

.senior-library-collection-tab.is-active {
  background: #fff;
  color: var(--senior-accent);
  box-shadow: 0 1px 4px rgba(15, 54, 58, 0.12);
  font-weight: 800;
}

.senior-worksheet-group + .senior-worksheet-group {
  margin-top: 32px;
}

.senior-worksheet-group-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 2px;
  padding: 0 4px 9px;
  border-bottom: 1px solid rgba(15, 54, 58, 0.18);
}

.senior-worksheet-group-heading h2 {
  margin: 0;
  color: var(--senior-ink);
  font-size: 0.88rem;
  font-weight: 800;
  letter-spacing: 0;
}

.senior-worksheet-group-heading span {
  color: var(--senior-muted);
  font-size: 0.72rem;
}

.senior-worksheet-problem {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  gap: 4px;
  padding: 17px 4px 18px;
  border-bottom: 1px solid rgba(15, 54, 58, 0.1);
  color: var(--senior-ink);
}

.senior-worksheet-problem-number {
  padding-top: 1px;
  font-family: "Songti SC", "Noto Serif SC", "STSong", serif;
  font-size: 0.95rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.senior-worksheet-problem-body {
  min-width: 0;
}

.senior-worksheet-line {
  font-family: "Songti SC", "Noto Serif SC", "STSong", serif;
  font-size: 0.94rem;
  line-height: 1.9;
}

.senior-worksheet-line + .senior-worksheet-line {
  margin-top: 4px;
}

.senior-worksheet-options {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  align-items: baseline;
  gap: 6px 14px;
  margin-top: 7px;
  font-family: "Songti SC", "Noto Serif SC", "STSong", serif;
  font-size: 0.94rem;
  line-height: 1.8;
}

.senior-worksheet-options.is-stacked {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 3px;
}

.senior-worksheet-option {
  display: inline-flex;
  align-items: baseline;
  min-width: 0;
}

.senior-worksheet-options:not(.is-stacked) .senior-worksheet-option {
  white-space: nowrap;
}

.senior-worksheet-option-label {
  flex: 0 0 auto;
  margin-right: 5px;
}

.senior-worksheet-source {
  color: var(--senior-muted);
  font-size: 0.84rem;
}

.senior-worksheet-solution-link {
  display: inline-flex;
  align-items: center;
  margin-top: 10px;
  color: var(--senior-accent) !important;
  font-size: 0.78rem;
  font-weight: 700;
}

.senior-worksheet-solution-link:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.senior-worksheet-figures {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 12px 0 6px;
}

.senior-worksheet-figures.is-single {
  grid-template-columns: minmax(0, 1fr);
  width: min(100%, 620px);
  margin-right: auto;
  margin-left: auto;
}

.senior-worksheet-figure {
  min-width: 0;
  margin: 0;
  padding: 10px;
  border: 1px solid rgba(15, 54, 58, 0.12);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.48);
}

.senior-worksheet-figure figcaption {
  margin-bottom: 4px;
  color: var(--senior-muted);
  font-size: 0.7rem;
  font-weight: 700;
}

.senior-worksheet-figure svg {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 720 / 500;
}

.senior-worksheet-figure.is-value-table svg {
  aspect-ratio: 720 / 280;
}

.senior-worksheet-figure p {
  margin: 5px 0 0;
  color: var(--senior-muted);
  font-size: 0.68rem;
}

.senior-library-worksheet .inline-math {
  display: inline;
  vertical-align: baseline;
  white-space: nowrap;
}

.senior-library-worksheet .inline-math sub {
  font-size: 0.72em;
  line-height: 0;
}

.senior-library-worksheet .inline-math sup {
  font-size: 0.72em;
  line-height: 0;
  vertical-align: 0.55em;
}

.senior-library-worksheet .math-fraction {
  display: inline-grid;
  grid-template-rows: auto auto;
  align-items: stretch;
  justify-items: stretch;
  min-width: 1.15em;
  margin: 0 0.08em;
  vertical-align: middle;
  line-height: 1;
  text-align: center;
}

.senior-library-worksheet .math-numerator {
  padding: 0 0.12em 0.06em;
  border-bottom: 1.2px solid currentColor;
}

.senior-library-worksheet .math-denominator {
  padding: 0.05em 0.12em 0;
}

.senior-library-worksheet .math-radical {
  display: inline-flex;
  align-items: flex-start;
  vertical-align: -0.12em;
}

.senior-library-worksheet .math-radical-symbol {
  margin-right: -0.05em;
  font-size: 1.18em;
  line-height: 1;
}

.senior-library-worksheet .math-radicand {
  margin-top: 0.06em;
  padding: 0 0.08em 0 0.1em;
  border-top: 1.2px solid currentColor;
  line-height: 1.05;
}

.senior-library-page-button {
  display: grid;
  place-items: center;
  min-width: 34px;
  height: 34px;
  padding: 0 9px;
  border: 1px solid var(--senior-line);
  border-radius: 5px;
  background: rgba(255, 255, 255, 0.58);
  color: var(--senior-muted);
  cursor: pointer;
}

.senior-library-page-button.is-active {
  border-color: var(--senior-accent);
  background: var(--senior-accent);
  color: #fff;
}

.senior-library-page-button:disabled {
  cursor: default;
  opacity: 0.38;
}

@media (max-width: 1040px) {
  .senior-library-shell {
    width: min(100% - 56px, 1180px);
  }

  .senior-library-shell {
    grid-template-columns: 184px minmax(0, 1fr);
  }

  .senior-library-content {
    padding: 14px;
  }

  .senior-library-card {
    grid-template-columns: 126px minmax(0, 1fr);
  }
}

@media (max-width: 820px) {
  .senior-library-shell {
    grid-template-columns: 1fr;
  }

  .senior-library-sidebar {
    border: 1px solid rgba(15, 54, 58, 0.1);
  }

  .senior-library-sidebar-inner {
    position: static;
    padding: 12px;
  }

  .senior-library-sidebar-label {
    display: none;
  }

  .senior-library-chapters {
    display: flex;
    gap: 5px;
    max-width: 100%;
    overflow-x: auto;
    padding-bottom: 2px;
  }

  .senior-library-chapter-group {
    flex: 0 0 auto;
  }

  .senior-library-chapter {
    flex: 0 0 auto;
    grid-template-columns: 18px auto auto;
    min-height: 36px;
    padding: 5px 10px;
  }

  .senior-library-subchapters {
    margin: 2px 0 0 18px;
  }

  .senior-library-content {
    padding: 14px;
  }
}

@media (max-width: 760px) {
  .senior-library-shell {
    width: min(100% - 28px, 1180px);
    gap: 10px;
    padding: 4px 0 28px;
  }
}

@media (max-width: 720px) {
  .senior-library-toolbar {
    align-items: flex-start;
    flex-direction: column;
    gap: 12px;
  }

  .senior-library-filters {
    width: 100%;
    overflow-x: auto;
  }

  .senior-library-filters label {
    flex: 0 0 auto;
  }

  .senior-library-grid {
    grid-template-columns: 1fr;
  }

  .senior-worksheet-figures {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (max-width: 480px) {
  .senior-library-card {
    grid-template-columns: 112px minmax(0, 1fr);
    min-height: 170px;
  }

  .senior-library-thumbnail img {
    min-height: 170px;
  }

  .senior-library-card-body {
    padding: 12px;
  }

  .senior-library-content {
    padding: 12px;
  }

  .senior-library-collection-entry {
    min-height: 92px;
    padding: 14px;
  }

  .senior-library-collection-action {
    display: none;
  }

  .senior-worksheet-problem {
    grid-template-columns: 25px minmax(0, 1fr);
    padding: 15px 0 16px;
  }

  .senior-worksheet-line {
    font-size: 0.9rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .senior-library-card,
  .senior-library-chapter {
    transition: none;
  }
}