:root {
    --bg: #f5f8fd;
    --ink: #06133f;
    --muted: #64718f;
    --line: #dce5f2;
    --blue: #155bdc;
    --blue-soft: #eaf2ff;
    --green: #21a657;
    --purple: #7a55d9;
    --shadow: 0 12px 32px rgba(15, 34, 74, .10);
    font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: var(--ink);
    background: var(--bg);
}

a { color: inherit; text-decoration: none; }
button, input, textarea { font: inherit; }

/* FocusOnNavigate focuses route headings for screen readers; the heading itself is not interactive. */
h1[tabindex="-1"]:focus {
    outline: none;
}

button,
.btn {
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 15px;
    font-weight: 600;
    line-height: 1.2;
    letter-spacing: 0;
}

.loading-shell,
.boot-loader {
    min-height: 100vh;
    display: grid;
    place-items: center;
    padding: 24px;
    color: var(--blue);
    background:
        radial-gradient(circle at 50% 42%, rgba(21, 91, 220, .10), transparent 34%),
        var(--bg);
}

.loading-card,
.boot-loader-card {
    width: min(340px, 100%);
    display: grid;
    gap: 14px;
}

.loading-title {
    color: var(--blue);
    font-size: 1.5rem;
    font-weight: 900;
    letter-spacing: .01em;
    text-align: center;
}

.loading-progress {
    width: 100%;
    height: 8px;
    overflow: hidden;
    border-radius: 999px;
    background: #dce8fb;
    box-shadow: inset 0 0 0 1px rgba(21, 91, 220, .08);
}

.loading-progress-bar {
    width: var(--blazor-load-percentage, 8%);
    min-width: 8%;
    height: 100%;
    border-radius: inherit;
    background: linear-gradient(90deg, #21a657, #155bdc);
    transition: width .18s ease;
}

.loading-progress-bar.is-indeterminate {
    width: 42%;
    min-width: 42%;
    animation: loading-progress-slide 1.1s ease-in-out infinite;
}

.loading-progress-text {
    min-height: 1rem;
    color: var(--muted);
    font-size: .82rem;
    font-weight: 700;
    text-align: center;
}

.loading-progress-text::after {
    content: var(--blazor-load-percentage-text, "Загрузка...");
}

@keyframes loading-progress-slide {
    0% { transform: translateX(-110%); }
    100% { transform: translateX(240%); }
}

.app-shell {
    min-height: 100vh;
    display: flex;
}

.mobile-drawer {
    position: sticky;
    top: 0;
    width: 220px;
    min-width: 220px;
    height: 100vh;
}

.mobile-drawer-backdrop,
.mobile-drawer-close,
.mobile-menu-button { display: none; }

.sidebar {
    width: 100%;
    height: 100vh;
    padding: 24px 18px;
    background: rgba(255, 255, 255, .94);
    border-right: 1px solid var(--line);
    overflow-y: auto;
}

.sidebar-brand, .brand-inline, .admin-login-logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-mark {
    width: 38px;
    height: 30px;
    display: grid;
    place-items: center;
    border-radius: 8px;
    color: white;
    background: linear-gradient(145deg, #155bdc, #3a91ff);
    font-weight: 900;
}

.logo-copy strong {
    display: block;
    color: var(--blue);
    font-size: 1.2rem;
    line-height: 1;
}

.logo-copy small {
    display: block;
    max-width: 170px;
    margin-top: 4px;
    color: var(--ink);
    font-size: .67rem;
    line-height: 1.25;
}

.sidebar-nav {
    margin-top: 26px;
    display: grid;
    gap: 18px;
}

.sidebar-nav a, .nav-home {
    display: flex;
    align-items: center;
    gap: 8px;
    min-height: 32px;
    padding: 8px 10px;
    border-radius: 8px;
    color: #12204b;
    font-weight: 600;
    font-size: .9rem;
}

.sidebar-nav a.active {
    color: var(--blue);
    background: var(--blue-soft);
}

.grade-group, .grade-links {
    display: grid;
    gap: 2px;
}

.grade-group-header {
    display: flex;
    align-items: center;
    width: 100%;
    gap: 8px;
    margin: 0 0 4px;
    padding: 2px 0;
    border: 0;
    border-radius: 6px;
    background: transparent;
    color: #12204b;
    cursor: pointer;
    font: inherit;
    text-align: left;
}

.grade-group-link {
    display: flex;
    align-items: center;
    gap: 8px;
    flex: 1;
    min-width: 0;
    min-height: 28px;
    font-weight: 800;
}

.grade-group-header:focus-visible {
    outline: 2px solid rgba(30, 99, 230, .35);
    outline-offset: 3px;
}

.grade-group-toggle,
.nav-icon,
.link-chevron { display: none; }

.grade-links[hidden] {
    display: none;
}

.group-icon { color: var(--green); font-size: .8rem; }
.side-muted, .copyright { color: var(--muted); font-size: .85rem; }

.app-main {
    flex: 1;
    min-width: 0;
}

.topbar {
    position: sticky;
    top: 0;
    z-index: 2;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 76px;
    padding: 16px 40px;
    background: rgba(245, 248, 253, .86);
    backdrop-filter: blur(12px);
}

.topbar-search-disabled { display: none; }

.brand-inline { display: none; }

.search-box {
    position: relative;
    width: min(520px, 100%);
}

.search-box input {
    width: 100%;
    height: 44px;
    padding: 0 42px 0 48px;
    border: 1px solid var(--line);
    border-radius: 24px;
    background: white;
    color: var(--ink);
    outline: none;
}

.search-icon {
    position: absolute;
    left: 18px;
    top: 10px;
    color: var(--blue);
    font-size: 1.2rem;
}

.search-results {
    position: absolute;
    top: 64px;
    width: min(520px, calc(100% - 80px));
    display: grid;
    gap: 4px;
    padding: 8px;
    background: white;
    border: 1px solid var(--line);
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.search-results button {
    border: 0;
    padding: 10px 12px;
    text-align: left;
    color: var(--ink);
    background: transparent;
    border-radius: 6px;
    cursor: pointer;
}

.search-results button:hover { background: var(--blue-soft); }

.content-shell {
    width: min(1180px, 100%);
    padding: 10px 40px 56px;
}

main.content-shell:has(.admin-books-header) {
    width: 100%;
    padding-inline: 16px;
}

/* /works/create needs the full app-main width for the 1368px builder grid while preserving the sidebar boundary. */
main.content-shell:has(.worksheet-builder-shell) {
    width: 100%;
}

main.content-shell:has(.rounding-generator-layout) { width: 100%; }
.generator-layout.rounding-generator-layout { grid-template-columns: 360px minmax(0, 1fr); }
.rounding-generator-layout > .generator-form { align-self: start; }
.rounding-generator-layout > .preview-card { padding: 0; min-width: 0; align-self: start; overflow: hidden; }
.rounding-generator-layout > .preview-card > h2,
.rounding-generator-layout > .preview-card > .empty-state { margin: 28px; }

@font-face {
    font-family: "Worksheet Noto Sans";
    src: url("../fonts/NotoSans-Regular.ttf") format("truetype");
    font-style: normal;
    font-weight: 400;
    font-display: block;
}

.admin-login-shell {
    width: 100%;
    min-height: 100vh;
    padding: 0;
}

.hero-panel {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 330px;
    gap: 28px;
    min-height: 300px;
    padding: 48px 56px;
    align-items: center;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: linear-gradient(135deg, #f4f9ff, #eaf4ff);
    box-shadow: var(--shadow);
}

.hero-panel h1 {
    max-width: 560px;
    margin: 0 0 18px;
    font-size: 2.35rem;
    line-height: 1.05;
}

.hero-panel p, .page-heading p, .admin-toolbar p {
    color: var(--muted);
    line-height: 1.6;
}

.hero-art {
    position: relative;
    min-height: 210px;
}

.book-stack span {
    position: absolute;
    right: 20px;
    width: 190px;
    height: 52px;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.book-stack span:nth-child(1) { top: 28px; background: #3a91ff; transform: rotate(8deg); }
.book-stack span:nth-child(2) { top: 74px; background: #ff895a; transform: rotate(-3deg); }
.book-stack span:nth-child(3) { top: 116px; background: #29b66f; transform: rotate(5deg); }

.math-card {
    position: absolute;
    left: 18px;
    bottom: 24px;
    padding: 24px 28px;
    border-radius: 8px;
    color: #1b3776;
    background: white;
    font-size: 1.6rem;
    font-weight: 800;
    box-shadow: var(--shadow);
    transform: rotate(10deg);
}

.stage-grid, .grade-card-grid, .subject-grid, .section-grid, .popular-grid, .admin-nav-grid, .admin-page {
    display: grid;
    gap: 22px;
}

.stage-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    margin: -48px 56px 42px;
    position: relative;
    z-index: 1;
}

.stage-card, .grade-card, .popular-card, .subject-card, .section-card, .admin-nav-grid a, .admin-panel, .preview-card, .generator-form, .material-card, .page-section, .worksheet-builder-toolbar {
    border: 1px solid var(--line);
    border-radius: 8px;
    background: white;
    box-shadow: var(--shadow);
}

.stage-card {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 4px 16px;
    padding: 22px;
    align-items: center;
}

.stage-badge {
    grid-row: span 2;
    display: grid;
    place-items: center;
    width: 54px;
    height: 54px;
    border-radius: 8px;
    color: white;
    background: linear-gradient(145deg, var(--green), #5bd785);
    font-weight: 900;
}

.stage-card:nth-child(2) .stage-badge { background: linear-gradient(145deg, var(--blue), #58a1ff); }
.stage-card:nth-child(3) .stage-badge { background: linear-gradient(145deg, var(--purple), #9f7bff); }

.grade-card-grid {
    grid-template-columns: repeat(4, minmax(190px, 1fr));
}

.grade-card {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 16px;
    padding: 22px;
    align-items: center;
}

.grade-card-badge {
    display: grid;
    place-items: center;
    width: 48px;
    height: 48px;
    border-radius: 8px;
    color: white;
    background: linear-gradient(145deg, var(--blue), #58a1ff);
    font-weight: 900;
}

.grade-card h2 {
    margin: 0 0 6px;
    font-size: 1.1rem;
}

.grade-card p {
    margin: 0;
    color: var(--muted);
    line-height: 1.5;
}

.page-section, .page-heading {
    margin-top: 26px;
}

.page-section, .generator-form, .preview-card {
    padding: 28px;
}

.page-section.compact {
    max-width: 640px;
}

.page-heading h1, .admin-page h1 {
    margin: 0 0 8px;
    font-size: 2rem;
}

.page-heading-row {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 18px;
}

.page-heading-row h1 {
    min-width: 0;
}

.clock-generator-heading h1 {
    font-size: 1.55rem;
}

.breadcrumbs {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    color: var(--blue);
    font-size: .85rem;
    margin: 0 0 22px;
}

.crumb-separator { color: var(--muted); }

.textbook-mobile-breadcrumb,
.textbook-mobile-heading { display: none; }

.popular-grid {
    grid-template-columns: repeat(5, minmax(0, 1fr));
}

.popular-card {
    min-height: 150px;
    padding: 24px 18px;
    display: grid;
    gap: 8px;
    place-items: center;
    text-align: center;
}

.popular-card span, .section-card span, .subject-icon, .empty-icon {
    display: grid;
    place-items: center;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    color: var(--blue);
    background: var(--blue-soft);
    font-size: 1.4rem;
}

.subject-grid {
    grid-template-columns: repeat(2, minmax(280px, 1fr));
}

.subject-card {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 22px;
    padding: 34px;
    align-items: start;
}

.subject-card h2, .section-card h2, .material-card h2, .preview-card h2, .generator-form h2, .admin-panel h2 {
    margin: 0 0 8px;
    font-size: 1.2rem;
}

.section-grid {
    grid-template-columns: repeat(5, minmax(150px, 1fr));
}

.section-card {
    min-height: 210px;
    display: grid;
    gap: 12px;
    place-items: center;
    text-align: center;
    padding: 24px 18px;
}

.section-card.disabled {
    opacity: .55;
    pointer-events: none;
}

.material-list, .text-preview-page {
    display: grid;
    gap: 18px;
}

.material-card {
    display: grid;
    grid-template-columns: 82px 1fr auto;
    gap: 22px;
    align-items: center;
    padding: 18px 22px;
}

.material-cover {
    width: 72px;
    height: 96px;
    display: grid;
    place-items: center;
    border-radius: 6px;
    color: white;
    background: linear-gradient(145deg, var(--purple), #59a7ff);
    font-weight: 900;
}

.material-cover img,
.book-cover-preview img,
.admin-book-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.material-card dl {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    margin: 12px 0 0;
}

.material-card dt {
    color: var(--muted);
    font-size: .75rem;
}

.material-card dd {
    margin: 0;
    font-weight: 700;
}

.textbook-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 16px;
}

.textbook-search {
    display: grid;
    gap: 8px;
    max-width: 680px;
    min-width: 0;
    margin-bottom: 24px;
}

.textbook-search > label:first-child { font-weight: 700; }
.textbook-search input:not([type="checkbox"]) {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--line);
    border-radius: 8px;
    font: inherit;
}
.textbook-search-filters { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 160px), 1fr)); gap: 12px; }
.textbook-search-filters > div { display: grid; gap: 6px; min-width: 0; }
.textbook-search-scope { display: flex; align-items: center; gap: 8px; min-width: 0; }
.textbook-search-validation { margin: 0; color: var(--danger, #a32323); }
.textbook-search-clear { justify-self: start; }
.textbook-empty-clear { display: block; margin: 12px auto 0; }
.textbook-catalog-path { margin: 0 0 6px; color: var(--muted); }

.textbook-pagination {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 12px;
    min-width: 0;
    margin-top: 24px;
}

.textbook-pagination .btn,
.textbook-pagination span {
    min-width: 0;
}

.textbook-pagination span {
    overflow-wrap: anywhere;
    text-align: center;
}

.textbook-card {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    min-width: 0;
    padding: 12px 18px 16px;
}

.textbook-card .material-cover {
    width: 100%;
    height: 286px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    background: transparent;
    color: white;
}

.textbook-card .material-cover img {
    display: block;
    width: auto;
    max-width: 100%;
    height: auto;
    max-height: 100%;
    object-fit: contain;
    box-shadow: 0 5px 14px rgb(16 43 91 / 12%);
}

.textbook-card .material-cover span {
    display: grid;
    place-items: center;
    width: min(220px, 100%);
    height: 100%;
    border-radius: 5px;
    background: linear-gradient(145deg, #1765d7, #24a267);
}

.textbook-card .material-body {
    margin-top: 14px;
    min-width: 0;
    overflow-wrap: anywhere;
}

.textbook-card h2 {
    margin-bottom: 4px;
    font-size: 1rem;
    line-height: 1.35;
}

.textbook-card .textbook-author,
.textbook-card .textbook-publication {
    margin: 0;
    color: var(--muted);
    line-height: 1.4;
}

.textbook-mobile-year { display: none; }

.textbook-open {
    align-self: flex-start;
    margin-top: auto;
    padding: 8px 0 0;
    border: 0;
    background: none;
    color: var(--blue);
    cursor: pointer;
    font: inherit;
    font-weight: 700;
}

.textbook-open:hover { text-decoration: underline; }
.textbook-open:focus-visible { outline: 2px solid var(--blue); outline-offset: 3px; }

.textbook-detail {
    display: grid;
    grid-template-columns: minmax(220px, 320px) minmax(0, 1fr);
    gap: 36px;
    align-items: start;
    min-width: 0;
}

.textbook-detail-cover {
    display: grid;
    place-items: center;
    width: 100%;
    aspect-ratio: 3 / 4;
    overflow: hidden;
    border-radius: 10px;
    background: transparent;
    color: white;
    font-weight: 900;
}

.textbook-detail-cover img {
    display: block;
    width: auto;
    max-width: 100%;
    height: auto;
    max-height: 100%;
    object-fit: contain;
    box-shadow: 0 8px 24px rgb(16 43 91 / 14%);
}

.textbook-detail-cover span {
    display: grid;
    place-items: center;
    width: 100%;
    height: 100%;
    border-radius: 10px;
    background: linear-gradient(145deg, #1765d7, #24a267);
}

.textbook-detail-content {
    min-width: 0;
    overflow-wrap: anywhere;
}

.textbook-detail-heading { margin-top: 0; }

.textbook-detail-metadata {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px 28px;
    margin: 28px 0;
}

.textbook-detail-metadata div { min-width: 0; }

.textbook-detail-metadata dt {
    color: var(--muted);
    font-size: .82rem;
}

.textbook-detail-metadata dd {
    margin: 4px 0 0;
    font-weight: 700;
}

.textbook-detail-download {
    display: inline-flex;
    justify-content: center;
}

@media (max-width: 1100px) {
    .textbook-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

.generator-layout {
    display: grid;
    grid-template-columns: 360px 1fr;
    gap: 28px;
}

.generator-layout > .alert {
    grid-column: 1 / -1;
    margin-top: 0;
}

.generator-form label {
    display: grid;
    grid-template-columns: 1fr 120px;
    gap: 12px;
    align-items: center;
    margin: 8px 0;
}

.generator-form input, .generator-form select {
    width: 100%;
    min-height: 40px;
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 8px 10px;
    color: var(--ink);
    background: white;
}

.admin-form input, .admin-form textarea, .admin-form select, .admin-login-card input {
    width: 100%;
    min-height: 42px;
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 9px 12px;
    color: var(--ink);
    background: white;
}

.generator-form .check-row {
    grid-template-columns: auto 1fr;
}

.check-row input {
    width: 20px;
    height: 20px;
}

.actions-row {
    display: flex;
    gap: 14px;
    margin-top: 24px;
}

.btn,
.btn-primary,
.btn-success {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 44px;
    padding: 0 22px;
    border: 1px solid transparent;
    border-radius: 8px;
}

.btn {
    white-space: nowrap;
    cursor: pointer;
}

.actions-row .btn {
    min-width: 136px;
}

.btn-primary { color: white; background: var(--blue); }
.btn-success { color: white; background: var(--green); }
.btn-outline { color: var(--blue); border-color: var(--line); background: white; }
.btn:disabled { opacity: .6; cursor: wait; }

.exercise-list {
    display: grid;
    grid-template-columns: repeat(var(--exercise-columns, 1), minmax(0, 1fr));
    gap: 14px;
    padding-left: 26px;
}

.exercise-list-plain {
    list-style: none;
    padding-left: 0;
}

.exercise-list li {
    min-width: 0;
}

/* Narrow multi-column previews must keep the expression and answer slot together instead of wrapping the blank to its own line. */
.exercise-prompt {
    display: inline-flex;
    align-items: baseline;
    gap: 4px;
    min-width: 0;
    white-space: nowrap;
}

.exercise-answer-slot {
    /* The fixed slot replaces text underscores so hidden blanks and visible answers occupy the same line area. */
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    min-height: 1.1em;
    border-bottom: 1px solid currentColor;
    line-height: 1;
    white-space: nowrap;
}

.exercise-answer-slot strong {
    line-height: 1;
}

.fraction-exercise-list {
    gap: 18px 14px;
}

.fraction-exercise-prompt {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    min-width: 0;
    white-space: nowrap;
}

.stacked-fraction {
    display: inline-grid;
    grid-template-rows: auto auto;
    min-width: 1.5em;
    color: inherit;
    font-size: .92em;
    line-height: 1;
    text-align: center;
    vertical-align: middle;
}

.fraction-numerator {
    padding: 0 3px 2px;
    border-bottom: 1px solid currentColor;
}

.fraction-denominator {
    padding: 2px 3px 0;
}

.fraction-operation {
    min-width: 1ch;
    text-align: center;
}

.fraction-answer-slot {
    width: 52px;
    min-height: 2.2em;
}

.fraction-answer-slot strong {
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.worksheet-preview-page-header,
.clock-preview-page-header {
    min-width: 0;
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: start;
    gap: 12px;
    color: var(--ink);
}

.worksheet-preview-page-header h3,
.clock-preview-page-header h3 {
    min-width: 0;
    margin: 0;
    overflow-wrap: anywhere;
    /* Keep browser worksheet preview titles aligned with the 20pt PDF worksheet header size. */
    font-size: 20px;
    line-height: 1.2;
}

.worksheet-preview-page-header time {
    color: var(--muted);
    font-size: .82rem;
    font-weight: 700;
    line-height: 1.2;
    text-align: right;
    white-space: nowrap;
}

.clock-preview-pages {
    display: grid;
    justify-items: center;
    gap: 22px;
}

.clock-preview-pages.is-scrollable {
    max-height: min(72vh, 900px);
    overflow-y: auto;
    padding-right: 8px;
    overscroll-behavior: contain;
}

.clock-preview-page {
    width: 100%;
    max-width: 680px;
    aspect-ratio: 595 / 842;
    padding: clamp(14px, 4%, 32px);
    border: 1px solid var(--line);
    background: white;
    display: grid;
    grid-template-rows: auto minmax(0, 1fr);
    gap: clamp(8px, 1.5vw, 14px);
}

.clock-preview-page-header time {
    color: var(--muted);
    font-size: clamp(.62rem, 1.4vw, .82rem);
    font-weight: 700;
    line-height: 1.2;
    text-align: right;
    white-space: nowrap;
}

.clock-preview-page-grid {
    height: 100%;
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    grid-template-rows: repeat(5, minmax(0, 1fr));
    gap: clamp(6px, 1.5vw, 14px);
}

.clock-preview-cell {
    position: relative;
    min-width: 0;
    min-height: 0;
    display: grid;
    grid-template-rows: minmax(0, 1fr) 14px 18px;
    gap: 4px;
    align-items: start;
    justify-items: center;
}

.clock-exercise-number {
    position: absolute;
    top: 0;
    left: 0;
    color: var(--ink);
    font-size: clamp(.68rem, 1.4vw, .82rem);
    font-weight: 700;
    line-height: 1;
}

.clock-preview-cell img {
    /* The clock face is constrained by the image row so the answer line keeps its own row on narrow previews. */
    display: block;
    width: auto;
    max-width: 100%;
    height: 100%;
    max-height: 100%;
    min-height: 0;
    aspect-ratio: 1;
    object-fit: contain;
}

.clock-answer-line {
    display: block;
    justify-self: center;
    width: min(96px, 70%);
    height: 12px;
    border-bottom: 1.5px solid currentColor;
}

.scale-exercise-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 14px;
    row-gap: 7px;
}

.scale-exercise-cell {
    display: grid;
    justify-items: center;
    gap: 4px;
    position: relative;
    min-width: 0;
}

.scale-exercise-cell > span:first-child:not(.scale-answer-line) {
    position: absolute;
    top: 0;
    left: 0;
}

.scale-exercise-cell img {
    width: 100%;
    max-width: 480px;
    object-fit: contain;
}

.scale-exercise-cell img.scale-image-ruler {
    aspect-ratio: 4 / 1;
}

.scale-exercise-cell img.scale-image-semicircle {
    aspect-ratio: 24 / 13;
}

.point-placement-scale-cell {
    align-items: stretch;
    gap: 0;
}

.point-placement-scale-grid {
    row-gap: var(--point-placement-row-gap, 7px);
}

.scale-point-instructions {
    margin: 0 0 var(--point-placement-instruction-image-gap, 13px);
    padding-left: 20px;
    font-size: .85rem;
    line-height: var(--point-placement-instruction-line-height, 19px);
    overflow-wrap: anywhere;
}

.point-placement-scale-cell.has-exercise-number .scale-point-instructions {
    margin-left: var(--point-placement-number-width, 34px);
}

.scale-answer-line {
    display: block;
    width: 100px;
    border-bottom: 1px solid currentColor;
    height: 5px;
}

.worksheet-builder-shell {
    display: grid;
    gap: 20px;
    /* Keep the builder attached to the normal content start while using only right-side spare padding for the wider 1390px cap. */
    width: min(1390px, calc(100% + 40px));
    margin-inline: 0 -40px;
}

.worksheet-builder-toolbar {
    display: grid;
    grid-template-columns: repeat(4, minmax(140px, 1fr)) minmax(170px, auto) auto;
    gap: 14px;
    align-items: end;
    padding: 18px;
}

.worksheet-builder-toolbar label {
    display: grid;
    gap: 7px;
    color: var(--muted);
    font-size: .82rem;
    font-weight: 800;
}

.worksheet-header-toggle {
    display: flex;
    gap: 8px;
    align-self: center;
    align-items: center;
    color: var(--ink);
}

.worksheet-header-controls {
    display: grid;
    gap: 6px;
    align-self: center;
    min-width: 0;
    padding: 8px 10px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: #fbfdff;
}

.worksheet-header-controls .check-row {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    gap: 8px;
    align-items: center;
    margin: 0;
    color: var(--ink);
    font-size: .8rem;
    font-weight: 700;
    line-height: 1.2;
}

.worksheet-header-controls .check-row span {
    min-width: 0;
    overflow-wrap: anywhere;
}

.worksheet-header-controls .worksheet-header-toggle {
    align-self: stretch;
    padding-bottom: 6px;
    border-bottom: 1px solid var(--line);
    font-weight: 800;
}

.worksheet-builder-toolbar input:not([type="checkbox"]),
.worksheet-builder-toolbar select {
    width: 100%;
    min-height: 40px;
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 8px 10px;
    color: var(--ink);
    background: white;
}

.worksheet-header-controls input[type="checkbox"] {
    width: 18px;
    height: 18px;
    min-height: 0;
    margin: 0;
    padding: 0;
    flex: 0 0 auto;
    accent-color: var(--blue);
}

.worksheet-builder-save {
    justify-self: end;
}

.worksheet-regenerate-preview {
    justify-self: start;
    margin-top: 4px;
}

.worksheet-builder-grid {
    display: grid;
    grid-template-columns: minmax(320px, 360px) minmax(688px, 1fr) minmax(320px, 360px);
    gap: 20px;
    align-items: start;
}

.worksheet-type-panel,
.worksheet-canvas-panel,
.worksheet-settings-panel {
    min-width: 0;
}

.worksheet-builder-panel-header {
    margin-bottom: 16px;
}

.worksheet-type-panel h2,
.worksheet-settings-panel h2,
.worksheet-canvas-title-row h2 {
    margin: 0 0 6px;
    font-size: 1.05rem;
}

.worksheet-type-panel p,
.worksheet-settings-panel p,
.worksheet-canvas-title-row p {
    margin: 0;
    color: var(--muted);
    line-height: 1.45;
}

.worksheet-type-list {
    display: grid;
    gap: 10px;
}

.worksheet-type-card {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: 10px;
    align-items: center;
    padding: 12px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: #fbfdff;
    cursor: grab;
}

.worksheet-type-card:active {
    cursor: grabbing;
}

.worksheet-type-icon {
    display: grid;
    place-items: center;
    width: 38px;
    height: 38px;
    border-radius: 8px;
    color: var(--blue);
    background: var(--blue-soft);
    font-weight: 900;
}

.worksheet-type-card strong,
.worksheet-type-card small {
    display: block;
    min-width: 0;
}

.worksheet-type-card strong {
    overflow-wrap: anywhere;
    font-size: .92rem;
}

.worksheet-type-card small {
    margin-top: 4px;
    color: var(--muted);
    font-size: .78rem;
    line-height: 1.35;
}

.worksheet-drag-handle {
    color: var(--muted);
    font-weight: 900;
}

.worksheet-canvas-title-row {
    display: flex;
    justify-content: space-between;
    gap: 14px;
    margin-bottom: 14px;
}

.worksheet-canvas-title-row span {
    flex: 0 0 auto;
    color: var(--blue);
    font-size: .82rem;
    font-weight: 900;
}

.worksheet-drop-zone {
    overflow: auto;
    border: 1px dashed #bad0f3;
    border-radius: 8px;
    background: #f3f8ff;
}

.worksheet-a4-pages {
    display: grid;
    width: max-content;
    min-width: 100%;
    gap: 22px;
    padding: 16px;
    justify-items: center;
}

.worksheet-a4-page {
    position: relative;
    container-type: inline-size;
    width: var(--worksheet-page-width, 595px);
    min-width: var(--worksheet-page-width, 595px);
    height: var(--worksheet-page-height, 842px);
    min-height: var(--worksheet-page-height, 842px);
    /* Oversized generated blocks are warned in the UI and must remain visible instead of being silently clipped. */
    overflow: visible;
    outline: 1px solid #cfd9e8;
    background: white;
    box-shadow: 0 14px 30px rgba(15, 34, 74, .12);
}

.worksheet-a4-page-content {
    position: absolute;
    inset: 0;
    /* Keep exercise overflow visible while preventing content from contributing to the A4 frame height. */
    overflow: visible;
    padding: var(--worksheet-page-margin, 42px);
    font-size: 12px;
}

.worksheet-paper-header {
    display: block;
    margin: 0 0 var(--worksheet-header-bottom-gap, 16px);
    color: #0c1742;
    text-align: center;
}

.worksheet-paper-header h3 {
    margin: 0;
    height: var(--worksheet-header-title-height, 30px);
    overflow: hidden;
    font-size: 20px;
    line-height: 24px;
}

.worksheet-paper-header strong {
    display: block;
    height: var(--worksheet-header-class-height, 20px);
    overflow: hidden;
    font-size: 12px;
    line-height: 16px;
}

.worksheet-paper-header p {
    height: var(--worksheet-header-student-line-height, 28px);
    margin: 0;
    overflow: hidden;
    font-size: 12px;
    line-height: 18px;
    text-align: left;
}

.worksheet-exercise-stack {
    display: grid;
    gap: var(--worksheet-block-gap, 14px);
}

.worksheet-exercise-block {
    position: relative;
    min-width: 0;
    cursor: pointer;
}

.worksheet-exercise-block.selected::before {
    position: absolute;
    z-index: 1;
    inset: -6px calc((var(--worksheet-page-margin, 42px) - 6px) * -1);
    border: 1px solid var(--blue);
    border-radius: 8px;
    box-shadow: 0 0 0 3px rgba(21, 91, 220, .12);
    pointer-events: none;
    content: "";
}

.worksheet-exercise-block h4 {
    height: var(--worksheet-block-title-height, 28px);
    margin: 0;
    overflow: hidden;
    font-size: 13px;
    line-height: 18px;
}

.worksheet-exercise-block.continuation h4 {
    color: var(--muted);
}

.worksheet-preview-overflow {
    position: absolute;
    z-index: 2;
    top: var(--worksheet-block-title-height, 28px);
    right: 0;
    max-width: 70%;
    margin: 0;
    color: #9b2f18;
    font-size: .78rem;
    font-weight: 700;
}

.worksheet-selected-marker {
    position: absolute;
    z-index: 2;
    left: -34px;
    top: -4px;
    display: grid;
    place-items: center;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    color: white;
    background: var(--blue);
    font-size: .78rem;
    font-weight: 900;
}

.worksheet-block-actions {
    position: absolute;
    z-index: 2;
    top: -4px;
    right: -34px;
    display: flex;
    gap: 6px;
}

.worksheet-block-actions button {
    display: grid;
    place-items: center;
    width: 28px;
    height: 28px;
    border: 1px solid #c8daf8;
    border-radius: 8px;
    color: var(--blue);
    background: white;
    cursor: pointer;
}

.worksheet-expression-list {
    grid-template-columns: repeat(var(--worksheet-expression-columns, 3), minmax(0, 1fr));
    grid-auto-rows: var(--worksheet-item-height, 26px);
    column-gap: var(--worksheet-column-gap, 18px);
    row-gap: var(--worksheet-row-gap, 0px);
    margin: 0;
    font-size: 12px;
    line-height: 16px;
}

.worksheet-expression-list.exercise-list {
    /* Worksheet previews carry the shared exercise-list class, so this scoped selector keeps the selected worksheet columns ahead of later mobile exercise-list fallbacks. */
    grid-template-columns: repeat(var(--worksheet-expression-columns, 3), minmax(0, 1fr));
}

.worksheet-expression-list > li {
    height: var(--worksheet-item-height, 26px);
    overflow: hidden;
}

/* Collapse before the 220px sidebar + 40px preserved content padding + 1368px grid minimum can exceed the 1628px viewport. */
@media (max-width: 1628px) {
    .worksheet-builder-shell {
        width: 100%;
        margin-inline: 0;
    }

    .worksheet-builder-grid {
        grid-template-columns: 1fr;
    }
}

.worksheet-drop-hint {
    position: absolute;
    left: 34px;
    right: 34px;
    bottom: 22px;
    padding-top: 12px;
    border-top: 1px dashed #d8e2ef;
    color: #90a0bb;
    font-size: .82rem;
    text-align: center;
}

.worksheet-settings-form {
    display: grid;
    gap: 0;
}

.worksheet-settings-form fieldset {
    display: grid;
    gap: 10px;
    margin: 0;
    padding: 0;
    border: 0;
}

.worksheet-settings-form legend {
    margin-bottom: 2px;
    color: var(--ink);
    font-weight: 400;
}

.worksheet-preview-status,
.worksheet-preview-error {
    margin: 0;
    color: var(--muted);
    font-size: .86rem;
}

.worksheet-preview-error {
    color: #b42318;
}

.worksheet-clock-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    grid-auto-rows: var(--worksheet-item-height, 126px);
    column-gap: var(--worksheet-column-gap, 18px);
    row-gap: var(--worksheet-row-gap, 0px);
}

.worksheet-clock-created-at {
    display: block;
    height: 14px;
    margin: 0;
    overflow: hidden;
    color: var(--muted);
    font-size: .76rem;
    font-weight: 700;
    text-align: right;
}

.worksheet-clock-cell {
    grid-template-rows: minmax(0, 1fr) 10px 16px;
    height: var(--worksheet-item-height, 126px);
    min-height: 0;
}

.worksheet-exercise-block .scale-exercise-grid {
    grid-auto-rows: var(--worksheet-item-height);
    column-gap: var(--worksheet-column-gap, 18px);
    row-gap: var(--worksheet-row-gap, 0px);
}

.worksheet-exercise-block .scale-exercise-cell {
    height: var(--worksheet-item-height);
    min-height: 0;
    overflow: hidden;
}

.worksheet-settings-form small {
    color: var(--muted);
    font-size: .76rem;
    line-height: 1.35;
}

.state-panel, .empty-state {
    display: grid;
    place-items: center;
    text-align: center;
    gap: 12px;
    min-height: 180px;
    color: var(--muted);
}

.spinner {
    width: 34px;
    height: 34px;
    border: 3px solid var(--line);
    border-top-color: var(--blue);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

.alert {
    padding: 12px 14px;
    margin: 12px 0;
    border-radius: 8px;
    font-weight: 700;
}

.alert-danger { color: #8b1d1d; background: #fff0f0; border: 1px solid #ffd4d4; }
.alert-success { color: #116333; background: #eaf8f0; border: 1px solid #ccebd9; }
.alert-info { color: #174282; background: var(--blue-soft); border: 1px solid #d4e5ff; }

.admin-login-page {
    min-height: 100vh;
    display: grid;
    place-items: center;
    align-content: center;
    gap: 24px;
    background: linear-gradient(180deg, #f9fbff, #edf4ff);
}

.admin-login-card {
    width: min(380px, calc(100vw - 32px));
    display: grid;
    gap: 14px;
    padding: 34px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: white;
    box-shadow: var(--shadow);
}

.admin-login-card h1 {
    margin: 0 0 8px;
    text-align: center;
    font-size: 1.4rem;
}

.admin-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.admin-nav-grid {
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

.admin-nav-grid a {
    padding: 28px;
    color: var(--blue);
    font-weight: 900;
}

.admin-two-column {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
}

.admin-panel {
    padding: 22px;
}

.admin-books-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 16px;
}

.admin-books-header p {
    margin: 0;
    color: var(--muted);
}

.admin-books-create-panel[hidden] {
    display: none;
}

.admin-books-search {
    display: grid;
    grid-template-columns: minmax(200px, 1.5fr) repeat(3, minmax(140px, 1fr)) minmax(112px, .7fr) minmax(112px, .7fr);
    align-items: end;
    gap: 16px;
    margin-bottom: 16px;
    padding: 20px;
}

.admin-books-search label {
    display: grid;
    gap: 8px;
    min-width: 0;
    color: #4b6091;
    font-size: .9rem;
    font-weight: 600;
}

.admin-books-search input,
.admin-books-search select {
    width: 100%;
    min-width: 0;
    height: 44px;
    border: 1px solid #dce5f3;
    border-radius: 8px;
    background: white;
    color: var(--ink);
}

.admin-books-search-input {
    display: flex;
    align-items: center;
    height: 44px;
    border: 1px solid #dce5f3;
    border-radius: 8px;
    background: white;
}

.admin-books-search-input svg {
    width: 19px;
    height: 19px;
    margin-left: 14px;
    flex: none;
    color: #5b70a0;
}

.admin-books-search .admin-books-search-input input {
    height: 42px;
    border: 0;
    outline-offset: -2px;
}

.admin-books-search .btn { height: 44px; }
.admin-books-empty { text-align: center; color: var(--muted); }

@media (max-width: 1100px) {
    .admin-books-search { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (max-width: 680px) {
    .admin-books-search { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .admin-books-search label:first-child { grid-column: 1 / -1; }
}

.admin-table {
    width: 100%;
    border-collapse: collapse;
    font-size: .9rem;
}

.admin-table-scroll {
    overflow-x: auto;
}

.admin-table-scroll .admin-table {
    min-width: 720px;
}

.admin-pagination {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 16px;
}

.admin-table th, .admin-table td {
    padding: 10px 8px;
    border-bottom: 1px solid var(--line);
    text-align: left;
    vertical-align: top;
}

.admin-books-list {
    padding: 0;
    min-width: 0;
}

.admin-books-table-scroll {
    overflow-x: auto;
}

.admin-books-list .admin-table {
    border-collapse: separate;
    border-spacing: 0;
    min-width: 1100px;
}

.admin-books-list .admin-table th {
    padding: 18px 12px;
    color: #4b6091;
    background: #f4f8ff;
    font-weight: 700;
}

.admin-books-list .admin-table th:first-child { border-top-left-radius: 8px; }
.admin-books-list .admin-table th:last-child { border-top-right-radius: 8px; }

.admin-books-list .admin-table td {
    padding: 10px 12px;
    vertical-align: middle;
}

.admin-books-list .admin-book-cover {
    width: 76px;
    height: 104px;
}

.admin-books-list .admin-book-author {
    overflow-wrap: anywhere;
}

.admin-books-list .admin-book-download a {
    color: var(--blue);
}

.admin-book-visibility {
    display: inline-block;
    padding: 5px 12px;
    border-radius: 7px;
    color: #4b6091;
    background: #edf1f6;
    white-space: nowrap;
}

.admin-book-edit-actions {
    display: grid;
}

.admin-book-edit-action {
    padding: 9px 0;
    border: 0;
    color: var(--blue);
    background: transparent;
    text-align: left;
    white-space: nowrap;
    cursor: pointer;
}

.admin-book-edit-action + .admin-book-edit-action {
    border-top: 1px solid var(--line);
}

.admin-book-edit-action:disabled {
    opacity: .6;
    cursor: wait;
}

.admin-books-list .admin-pagination {
    margin: 0;
    padding: 16px;
}

.admin-books-list .admin-table .admin-book-metadata-cell {
    padding: 0 16px 16px;
}

.admin-form.admin-book-metadata-editor {
    gap: 20px;
    margin: 0;
    padding: 22px 24px;
    border: 1px solid #dce9fb;
    border-radius: 10px;
    background: #f4f8ff;
}

.admin-book-metadata-heading h2 {
    margin: 0 0 6px;
    font-size: 1.1rem;
}

.admin-book-metadata-heading p {
    margin: 0;
    color: var(--muted);
}

.admin-book-metadata-fields {
    display: grid;
    gap: 18px;
}

.admin-book-metadata-fields-primary {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.admin-book-metadata-fields-secondary {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.admin-book-metadata-fields label {
    display: grid;
    gap: 8px;
    min-width: 0;
    color: #40547f;
    font-size: .9rem;
}

.admin-book-metadata-fields input[readonly] {
    color: #64718f;
    background: #edf1f6;
    cursor: default;
}

.admin-book-metadata-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
}

.admin-book-metadata-actions .btn {
    min-width: 136px;
}

.admin-form {
    display: grid;
    gap: 10px;
    margin-top: 18px;
}

.grid-form {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-form textarea {
    grid-column: 1 / -1;
    min-height: 90px;
}

.admin-file-field {
    display: grid;
    gap: 8px;
    color: var(--muted);
    font-weight: 800;
}

.file-picker {
    position: relative;
    display: flex;
    align-items: center;
    gap: 12px;
    width: 100%;
    min-height: 42px;
    padding: 7px 10px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: white;
    cursor: pointer;
}

.file-picker-button {
    flex: 0 0 auto;
    pointer-events: none;
}

.file-picker-name {
    min-width: 0;
    overflow: hidden;
    color: var(--ink);
    font-weight: 700;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.file-picker-input {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    cursor: pointer;
    opacity: 0;
}

.book-cover-preview,
.admin-book-cover {
    width: 72px;
    height: 96px;
    display: grid;
    place-items: center;
    overflow: hidden;
    border-radius: 8px;
    color: white;
    background: linear-gradient(145deg, #155bdc, #21a657);
    font-size: .72rem;
    font-weight: 900;
    text-align: center;
}

#blazor-error-ui {
    display: none;
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    padding: 12px 16px;
    color: white;
    background: #9c1c1c;
}

#blazor-error-ui .reload { color: white; text-decoration: underline; }
#blazor-error-ui .dismiss { cursor: pointer; float: right; }

@media (max-width: 900px) {
    html:has(.mobile-drawer.open),
    body:has(.mobile-drawer.open) { overflow: hidden !important; }
    .textbook-desktop-breadcrumb,
    .textbook-desktop-heading { display: none; }
    .textbook-mobile-heading { display: inline; }
    .textbook-mobile-breadcrumb {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 10px;
        margin: 0 0 22px;
        color: var(--blue);
        font-size: .95rem;
    }
    .textbook-mobile-breadcrumb a {
        min-width: 0;
        overflow-wrap: anywhere;
    }
    .textbook-grid { grid-template-columns: minmax(0, 1fr); }
    .textbook-card {
        display: grid;
        grid-template-columns: clamp(86px, 29vw, 140px) minmax(0, 1fr) 12px;
        grid-template-rows: minmax(0, 1fr) auto;
        column-gap: clamp(10px, 3vw, 22px);
        align-items: start;
        padding: 14px;
    }
    .textbook-card .material-cover {
        grid-column: 1;
        grid-row: 1 / 3;
        width: 100%;
        height: clamp(116px, 39vw, 190px);
        align-self: center;
    }
    .textbook-card .material-body {
        grid-column: 2;
        grid-row: 1;
        margin-top: 0;
    }
    .textbook-card .textbook-publication { display: none; }
    .textbook-card .textbook-mobile-year {
        display: block;
        margin: 6px 0 0;
        color: var(--muted);
        line-height: 1.4;
    }
    .textbook-card .textbook-open {
        grid-column: 2;
        grid-row: 2;
        justify-self: start;
        margin-top: 10px;
        padding-top: 0;
    }
    .textbook-card::after {
        content: '';
        grid-column: 3;
        grid-row: 1 / 3;
        align-self: center;
        width: 9px;
        height: 9px;
        border-top: 2px solid var(--muted);
        border-right: 2px solid var(--muted);
        transform: rotate(45deg);
    }
    .textbook-detail {
        grid-template-columns: minmax(0, 1fr);
        gap: 24px;
        width: 100%;
    }
    .textbook-detail-cover {
        width: min(280px, 100%);
        justify-self: center;
    }
    .textbook-detail-metadata { grid-template-columns: minmax(0, 1fr); }
    .textbook-detail-download { width: 100%; }
    .admin-book-metadata-fields-primary,
    .admin-book-metadata-fields-secondary { grid-template-columns: 1fr; }
    .app-shell { display: block; }
    .mobile-drawer-backdrop.open {
        display: block;
        position: fixed;
        inset: 0;
        z-index: 10;
        background: rgba(5, 16, 43, .48);
    }
    .mobile-drawer {
        position: fixed;
        top: 0;
        right: 0;
        z-index: 11;
        width: min(80vw, 360px);
        min-width: 0;
        height: 100vh;
        height: 100dvh;
        overflow-y: auto;
        overscroll-behavior: contain;
        background: white;
        box-shadow: -10px 0 30px rgba(5, 16, 43, .14);
        transform: translateX(100%);
        visibility: hidden;
        pointer-events: none;
        transition: transform .2s ease, visibility .2s;
    }
    .mobile-drawer.open {
        transform: translateX(0);
        visibility: visible;
        pointer-events: auto;
    }
    .mobile-drawer-close {
        display: grid;
        place-items: center;
        position: absolute;
        top: calc(20px + env(safe-area-inset-top));
        right: calc(14px + env(safe-area-inset-right));
        z-index: 1;
        width: 40px;
        height: 40px;
        border: 0;
        background: transparent;
        color: var(--ink);
        cursor: pointer;
        font-size: 2rem;
        line-height: 1;
    }
    .sidebar {
        width: 100%;
        height: auto;
        min-height: 100%;
        padding: calc(24px + env(safe-area-inset-top)) calc(18px + env(safe-area-inset-right)) calc(24px + env(safe-area-inset-bottom)) calc(18px + env(safe-area-inset-left));
        overflow: visible;
        border-right: 0;
    }
    .sidebar-brand { padding-right: 38px; }
    .sidebar-nav {
        grid-template-columns: minmax(0, 1fr);
        gap: 0;
        margin-top: 22px;
    }
    .sidebar-nav > a,
    .sidebar-nav > .grade-group {
        border-top: 1px solid var(--line);
    }
    .sidebar-nav > a,
    .grade-group-toggle,
    .grade-links a {
        min-height: 48px;
        padding: 10px 12px;
        font-size: 1rem;
    }
    .sidebar-nav > a {
        gap: 16px;
        font-weight: 500;
    }
    .sidebar-nav > a:last-child { align-items: flex-start; }
    .sidebar-nav > a:last-child .nav-icon { margin-top: 2px; }
    .sidebar-nav > a .link-chevron {
        display: block;
        flex: none;
        width: 18px;
        height: 18px;
        margin-left: auto;
    }
    .desktop-nav-icon,
    .grade-group-header { display: none !important; }
    .nav-icon {
        display: block;
        flex: none;
        width: 23px;
        height: 23px;
    }
    .grade-group { display: block; min-width: 0; }
    .grade-group-toggle {
        display: flex;
        align-items: center;
        gap: 16px;
        width: 100%;
        border: 0;
        border-radius: 8px;
        background: transparent;
        color: #12204b;
        cursor: pointer;
        text-align: left;
        font: inherit;
    }
    .grade-group-toggle-label {
        flex: 1;
        min-width: 0;
        overflow-wrap: anywhere;
    }
    .group-chevron {
        flex: none;
        width: 18px;
        height: 18px;
        transform: rotate(-90deg);
    }
    .grade-group-toggle[aria-expanded="true"] .group-chevron { transform: none; }
    .grade-group-toggle.active {
        color: var(--blue);
        background: var(--blue-soft);
        font-weight: 700;
    }
    .grade-links {
        gap: 2px;
        margin: 2px 0 10px 29px;
        padding-left: 14px;
        border-left: 1px solid var(--line);
    }
    .grade-links a {
        display: flex;
        align-items: center;
        overflow-wrap: anywhere;
        font-weight: 500;
    }
    .grade-links a.active { font-weight: 700; }
    .sidebar-nav a:focus-visible,
    .grade-group-toggle:focus-visible {
        outline: 2px solid var(--blue);
        outline-offset: 2px;
    }
    .sidebar-nav > a span:not(.desktop-nav-icon) { min-width: 0; overflow-wrap: anywhere; }
    .topbar { justify-content: space-between; gap: 12px; padding: 14px 18px; }
    .topbar-search-disabled { display: flex; }
    .brand-inline { display: flex; }
    .mobile-menu-button {
        display: flex;
        flex: none;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: 5px;
        width: 44px;
        height: 44px;
        padding: 0;
        border: 0;
        background: transparent;
        color: var(--ink);
        cursor: pointer;
    }
    .mobile-menu-button span {
        width: 28px;
        height: 2px;
        border-radius: 1px;
        background: currentColor;
    }
    .content-shell { padding: 12px 18px 38px; }
    .hero-panel, .generator-layout, .generator-layout.rounding-generator-layout, .admin-two-column, .worksheet-builder-toolbar, .worksheet-builder-grid { grid-template-columns: 1fr; }
    .page-heading-row { display: block; }
    .hero-panel { padding: 32px 24px; }
    .stage-grid { grid-template-columns: 1fr; margin: 18px 0 34px; }
    .popular-grid, .grade-card-grid, .section-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .subject-grid, .admin-nav-grid { grid-template-columns: 1fr; }
    .material-card:not(.textbook-card) { grid-template-columns: 72px 1fr; }
    .material-card .btn { grid-column: 1 / -1; }
    .exercise-list { grid-template-columns: 1fr; }
    .worksheet-builder-save { justify-self: stretch; }
    .worksheet-a4-page { min-width: var(--worksheet-page-width, 595px); }
}

@media (max-width: 560px) {
    .popular-grid, .grade-card-grid, .section-grid, .grid-form { grid-template-columns: 1fr; }
    .hero-panel h1 { font-size: 1.9rem; }
    .hero-art { display: none; }
}