.book{--book-ink:#1d1d1f;--book-ink-soft:#4a4a52;--book-accent:#c8203a;--book-accent-ink:#ffffff;--book-tint:color-mix(in srgb,var(--book-accent) 10%,var(--g-paper));--book-rule:color-mix(in srgb,var(--book-accent) 70%,transparent);--book-a:#c8203a;--book-b:#1f6fb2}.book[data-tone=blue]{--book-accent:#1f5fa8;--book-a:#1f5fa8;--book-b:#b8452a}.book[data-tone=violet]{--book-accent:#5b3fa8;--book-a:#5b3fa8;--book-b:#0f7a6b}.book-reader{display:grid;gap:.75rem}.book-bar{display:flex;align-items:center;gap:.5rem;flex-wrap:wrap;padding:.5rem .75rem;border-radius:.875rem;background:var(--surface-raised);border:1px solid color-mix(in srgb,var(--text-strong) 10%,transparent)}.book-bar-title{flex:1 1 12rem;min-width:0;text-align:center;line-height:1.25}.book-bar-title small{display:block;font-size:.6875rem;letter-spacing:.14em;text-transform:uppercase;color:var(--text-muted)}.book-tool{display:inline-flex;align-items:center;gap:.375rem;min-height:2.5rem;padding:0 .75rem;border-radius:.625rem;border:1px solid color-mix(in srgb,var(--text-strong) 14%,transparent);background:var(--surface);font-weight:700;font-size:.875rem;color:var(--text-strong)}.book-tool[aria-pressed=true]{background:var(--text-strong);color:var(--surface)}.book-tool:disabled{opacity:.4}.book-stage{position:relative;overflow:auto;border-radius:1rem;padding:.75rem;background:color-mix(in srgb,var(--text-strong) 6%,var(--surface))}.book-spread{display:grid;gap:.75rem;margin-inline:auto;max-width:64rem}@media (min-width:1100px){.book-spread[data-pages="2"]{grid-template-columns:1fr 1fr;gap:0}.book-spread[data-pages="2"]>.book-page:first-child{border-start-end-radius:0;border-end-end-radius:0;box-shadow:inset -18px 0 22px -18px rgb(0 0 0/.28),var(--g-shadow)}.book-spread[data-pages="2"]>.book-page:last-child{border-start-start-radius:0;border-end-start-radius:0;box-shadow:inset 18px 0 22px -18px rgb(0 0 0/.28),var(--g-shadow)}}.book-page{position:relative;color:var(--book-ink);background:var(--g-paper);border-radius:.5rem;box-shadow:var(--g-shadow);padding:1.25rem 1.25rem 2.5rem;min-height:20rem;overflow:hidden}@media (min-width:640px){.book-page{padding:1.75rem 2rem 3rem}}.book-page :where(p,li,td,th){color:var(--book-ink)}.book-folio{position:absolute;inset-block-end:.75rem;inset-inline:0;text-align:center;font-size:.75rem;font-weight:700;color:var(--book-ink-soft)}.book-opener{position:relative;margin:-1.25rem -1.25rem 1.25rem;padding:1.25rem 1.25rem 1rem;color:#fff;background:linear-gradient(110deg,color-mix(in srgb,var(--book-accent) 92%,#000) 0,var(--book-accent) 55%,color-mix(in srgb,var(--book-accent) 70%,#f5b04a) 100%)}@media (min-width:640px){.book-opener{margin:-1.75rem -2rem 1.5rem;padding:1.5rem 2rem 1.25rem}}.book-opener-no{display:inline-grid;place-items:center;min-width:3rem;height:3rem;padding:0 .5rem;border-radius:.5rem;background:rgb(255 255 255/.18);font-weight:900;font-size:1.75rem;line-height:1}.book-opener h2{margin-top:.5rem;font-weight:900;font-size:clamp(1.75rem,1.1rem + 2.6vw,2.75rem);line-height:1.05;letter-spacing:-.02em;color:#fff}.book-opener ul{margin-top:.75rem;display:grid;gap:.15rem;font-size:.875rem;font-weight:700}.book-page .book-opener :where(p,li,h2){color:#fff}.book-page .book-opener .book-sub{margin-top:.25rem;font-weight:700;color:rgb(255 255 255/.9)}.book-opener li:before{content:"▸ "}.book-opener .book-ref{margin-top:.75rem;font-size:.75rem;font-weight:700;opacity:.9}.book-page .book-refline{margin-bottom:.75rem;font-size:.75rem;font-weight:700;color:var(--book-ink-soft)}.book-sec{margin-top:1.25rem}.book-sec:first-child{margin-top:0}.book-sec-h{display:flex;align-items:baseline;gap:.5rem;padding-bottom:.35rem;border-bottom:2px solid var(--book-rule)}.book-sec-no{display:inline-grid;place-items:center;align-self:center;min-width:1.75rem;height:1.75rem;border-radius:.3rem;background:var(--book-accent);color:var(--book-accent-ink);font-weight:900;font-size:1rem}.book-sec-label{font-weight:900;font-size:1.125rem;letter-spacing:.02em;text-transform:uppercase;color:var(--book-ink)}.book-sec-title{font-weight:700;font-size:.9375rem;color:var(--book-ink-soft)}.book-task{display:flex;align-items:center;gap:.5rem;margin-top:.6rem;font-size:.875rem;color:var(--book-ink)}.book-listen{display:inline-grid;place-items:center;flex:none;width:2rem;height:2rem;border-radius:999px;background:var(--book-accent);color:#fff;box-shadow:0 1px 0 rgb(0 0 0/.15)}.book-listen[data-small]{width:1.5rem;height:1.5rem}.book-listen[aria-pressed=true]{background:var(--book-ink)}.book-listen svg{width:55%;height:55%}[data-speaking=true]{background:color-mix(in srgb,#ffd84d 55%,transparent)!important;border-radius:.3rem}.book-play{display:flex;flex-wrap:wrap;align-items:center;gap:.5rem;margin-top:1rem;padding:.6rem .75rem;border-radius:.6rem;background:var(--book-tint);border:1px dashed var(--book-rule);font-size:.875rem;color:var(--book-ink)}.book-play a,.book-play button{display:inline-flex;align-items:center;gap:.375rem;min-height:2.25rem;padding:0 .85rem;border-radius:999px;background:var(--book-accent);color:#fff;font-weight:800}.book-done{display:inline-grid;place-items:center;width:1.75rem;height:1.75rem;border-radius:999px;background:#2e9b4f;color:#fff}.book-media{margin-top:.75rem}.book-media audio,.book-media video{display:block;width:100%;border-radius:.5rem;background:#000}.book-media audio{background:transparent}.book-page .book-media figcaption{margin-top:.3rem;font-size:.6875rem;color:var(--book-ink-soft)}.book-group{margin-top:.85rem;font-size:.75rem;font-weight:900;letter-spacing:.12em;text-transform:uppercase;color:var(--book-accent)}.book-words{display:grid;gap:.4rem;margin-top:.4rem}@media (min-width:640px){.book-words{grid-template-columns:repeat(2,minmax(0,1fr))}}.book-word{display:grid;grid-template-columns:auto 1fr auto;gap:.15rem .6rem;align-items:center;padding:.45rem .6rem;border-radius:.5rem;background:color-mix(in srgb,#fff 55%,var(--g-paper));border:1px solid color-mix(in srgb,var(--g-paper-edge) 70%,transparent)}.book-word-pic{grid-row:span 2;font-size:1.6rem;line-height:1;width:2rem;text-align:center}.book-word-en{font-weight:800;color:var(--book-ink)}.book-word-ar{justify-self:end;font-size:.875rem;color:var(--book-ink-soft)}.book-word-ex{grid-column:2/4;font-size:.8125rem}.book-setting,.book-word-ex{font-style:italic;color:var(--book-ink-soft)}.book-setting{margin-top:.5rem;font-size:.875rem}.book-turns{display:grid;gap:.4rem;margin-top:.75rem}.book-turn{display:grid;grid-template-columns:minmax(3.5rem,max-content) 1fr;gap:.5rem;align-items:start;padding:.1rem .25rem}.book-speaker{justify-self:start;padding:.1rem .5rem;border-radius:.35rem;font-size:.8125rem;font-weight:800;color:#fff;background:var(--book-a)}.book-turn[data-side=b] .book-speaker{background:var(--book-b)}.book-line{padding:.3rem .6rem;border-radius:.5rem;background:color-mix(in srgb,var(--book-a) 9%,var(--g-paper));border:1px solid color-mix(in srgb,var(--book-a) 30%,transparent);color:var(--book-ink);font-size:.9375rem}.book-turn[data-side=b] .book-line{background:color-mix(in srgb,var(--book-b) 9%,var(--g-paper));border-color:color-mix(in srgb,var(--book-b) 30%,transparent)}.book-box{margin-top:1rem;border-radius:.6rem;overflow:hidden;border:1px solid var(--book-rule)}.book-box-h{padding:.35rem .75rem;background:var(--book-accent);color:#fff;font-weight:800;font-size:.8125rem;letter-spacing:.04em;text-transform:uppercase}.book-box-b{padding:.5rem .75rem;background:color-mix(in srgb,#fff 45%,var(--g-paper))}.book-pair{display:flex;justify-content:space-between;gap:1rem;padding:.25rem 0;border-bottom:1px dotted color-mix(in srgb,var(--g-paper-edge) 90%,transparent);font-size:.875rem}.book-pair:last-child{border-bottom:0}.book-pair [lang=ar]{color:var(--book-ink-soft)}.book-explain{margin-top:.6rem;display:grid;gap:.3rem;font-size:.9375rem}.book-table{width:100%;border-collapse:collapse;font-size:.9375rem}.book-table td{padding:.3rem .6rem;border-bottom:1px solid color-mix(in srgb,var(--g-paper-edge) 80%,transparent);color:var(--book-ink);vertical-align:top}.book-table tr:last-child td{border-bottom:0}.book-table td:first-child{font-weight:800}.book-ex{margin-top:.75rem;display:grid;gap:.2rem;font-size:.9375rem}.book-ex li:before{content:"→ ";color:var(--book-accent);font-weight:900}.book-watch{margin-top:.75rem;padding:.5rem .75rem;border-radius:.5rem;background:color-mix(in srgb,#e5484d 9%,var(--g-paper));border:1px solid color-mix(in srgb,#e5484d 35%,transparent);font-size:.875rem}.book-watch b{color:#b42318}.book-article{margin-top:.75rem;display:grid;gap:.6rem;font-size:.9375rem;line-height:1.7}@media (min-width:900px){.book-article[data-cols="2"]{display:block;column-count:2;column-gap:1.5rem}.book-article[data-cols="2"] p{margin-bottom:.6rem;break-inside:avoid}}.book-model{margin-top:.5rem;padding:.6rem .75rem;border-radius:.5rem;background:color-mix(in srgb,#fff 55%,var(--g-paper));border-inline-start:4px solid var(--book-accent);font-size:.875rem;font-style:italic}.book-check li{display:flex;gap:.5rem;padding:.2rem 0;font-size:.9375rem}.book-check li:before{content:"☐";color:var(--book-accent);font-weight:900}.book-questions{counter-reset:q;display:grid;gap:.35rem;margin-top:.5rem}.book-questions li{counter-increment:q;display:flex;gap:.5rem;font-size:.9375rem}.book-questions li:before{content:counter(q,upper-alpha);display:inline-grid;place-items:center;flex:none;width:1.4rem;height:1.4rem;border-radius:999px;background:var(--book-tint);color:var(--book-accent);font-weight:900;font-size:.75rem}.book-games{display:grid;gap:.75rem;padding:.75rem;border-radius:1rem;background:var(--surface-raised);border:2px solid var(--book-accent)}.book-games-h{display:flex;align-items:center;gap:.6rem}.book-board{position:absolute;inset:0;z-index:5;touch-action:none;cursor:crosshair}.book-board-tools{position:sticky;top:.5rem;z-index:6;display:flex;flex-wrap:wrap;justify-content:center;gap:.375rem;margin:0 auto .5rem;padding:.375rem;width:fit-content;border-radius:999px;background:var(--surface-raised);box-shadow:var(--g-shadow)}.book-swatch{width:2rem;height:2rem;border-radius:999px;border:3px solid var(--surface);box-shadow:0 0 0 1px color-mix(in srgb,var(--text-strong) 25%,transparent)}.book-swatch[aria-pressed=true]{box-shadow:0 0 0 3px var(--text-strong)}@media print{.book-bar,.book-board-tools,.book-edit,.book-ex-purpose,.book-ex-state,.book-finish,.book-hint,.book-listen,.book-play,.book-sheet,.book-tools{display:none!important}.book-stage{background:none;padding:0}.book-page{box-shadow:none;break-after:page}}.book-page[dir=rtl]{font-family:var(--font-body-ar),var(--font-sans)}.book-page .book-h{margin-top:.85rem;font-weight:900;font-size:1.25rem;line-height:1.2;color:var(--book-ink)}.book-page .book-subh{margin-top:1rem;font-weight:800;font-size:1rem;color:var(--book-accent)}.book-group-note{font-weight:700;letter-spacing:0;text-transform:none;color:var(--book-ink-soft)}.book-page .book-p{margin-top:.6rem;font-size:.9375rem;line-height:1.75;unicode-bidi:plaintext}.book-page .book-muted{color:var(--book-ink-soft);font-style:italic}.book-turn[data-side=c] .book-speaker{background:color-mix(in srgb,var(--book-ink) 75%,var(--book-a))}.book-turn[data-side=c] .book-line{background:color-mix(in srgb,var(--book-ink) 6%,var(--g-paper));border-color:color-mix(in srgb,var(--book-ink) 22%,transparent)}.book-pairs{margin-top:.5rem;border-radius:.6rem;border:1px solid color-mix(in srgb,var(--g-paper-edge) 90%,transparent)}.book-pairs .book-table td:not(:first-child){color:var(--book-ink-soft)}.book-page .book-term{display:grid;grid-template-columns:minmax(7rem,auto) 1fr;gap:.75rem;padding:.3rem 0;border-bottom:1px dotted color-mix(in srgb,var(--g-paper-edge) 90%,transparent);font-size:.9rem}.book-page .book-term:last-child{border-bottom:0}.book-term b{color:var(--book-accent)}.book-steps{margin-top:.5rem;display:grid;gap:.35rem;padding-inline-start:1.6rem;list-style:decimal;font-size:.9375rem}.book-steps li::marker{color:var(--book-accent);font-weight:900}.book-page[dir=rtl] .book-ex li:before{content:"← "}.book-chips{display:flex;flex-wrap:wrap;gap:.35rem;margin-top:.5rem}.book-chips li{padding:.2rem .6rem;border-radius:999px;background:color-mix(in srgb,#fff 55%,var(--g-paper));border:1px solid color-mix(in srgb,var(--book-accent) 30%,transparent);font-size:.875rem;font-weight:700;color:var(--book-ink)}.book-media .book-img{width:100%;height:auto;border-radius:.5rem;border:1px solid color-mix(in srgb,var(--g-paper-edge) 90%,transparent)}.book-video-ph{display:grid;place-items:center;gap:.5rem;aspect-ratio:16/9;border-radius:.5rem;background:#111;color:#fff;font-weight:800}.book-file{display:flex;align-items:center;gap:.6rem;margin-top:.75rem;padding:.6rem .75rem;border-radius:.6rem;background:color-mix(in srgb,#fff 55%,var(--g-paper));border:1px solid var(--book-rule)}.book-file,.book-file a{color:var(--book-ink)}.book-file-dl{display:inline-grid;place-items:center;width:2.25rem;height:2.25rem;border-radius:999px;background:var(--book-tint)}.book-sec-h{flex-wrap:wrap}.book-sec-end{gap:.35rem;margin-inline-start:auto;align-self:center}.book-sec-end,.book-tag{display:inline-flex;align-items:center}.book-tag{padding:.05rem .5rem;border-radius:999px;font-size:.6875rem;font-weight:800;letter-spacing:.02em;white-space:nowrap;color:var(--book-ink);background:color-mix(in srgb,var(--book-ink) 8%,var(--g-paper))}.book-tag[data-purpose=class]{color:#1f4f8f;background:color-mix(in srgb,#1f6fb2 14%,var(--g-paper))}.book-tag[data-purpose=review]{color:#7a4a00;background:color-mix(in srgb,#f5b04a 28%,var(--g-paper))}.book-edit{display:inline-grid;place-items:center;width:2rem;height:2rem;border-radius:999px;border:1px solid var(--book-rule);color:var(--book-ink)}.book-edit:hover{background:var(--book-tint)}.book-locked{display:grid;justify-items:center;gap:.4rem;margin-top:1rem;padding:2rem 1rem;border-radius:.75rem;border:2px dashed color-mix(in srgb,var(--book-ink) 18%,transparent);text-align:center;color:var(--book-ink-soft)}.book-exs{margin-top:1.1rem;padding-top:.75rem;border-top:2px solid var(--book-rule)}.book-page .book-exs-h{display:flex;align-items:center;gap:.4rem;font-size:.75rem;font-weight:900;letter-spacing:.1em;text-transform:uppercase;color:var(--book-accent)}.book-ex-list{display:grid;gap:.4rem;margin-top:.5rem}.book-ex-card{display:flex;align-items:center;gap:.6rem;width:100%;min-height:3rem;padding:.45rem .6rem;border-radius:.65rem;border:1px solid color-mix(in srgb,var(--book-accent) 28%,transparent);background:color-mix(in srgb,#fff 60%,var(--g-paper));text-align:start;color:var(--book-ink);transition:transform .12s ease,border-color .12s ease,background-color .12s ease}.book-ex-card:hover:not(:disabled){border-color:var(--book-accent);background:var(--book-tint)}.book-ex-card:active:not(:disabled){transform:scale(.99)}.book-ex-card[data-purpose=class]{border-inline-start:4px solid #1f6fb2}.book-ex-card[data-purpose=review]{border-inline-start:4px solid #e39a2d}.book-ex-no{display:inline-grid;place-items:center;flex:none;width:1.9rem;height:1.9rem;border-radius:.4rem;background:var(--book-accent);color:#fff;font-weight:900}.book-ex-main{display:flex;flex-wrap:wrap;align-items:center;gap:.25rem .5rem;min-width:0;flex:1}.book-ex-title{min-width:0;font-weight:800;font-size:.9rem;line-height:1.3}.book-ex-state{display:inline-grid;place-items:center;flex:none;min-width:2rem;height:2rem;padding:0 .4rem;border-radius:999px;background:var(--book-accent);color:#fff;font-size:.75rem;letter-spacing:-.05em}.book-ex-state[data-done]{background:#2e9b4f}.book-ex-purpose{display:flex;flex-wrap:wrap;gap:.25rem;margin:.3rem 0 .2rem;padding-inline-start:2.5rem}.book-ex-purpose button{min-height:2rem;padding:0 .6rem;border-radius:999px;border:1px solid color-mix(in srgb,var(--book-ink) 20%,transparent);font-size:.75rem;font-weight:800;color:var(--book-ink);background:var(--g-paper)}.book-ex-purpose button[aria-checked=true]{background:var(--book-ink);color:var(--g-paper)}.book-finish{margin-top:1rem}.book-finish button{display:inline-flex;align-items:center;gap:.4rem;min-height:2.75rem;padding:0 1rem;border-radius:999px;background:var(--book-accent);color:#fff;font-weight:800}.book-finish button:disabled{opacity:.55}.book-page .book-finish p{color:#2e7a45}.book-hint{padding:.5rem .75rem;border-radius:.75rem;background:var(--surface-raised);border:1px dashed color-mix(in srgb,var(--text-strong) 25%,transparent);font-size:.875rem;font-weight:600}.book-review{background:radial-gradient(circle at 100% 0,color-mix(in srgb,#f5b04a 22%,transparent),transparent 45%),var(--g-paper)}.book-todo{display:grid;gap:.3rem;margin-top:.5rem}.book-todo button{display:flex;align-items:center;gap:.6rem;width:100%;min-height:2.5rem;padding:.3rem .6rem;border-radius:.5rem;text-align:start;font-weight:700;font-size:.875rem;color:var(--book-ink);background:color-mix(in srgb,#fff 50%,var(--g-paper))}.book-todo button:hover{background:var(--book-tint)}.book-sheet{position:fixed;inset:0;z-index:60;display:grid;padding:0;background:rgb(10 10 14/.55);backdrop-filter:blur(3px)}.book-sheet-panel{display:flex;flex-direction:column;min-height:0;width:100%;max-width:72rem;margin:0 auto;background:var(--surface);overflow:hidden}@media (min-width:768px){.book-sheet{padding:2.5vh 1rem}.book-sheet-panel{border-radius:1rem;border:3px solid var(--book-accent);box-shadow:0 30px 80px rgb(0 0 0/.35)}}.book-sheet-h{display:flex;align-items:center;gap:.75rem;padding:.6rem .75rem;border-bottom:1px solid color-mix(in srgb,var(--text-strong) 10%,transparent);background:var(--surface-raised)}.book-sheet-b{flex:1;min-height:0;overflow:auto;overscroll-behavior:contain;padding:1rem}@media (min-width:768px){.book-sheet-b{padding:1.25rem 1.5rem 2rem}}.book-tools{position:fixed;inset-block-end:1rem;inset-inline-end:1rem;z-index:65;width:min(24rem,calc(100vw - 2rem));border-radius:1rem;background:var(--surface-raised);border:1px solid color-mix(in srgb,var(--text-strong) 14%,transparent);box-shadow:0 20px 60px rgb(0 0 0/.3);color:var(--text-strong)}.book-tools-h{display:flex;align-items:center;gap:.25rem;padding:.4rem;border-bottom:1px solid color-mix(in srgb,var(--text-strong) 10%,transparent)}.book-tools-tab{display:inline-flex;flex:1;align-items:center;justify-content:center;gap:.3rem;min-height:2.5rem;padding:0 .4rem;border-radius:.6rem;font-size:.8rem;font-weight:800;color:var(--text-muted)}.book-tools-tab[aria-selected=true]{background:var(--text-strong);color:var(--surface)}.book-tools-x{display:inline-grid;place-items:center;width:2.5rem;height:2.5rem;border-radius:.6rem}.book-tools-x:hover{background:var(--surface-hover)}.book-tools-b{display:grid;gap:.75rem;padding:.9rem}.book-tools-big{text-align:center;font-family:var(--font-display,inherit);font-weight:900;font-size:clamp(2.75rem,2rem + 3vw,4rem);line-height:1.05;overflow-wrap:anywhere}.book-tools-big[data-alarm]{color:#c8203a;font-size:clamp(1.75rem,1.4rem + 2vw,2.5rem);animation:book-alarm .6s ease-in-out 4}.book-tools-big[data-rolling]{opacity:.6}@keyframes book-alarm{50%{transform:scale(1.08)}}.book-tools-bar{height:.4rem;border-radius:999px;background:linear-gradient(90deg,var(--book-accent) var(--p,100%),color-mix(in srgb,var(--text-strong) 10%,transparent) 0)}.book-chip{min-width:2.75rem;min-height:2.5rem;padding:0 .6rem;border-radius:999px;border:1px solid color-mix(in srgb,var(--text-strong) 18%,transparent);font-weight:800}.book-chip[aria-pressed=true]{background:var(--text-strong);color:var(--surface)}.book-tool-main{background:var(--book-accent);border-color:transparent;color:#fff}.book-tool-main:disabled{opacity:.5}.book-teams{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:.5rem}.book-team{display:grid;gap:.25rem;padding:.6rem .4rem;border-radius:.75rem;text-align:center;background:color-mix(in srgb,var(--team) 12%,var(--surface));border:2px solid color-mix(in srgb,var(--team) 60%,transparent)}.book-team-name{font-weight:800;font-size:.85rem;color:var(--team)}.book-team-score{font-family:var(--font-display,inherit);font-weight:900;font-size:2.5rem;line-height:1}@media (prefers-reduced-motion:reduce){.book-tools-big[data-alarm]{animation:none}.book-ex-card{transition:none}}.book-page.book-page-plain{min-height:0;padding-bottom:1.25rem}.book-page-plain>:first-child{margin-top:0}:root{--bk-wood-top:#caa776;--bk-wood:#9f7949;--bk-wood-shadow:rgb(70 44 16/0.32)}@media (prefers-color-scheme:dark){:root:not([data-theme=light]){--bk-wood-top:#4b3b2b;--bk-wood:#30261c;--bk-wood-shadow:rgb(0 0 0/0.55)}}:root[data-theme=dark]{--bk-wood-top:#4b3b2b;--bk-wood:#30261c;--bk-wood-shadow:rgb(0 0 0/0.55)}.bk-room,.bk-shelf{--bk-paper:color-mix(in oklab,var(--surface-raised) 93%,#d6b27a);--bk-edge:color-mix(in oklab,var(--bk-paper) 78%,#7a5a32);--bk-page-h:clamp(30rem,72vh,46rem)}.bk-shelf{display:grid;grid-template-columns:repeat(auto-fill,minmax(9.25rem,1fr));gap:2.25rem 1.25rem;padding:.5rem .75rem 0;list-style:none}@media (min-width:640px){.bk-shelf{grid-template-columns:repeat(auto-fill,minmax(10.75rem,1fr));gap:2.75rem 1.75rem}}.bk-shelf>li{position:relative;display:flex;padding-bottom:.85rem}.bk-shelf>li:after{content:"";position:absolute;inset-inline:-.65rem;bottom:0;height:.8rem;background:linear-gradient(var(--bk-wood-top),var(--bk-wood));box-shadow:0 12px 16px -10px var(--bk-wood-shadow)}@media (min-width:640px){.bk-shelf>li:after{inset-inline:-.9rem}}.bk-cover{--bk-c1:#9b1f57;--bk-c2:#5e1135;position:relative;z-index:1;display:flex;flex-direction:column;gap:.2rem;width:100%;aspect-ratio:3/4;padding-block:.9rem;padding-inline:1.35rem .9rem;border-start-start-radius:3px;border-end-start-radius:3px;border-start-end-radius:10px;border-end-end-radius:10px;color:#fff;text-align:start;text-decoration:none;background:radial-gradient(120% 80% at 90% 0,rgb(255 255 255/.08),transparent 55%),linear-gradient(155deg,var(--bk-c1),var(--bk-c2));box-shadow:inset 0 1px 0 rgb(255 255 255/.12),0 2px 3px rgb(0 0 0/.22),0 16px 22px -14px rgb(0 0 0/.6);transform-origin:50% 100%;transition:transform var(--mo-4) var(--ez-out-expo)}.bk-cover[data-tone="1"]{--bk-c1:#4338ca;--bk-c2:#23206b}.bk-cover[data-tone="2"]{--bk-c1:#0d6c65;--bk-c2:#0a403c}.bk-cover[data-tone="3"]{--bk-c1:#8c4c10;--bk-c2:#5a2f08}.bk-cover[data-tone="4"]{--bk-c1:#356b1e;--bk-c2:#1e4411}.bk-cover[data-tone="5"]{--bk-c1:#1d5a8c;--bk-c2:#10324f}.bk-cover:before{content:"";position:absolute;inset-block:0;inset-inline-start:0;width:.6rem;border-start-start-radius:inherit;border-end-start-radius:inherit;background:linear-gradient(90deg,rgb(0 0 0/.3),rgb(0 0 0/.08) 65%,rgb(255 255 255/.14))}:where([dir=rtl]) .bk-cover:before{background:linear-gradient(270deg,rgb(0 0 0/.3),rgb(0 0 0/.08) 65%,rgb(255 255 255/.14))}a.bk-cover:hover,button.bk-cover:hover{transform:translateY(-6px) rotate(-1.2deg)}:where([dir=rtl]) a.bk-cover:hover,:where([dir=rtl]) button.bk-cover:hover{transform:translateY(-6px) rotate(1.2deg)}.bk-cover:focus-visible{outline:3px solid var(--text-strong);outline-offset:3px}.bk-cover-label{font-size:.8125rem;font-weight:700;letter-spacing:.06em;text-transform:uppercase}.bk-cover-no{margin-top:.2rem;font-family:var(--font-display);font-size:2.1rem;font-weight:800;line-height:1}.bk-cover-title{margin-top:.35rem;font-size:1.02rem;font-weight:800;line-height:1.35;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden;overflow-wrap:anywhere}@media (min-width:640px){.bk-cover-no{font-size:2.6rem}.bk-cover-title{-webkit-line-clamp:4}}.bk-cover-meta{margin-top:auto;display:flex;flex-direction:column;gap:.1rem;font-size:.8125rem;font-weight:600;line-height:1.45}.bk-cover-flag{align-self:flex-start;margin-top:.35rem;padding:0 .55rem;border:1px solid rgb(255 255 255/.75);border-radius:999px}.bk-cover-new{align-items:center;justify-content:center;padding-inline:.9rem;text-align:center;color:var(--text-strong);background:var(--surface-raised);border:2px dashed var(--field-border);box-shadow:none;cursor:pointer}.bk-cover-new:before{display:none}.bk-cover-form{aspect-ratio:auto;min-height:100%;justify-content:space-between;gap:.75rem;cursor:default}.bk-cover-plus{display:grid;place-items:center;width:3rem;height:3rem;margin-bottom:.35rem;border-radius:999px;background:var(--surface-sunken)}.bk-room{display:flex;flex-direction:column;gap:1rem}.bk-desk{display:flex;align-items:stretch;justify-content:center;gap:.75rem;touch-action:pan-y pinch-zoom}.bk-spread{flex:1;min-width:0;display:grid;grid-template-columns:minmax(0,1fr);perspective:2200px}.bk-spread-wide{grid-template-columns:repeat(2,minmax(0,1fr));max-width:74rem}.bk-slot-1{grid-column:1}.bk-slot-2{grid-column:2}.bk-leaf{position:relative;min-width:0;display:flex}.bk-leaf>*{flex:1;min-width:0}.bk-spine-left{transform-origin:left center}.bk-spine-right{transform-origin:right center}.bk-paper{position:relative;display:flex;flex-direction:column;min-height:var(--bk-page-h);padding:1rem 1.15rem 3rem;color:var(--text-strong);background-color:var(--bk-paper);border:1px solid var(--border-soft);border-radius:6px}@media (min-width:640px){.bk-paper{padding:1.4rem 2rem 3.25rem}}.bk-spine-left>.bk-paper{border-top-left-radius:2px;border-bottom-left-radius:2px;background-image:linear-gradient(90deg,rgb(0 0 0/.09),transparent 2.25rem);box-shadow:1px 0 0 var(--bk-edge),3px 1px 0 var(--bk-paper),4px 1px 0 var(--bk-edge),6px 2px 0 var(--bk-paper),7px 2px 0 var(--bk-edge),0 22px 36px -22px rgb(0 0 0/.45)}.bk-spine-right>.bk-paper{border-top-right-radius:2px;border-bottom-right-radius:2px;background-image:linear-gradient(270deg,rgb(0 0 0/.09),transparent 2.25rem);box-shadow:-1px 0 0 var(--bk-edge),-3px 1px 0 var(--bk-paper),-4px 1px 0 var(--bk-edge),-6px 2px 0 var(--bk-paper),-7px 2px 0 var(--bk-edge),0 22px 36px -22px rgb(0 0 0/.45)}.bk-paper-blank{border:2px dashed var(--field-border);background-image:repeating-linear-gradient(to bottom,transparent 0 1.95rem,var(--border-soft) 1.95rem 2rem)}.bk-head{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:.25rem .5rem;min-height:2.75rem;margin-bottom:.75rem;padding-bottom:.4rem;border-bottom:1px solid var(--border-soft)}.bk-running{flex:1 1 8rem;font-size:.8125rem;font-weight:600;color:var(--text-muted)}.bk-tools{display:flex;flex-wrap:wrap;align-items:center;justify-content:flex-end;gap:.125rem;margin-inline-start:auto}.bk-body{flex:1;min-width:0}.bk-folio{position:absolute;bottom:.9rem;inset-inline:1.25rem;font-size:.8125rem;font-weight:600;color:var(--text-muted);text-align:center}.bk-spine-left .bk-folio{text-align:right}.bk-spine-right .bk-folio{text-align:left}.bk-title{font-family:var(--font-display);font-size:1.35rem;font-weight:800;line-height:1.3;overflow-wrap:anywhere}.bk-kind{display:inline-flex;align-items:center;gap:.4rem;font-size:.8125rem;font-weight:700;color:var(--text-muted)}.bk-prose{font-size:1.0625rem;line-height:1.95}.bk-cover-page{aspect-ratio:auto;min-height:var(--bk-page-h);padding-block:2rem;padding-inline:2.4rem 1.75rem;gap:.35rem}.bk-cover-page .bk-cover-label{font-size:.875rem}.bk-cover-page .bk-cover-no{font-size:clamp(4.5rem,12vw,7rem);margin-top:1.5rem}.bk-cover-page .bk-cover-title{font-family:var(--font-display);font-size:clamp(1.6rem,4vw,2.4rem);line-height:1.25;-webkit-line-clamp:5}.bk-cover-desc{max-width:32rem;margin-top:.5rem;font-size:1.02rem;line-height:1.7}.bk-cover-page .bk-cover-meta{flex-direction:row;flex-wrap:wrap;gap:.4rem}.bk-cover-page .bk-cover-meta>span{padding:.1rem .65rem;border:1px solid rgb(255 255 255/.45);border-radius:999px}.bk-cover-tools{position:absolute;top:1rem;inset-inline-end:1rem;z-index:1}.bk-toc-row{border-bottom:1px dashed var(--border-soft)}.bk-toc-link{display:flex;flex:1;align-items:center;gap:.75rem;min-width:0;min-height:3.4rem;padding:.4rem .35rem;border-radius:var(--radius-control);text-align:start}.bk-toc-link:hover{background:var(--surface-hover)}.bk-toc-no{display:grid;flex-shrink:0;place-items:center;width:2rem;height:2rem;border-radius:999px;background:var(--surface-sunken);font-weight:800}.bk-toc-done{background:var(--success-tint,var(--surface-sunken));color:var(--success)}.bk-toc-locked{color:var(--text-muted)}.bk-toc-title{display:block;overflow:hidden;font-weight:700;white-space:nowrap;text-overflow:ellipsis}.bk-toc-dots{display:none;flex:0 1 3rem;min-width:.75rem;align-self:flex-end;margin-bottom:.7rem;border-bottom:2px dotted var(--field-border)}@media (min-width:640px){.bk-toc-dots{display:block}}.bk-toc-page{font-size:.8125rem;font-weight:600;white-space:nowrap;color:var(--text-muted)}.bk-toc-tools{padding:.25rem .35rem .85rem}.bk-new-lesson{display:flex;flex-wrap:wrap;align-items:flex-end;gap:.5rem;padding:.9rem;border:1.5px dashed var(--field-border);border-radius:var(--radius-card)}.bk-new-lesson>label{flex:1 1 12rem}.bk-chapter{display:flex;flex-direction:column;align-items:flex-start;padding-top:clamp(.5rem,6vh,3.5rem)}.bk-chapter-label{font-size:.875rem;font-weight:800;letter-spacing:.04em;color:var(--text-muted)}.bk-chapter-no{font-family:var(--font-display);font-size:clamp(4rem,11vw,6.5rem);font-weight:900;line-height:1;color:color-mix(in oklab,var(--text-strong) 22%,transparent)}.bk-chapter-title{margin-top:.75rem;font-family:var(--font-display);font-size:clamp(1.6rem,4vw,2.2rem);font-weight:800;line-height:1.25;overflow-wrap:anywhere}.bk-chapter-summary{margin-top:.5rem;font-size:1.05rem;line-height:1.7}.bk-chapter-meta{display:flex;flex-wrap:wrap;gap:.4rem;margin-top:1rem}.bk-chapter-meta>span{padding:.15rem .65rem;border:1px solid var(--border-strong);border-radius:999px;font-size:.8125rem;font-weight:600;color:var(--text-muted)}.bk-video{place-items:center;aspect-ratio:16/9;overflow:hidden;border-radius:var(--radius-card);background:linear-gradient(135deg,#241d27,#0d0b0f)}.bk-video,.bk-video-play{position:relative;display:grid}.bk-video-play{z-index:1;place-items:center;width:3.5rem;height:3.5rem;border-radius:999px;background:rgb(255 255 255/.92);color:#141014}.bk-video-host{position:absolute;z-index:1;bottom:.5rem;inset-inline-start:.5rem;padding:.1rem .55rem;border-radius:999px;background:rgb(0 0 0/.62);color:#fff;font-size:.8125rem}.bk-stop{display:inline-flex;align-items:center;gap:.4rem;min-height:2.75rem;padding:.25rem .8rem;border-radius:6px;background:#fde68a;color:#3d2c00;font-size:.875rem;font-weight:700;box-shadow:0 2px 0 rgb(0 0 0/.1);transform:rotate(-1deg);transition:transform var(--mo-3) var(--ez-out-expo)}.bk-stop:hover{transform:rotate(0deg) translateY(-1px)}.bk-doc{display:flex;flex-wrap:wrap;align-items:center;gap:.75rem;padding:1rem;border:1px solid var(--border-soft);border-radius:var(--radius-card);background:var(--surface-raised)}.bk-doc-icon{display:grid;flex-shrink:0;place-items:center;width:3rem;height:3rem;border-radius:.8rem;background:var(--surface-sunken)}.bk-game{margin-top:1.25rem;padding:1.25rem;border:1px solid var(--border-soft);border-radius:var(--radius-card);background:var(--surface-raised)}.bk-game-icon{width:3.5rem;height:3.5rem;border-radius:1rem}.bk-state{display:inline-flex;align-items:center;gap:.4rem;margin-top:.85rem;font-size:.875rem;font-weight:700}.bk-state-ok{color:var(--success)}.bk-state-warn{color:var(--warning)}.bk-live.bk-live-student{margin-top:.75rem;padding:0;border:0;background:transparent}.bk-live{margin-top:1rem;padding:.75rem;border:1px solid var(--border-soft);border-radius:var(--radius-card)}.bk-choice,.bk-live{background:var(--surface-raised)}.bk-choice{display:flex;flex-direction:column;align-items:flex-start;gap:.3rem;min-height:9rem;padding:1.1rem;border:1px solid var(--field-border);border-radius:var(--radius-card);text-align:start;transition:transform var(--mo-3) var(--ez-out-expo)}.bk-choice:hover{transform:translateY(-2px)}.bk-choice-wide{flex-direction:row;align-items:center;gap:.85rem;min-height:0}.bk-choice-wide .bk-choice-icon{margin-bottom:0;flex-shrink:0}.bk-choice-icon{display:grid;place-items:center;width:3rem;height:3rem;margin-bottom:.35rem;border-radius:.9rem;background:var(--surface-sunken)}.bk-kind-tile{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:.4rem;width:100%;min-height:4.5rem;padding:.75rem;border:1px solid var(--field-border);border-radius:var(--radius-control);background:var(--surface-raised);font-size:.875rem;font-weight:700}.bk-kind-tile:hover{border-color:var(--text-strong)}.bk-end{display:flex;flex-direction:column;align-items:center;padding-top:clamp(.5rem,5vh,2.5rem);text-align:center}.bk-end-mark.bk-end-done{background:var(--success-tint,var(--surface-sunken));color:var(--success)}.bk-end-mark{display:grid;place-items:center;width:4rem;height:4rem;border-radius:999px;background:var(--surface-sunken)}.bk-edge{display:grid;flex-shrink:0;align-self:center;place-items:center;width:3rem;height:3rem;border:1px solid var(--field-border);border-radius:999px;background:var(--surface-raised);color:var(--text-strong);box-shadow:var(--shadow-card);transition:transform var(--mo-3) var(--ez-out-expo)}.bk-edge:hover:not(:disabled){transform:scale(1.06)}.bk-edge:disabled{opacity:.35;cursor:not-allowed}.bk-pager{position:sticky;bottom:max(.75rem,env(safe-area-inset-bottom),calc(var(--bn-nav, 0px) + var(--bn-dock, 0px)));z-index:10;display:flex;align-items:center;gap:.35rem;width:100%;max-width:74rem;margin-inline:auto;padding:.4rem;border:1px solid var(--border-soft);border-radius:var(--radius-card);background:var(--surface-raised);box-shadow:var(--shadow-overlay)}.bk-pager-step{display:grid;flex-shrink:0;place-items:center;width:2.75rem;height:2.75rem;border-radius:999px;color:var(--text-strong)}.bk-pager-step:hover:not(:disabled){background:var(--surface-hover)}.bk-pager-step:disabled{opacity:.35;cursor:not-allowed}.bk-chips{display:flex;gap:.35rem;padding:.15rem;overflow-x:auto;list-style:none;scrollbar-width:none}.bk-chips::-webkit-scrollbar{display:none}.bk-chip{display:inline-flex;align-items:center;gap:.4rem;max-width:15rem;min-height:2.75rem;padding:0 .85rem;border:1px solid var(--border-soft);border-radius:999px;font-size:.875rem;font-weight:600;white-space:nowrap;color:var(--text-muted)}.bk-chip:hover{color:var(--text-strong)}.bk-chip[aria-current=true]{border-color:transparent;background:var(--action-face);color:var(--action-ink)}.bk-chip-no{display:grid;place-items:center;min-width:1.45rem;height:1.45rem;padding-inline:.2rem;border-radius:999px;background:var(--surface-sunken);color:var(--text-strong);font-size:.8125rem;font-weight:800}.bk-chip[aria-current=true] .bk-chip-no{background:rgb(255 255 255/.22);color:inherit}.bk-sheet{width:100vw;max-width:none;height:100dvh;max-height:none;border-radius:0}.bk-sheet>div{height:100%}@media (min-width:640px){.bk-sheet{width:min(calc(100vw - 2rem),76rem);height:min(calc(100dvh - 2rem),60rem);border-radius:var(--radius-panel)}}.bk-leaf[data-turn]{z-index:2;backface-visibility:hidden;will-change:transform}.bk-leaf[data-turn=out]{animation:bk-fold-out var(--mo-4) var(--ez-in) both}.bk-leaf[data-turn=in]{animation:bk-fold-in var(--mo-5) var(--ez-out-expo) both}.bk-leaf[data-turn=settle]{animation:bk-settle var(--mo-5) var(--ez-out-expo) both}.bk-leaf[data-turn]:after{content:"";position:absolute;inset:0;border-radius:6px;background:rgb(0 0 0/.2);pointer-events:none}.bk-leaf[data-turn=out]:after{animation:bk-shade-on var(--mo-4) var(--ez-in) both}.bk-leaf[data-turn=in]:after,.bk-leaf[data-turn=settle]:after{animation:bk-shade-off var(--mo-5) var(--ez-out-expo) both}@keyframes bk-fold-out{0%{transform:rotateY(0deg)}to{transform:rotateY(var(--bk-lift))}}@keyframes bk-fold-in{0%{transform:rotateY(var(--bk-lift))}to{transform:rotateY(0deg)}}@keyframes bk-settle{0%{transform:scale(.985)}to{transform:none}}@keyframes bk-shade-on{0%{opacity:0}to{opacity:1}}@keyframes bk-shade-off{0%{opacity:1}to{opacity:0}}@media (prefers-reduced-motion:reduce){.bk-leaf[data-turn],.bk-leaf[data-turn]:after{animation:none}.bk-leaf[data-turn]:after{display:none}.bk-choice,.bk-cover,.bk-edge,.bk-stop{transition:none}:where([dir=rtl]) a.bk-cover:hover,:where([dir=rtl]) button.bk-cover:hover,a.bk-cover:hover,button.bk-cover:hover{transform:none}}.bk-bar{position:relative;z-index:12;display:flex;align-items:center;gap:.25rem;min-height:3.25rem;padding:.375rem .5rem;border-radius:var(--radius-panel)}.bk-bar-btn{display:inline-flex;flex-shrink:0;align-items:center;justify-content:center;gap:.375rem;min-width:2.75rem;min-height:2.75rem;padding:0 .5rem;border-radius:var(--radius-control);font-size:.875rem;font-weight:700;color:var(--text-strong);transition:background-color var(--mo-2) var(--ez-out)}.bk-bar-btn:hover{background:var(--surface-hover)}.bk-bar-btn[aria-pressed=true]{background:var(--action-face);color:var(--action-ink)}.bk-bar-btn:disabled{opacity:.4;cursor:not-allowed}.bk-bar-btn-wide{padding-inline:.75rem}.bk-bar-label{display:none}@media (min-width:640px){.bk-bar-label{display:inline}}.bk-bar-badge{display:inline-grid;place-items:center;min-width:2.75rem;height:1.35rem;padding-inline:.35rem;border-radius:999px;background:var(--action-face);color:var(--action-ink);font-size:.75rem;font-weight:800}.bk-bar-btn[aria-pressed=true] .bk-bar-badge{background:rgb(255 255 255/.22);color:inherit}.bk-bar-where{display:flex;flex:1;flex-direction:column;align-items:flex-start;min-width:0;min-height:2.75rem;padding:.2rem .5rem;border-radius:var(--radius-control);text-align:start;transition:background-color var(--mo-2) var(--ez-out)}.bk-bar-where:hover{background:var(--surface-hover)}.bk-bar-eyebrow,.bk-bar-title{display:block;max-width:100%;overflow:hidden;white-space:nowrap;text-overflow:ellipsis}.bk-bar-eyebrow{font-size:.75rem;font-weight:600;color:var(--text-muted)}.bk-bar-title{font-family:var(--font-display);font-size:1rem;font-weight:800;line-height:1.25;color:var(--text-strong)}.bk-bar-tools{display:flex;flex-shrink:0;align-items:center;gap:.125rem}.bk-bar-progress{position:absolute;inset-inline:.75rem;bottom:0;height:2px;border-radius:2px;background:linear-gradient(to right,var(--action-face) var(--p),var(--border-soft) var(--p))}:where([dir=rtl]) .bk-bar-progress{background:linear-gradient(to left,var(--action-face) var(--p),var(--border-soft) var(--p))}.bk-mode{display:inline-flex;flex-shrink:0;gap:.125rem;padding:3px;border-radius:var(--radius-lg);background:var(--surface-sunken)}.bk-mode [role=radio]{display:inline-flex;align-items:center;gap:.35rem;min-height:2.5rem;padding:0 .7rem;border-radius:var(--radius-md);font-size:.875rem;font-weight:700;color:var(--text-muted)}.bk-mode [role=radio]:hover{color:var(--text-strong)}.bk-mode [role=radio][aria-checked=true]{background:var(--surface-raised);color:var(--text-strong);box-shadow:var(--shadow-card)}.bk-mode [role=radio]:disabled{opacity:.5;cursor:not-allowed}@media (max-width:767px){.bk-mode [role=radio]>span{display:none}.bk-mode [role=radio]{padding:0 .6rem}}@media (max-width:639px){.bk-bar-tools>[data-overflow],.bk-mode{display:none}.bk-bar{gap:.125rem;padding-inline:.25rem}}@media (min-width:640px){.bk-menu-only{display:none}}.bk-drawer{width:min(26rem,92vw);height:100dvh;max-height:100dvh;margin:0;margin-inline-end:auto;padding:0;border:0;border-inline-end:1px solid var(--border-soft);background:var(--surface-overlay);color:var(--text-strong);box-shadow:var(--shadow-overlay)}.bk-drawer-in{display:flex;flex-direction:column;height:100%}.bk-drawer-h{display:flex;align-items:flex-start;gap:.5rem;padding:max(1rem,env(safe-area-inset-top)) 1rem .75rem;border-bottom:1px solid var(--border-soft)}.bk-drawer-b{flex:1;min-height:0;padding:.5rem;overflow-y:auto;overscroll-behavior:contain}.bk-drawer-f{padding:.5rem .5rem max(.75rem,env(safe-area-inset-bottom));border-top:1px solid var(--border-soft)}.bk-drawer-list{margin:0;padding:0;list-style:none}.bk-drawer-row{display:flex;align-items:center;gap:.6rem;width:100%;min-height:2.75rem;padding:.3rem .6rem;border-inline-start:3px solid transparent;border-radius:var(--radius-control);font-size:.9375rem;font-weight:600;text-align:start;color:var(--text-strong);transition:background-color var(--mo-2) var(--ez-out)}.bk-drawer-row:hover:not(:disabled){background:var(--surface-hover)}.bk-drawer-row[aria-current=page]{background:var(--surface-hover);border-color:var(--action-face)}.bk-drawer-row:disabled{opacity:.5;cursor:not-allowed}.bk-drawer-page{padding-inline-start:1.6rem;font-weight:500}.bk-drawer-lesson{position:sticky;top:0;z-index:1;background:var(--surface-overlay)}.bk-drawer-lesson .bk-drawer-row{font-weight:800}.bk-drawer-kind,.bk-drawer-no{flex-shrink:0;color:var(--text-muted)}.bk-drawer-no{margin-inline-start:auto;font-size:.8125rem}.bk-drawer-done{color:var(--success)}.bk-drawer-resume{display:block;width:100%;margin-bottom:.5rem;padding:.6rem .75rem;border:1px dashed var(--field-border);border-radius:var(--radius-card);text-align:start}.bk-drawer-resume:hover:not(:disabled){background:var(--surface-hover)}.bk-drawer-units{margin-top:.5rem;border-top:1px solid var(--border-soft)}.bk-progress{height:.35rem;border-radius:999px;background:var(--surface-sunken)}.bk-progress>i{display:block;height:100%;width:var(--p,0);border-radius:inherit;background:var(--action-face)}.bk-review-in{display:flex;flex-direction:column;height:100%}.bk-review-h{display:flex;align-items:center;gap:.75rem;padding:.75rem var(--space-card,1.25rem);border-bottom:1px solid var(--border-soft)}.bk-review-tabs{display:flex;gap:.125rem;margin:.75rem auto 0;padding:3px;border-radius:var(--radius-lg);background:var(--surface-sunken)}.bk-review-tabs [role=tab]{min-height:2.5rem;padding:0 1rem;border-radius:var(--radius-md);font-size:.875rem;font-weight:700;color:var(--text-muted)}.bk-review-tabs [role=tab][aria-selected=true]{background:var(--surface-raised);color:var(--text-strong);box-shadow:var(--shadow-card)}.bk-review-b{flex:1;min-height:0;padding:var(--space-card,1.25rem);overflow-y:auto;overscroll-behavior:contain}.bk-desk{position:relative}.bk-ink{position:absolute;inset:0;z-index:5}.bk-desk-wide>.bk-ink{inset-inline:3.75rem}.bk-ink .book-board-tools{position:absolute;top:.5rem;inset-inline-start:50%;z-index:6;margin:0;translate:-50% 0;border:1px solid var(--border-soft);background:var(--surface-overlay);box-shadow:var(--shadow-overlay)}:where([dir=rtl]) .bk-ink .book-board-tools{translate:50% 0}.bk-dock{display:contents}.bk-dock[hidden]{display:none}.bk-room .book-tools{inset-block-end:max(.75rem,env(safe-area-inset-bottom),var(--bn-nav,0px));border:1px solid var(--border-soft);border-radius:var(--radius-panel);background:var(--surface-overlay);box-shadow:var(--shadow-overlay)}.bk-purpose{display:inline-flex;flex-wrap:wrap;gap:.125rem;margin-top:.75rem;padding:3px;border-radius:999px;background:var(--surface-sunken)}.bk-purpose [role=radio]{min-height:2.25rem;padding:0 .75rem;border-radius:999px;font-size:.8125rem;font-weight:700;color:var(--text-muted)}.bk-purpose [role=radio][aria-checked=true]{background:var(--action-face);color:var(--action-ink)}.bk-purpose [role=radio]:disabled{opacity:.5}.bk-room[data-view=teach] :is(.bk-tools,.bk-cover-tools,.bk-new-lesson,.bk-toc-tools,.bk-build,.bk-purpose){display:none}.bk-room[data-view=teach]{--bk-page-h:clamp(32rem,78vh,54rem)}.bk-room[data-view=teach] .bk-spread-wide{max-width:84rem}.bk-host:fullscreen{overflow:auto;padding:.75rem clamp(.75rem,3vw,2.5rem) 1rem;background:var(--surface);--bn-nav:0px}.bk-host:fullscreen .bk-bar{position:sticky;top:0}.bk-host:fullscreen .bk-spread-wide{max-width:none}@media print{.bk-bar,.bk-dock,.bk-drawer,.bk-edge,.bk-ink,.bk-pager,.bk-purpose,.bk-review{display:none!important}}@media (prefers-reduced-motion:reduce){.bk-bar-btn,.bk-bar-where,.bk-drawer-row{transition:none}}.bk-purpose [role=radio]{min-height:2.75rem}.bk-teach-games{display:flex;flex-wrap:wrap;gap:.5rem;margin:0;padding:0;list-style:none}.bk-teach-tag{flex-shrink:0;padding:.1rem .5rem;border-radius:999px;background:var(--surface-sunken);color:var(--text-muted);font-size:.75rem;font-weight:700}.bk-review-card{display:flex;align-items:flex-start;gap:.85rem;padding:1rem 1.1rem;border:1px solid var(--border-soft);border-radius:var(--radius-card);background:var(--bk-paper,var(--surface-raised))}.bk-review-mark{display:grid;flex:none;place-items:center;width:2.75rem;height:2.75rem;border-radius:999px;background:var(--success-tint,var(--surface-sunken));color:var(--success)}.bk-review-empty{padding:1.5rem 1rem;border:1px dashed var(--field-border);border-radius:var(--radius-card);text-align:center;font-size:.9375rem;font-weight:600;color:var(--text-muted)}.bk-review-card+.bk-live,.bk-review-card+.bk-review-empty{margin-top:1rem}.bk-review-go{display:flex;flex-wrap:wrap;gap:.5rem;margin-top:.85rem}.bk-games-group+.bk-games-group{margin-top:1.5rem}.bk-games-h{display:flex;align-items:center;gap:.5rem;margin-bottom:.5rem;font-size:.875rem;font-weight:800;color:var(--text-strong)}.bk-games-list{display:flex;flex-direction:column;gap:.4rem}.bk-game-row{display:flex;align-items:center;gap:.75rem;width:100%;min-height:3.25rem;padding:.5rem .85rem;border:1px solid var(--border-soft);border-radius:var(--radius-card);background:var(--bk-paper,var(--surface-raised));color:var(--text-strong);font-size:.9375rem;text-align:start}.bk-game-row:hover{border-color:var(--text-strong);background:var(--surface-hover)}.bk-game-row:focus-visible{outline:2px solid var(--action-face);outline-offset:2px}.bk-game-icon{display:grid;flex:none;place-items:center;width:2.25rem;height:2.25rem;border-radius:var(--radius-control);background:var(--surface-sunken)}.bk-game-meta{display:block;overflow:hidden;font-size:.75rem;font-weight:600;color:var(--text-muted);text-overflow:ellipsis;white-space:nowrap}.bk-game-open{display:inline-flex;flex:none;align-items:center;gap:.2rem;font-size:.8125rem;font-weight:700;color:var(--text-muted)}.bk-cards{gap:1rem}.bk-cards,.bk-deck{display:flex;flex-direction:column}.bk-deck{align-items:center;gap:.85rem}.bk-card-wrap{position:relative;width:min(100%,32rem);margin-inline:auto}.bk-card{display:block;width:100%;height:clamp(13rem,42vh,19rem);perspective:1400px;border-radius:var(--radius-card);color:var(--text-strong);text-align:center;cursor:pointer;-webkit-tap-highlight-color:transparent}.bk-card:focus-visible{outline:2px solid var(--action-face);outline-offset:4px}.bk-card-inner{position:relative;display:block;width:100%;height:100%;transform-style:preserve-3d;transition:transform var(--mo-5) var(--ez-out-expo)}.bk-card[aria-pressed=true] .bk-card-inner{transform:rotateY(180deg)}[dir=rtl] .bk-card[aria-pressed=true] .bk-card-inner{transform:rotateY(-180deg)}.bk-card-face{position:absolute;inset:0;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:.6rem;padding:2.25rem 1.5rem;border:1px solid var(--border-soft);border-radius:var(--radius-card);background:var(--bk-paper,var(--surface-raised));box-shadow:var(--shadow-card);-webkit-backface-visibility:hidden;backface-visibility:hidden}.bk-card-back{transform:rotateY(180deg)}[dir=rtl] .bk-card-back{transform:rotateY(-180deg)}.bk-card-side{top:.75rem;inset-inline-start:1rem;font-weight:800;letter-spacing:.04em}.bk-card-chip,.bk-card-side{position:absolute;font-size:.75rem;color:var(--text-muted)}.bk-card-chip{bottom:.75rem;inset-inline-end:1rem;padding:.1rem .6rem;border:1px solid var(--border-soft);border-radius:999px;font-weight:700}.bk-card-term{font-family:var(--font-display);font-size:clamp(1.75rem,5vw,2.75rem);font-weight:900;line-height:1.2;overflow-wrap:anywhere}.bk-card-meaning{font-size:clamp(1.25rem,3.5vw,1.75rem);font-weight:800;line-height:1.35;overflow-wrap:anywhere}.bk-card-example{max-width:28rem;font-size:.9375rem;line-height:1.6;color:var(--text-muted)}.bk-card-listen{position:absolute;top:.4rem;inset-inline-end:.4rem;z-index:1}.bk-card-listen .book-listen,.bk-words-listen .book-listen{background:var(--action-face);color:var(--action-ink)}.bk-card-listen .book-listen[aria-pressed=true],.bk-words-listen .book-listen[aria-pressed=true]{background:var(--text-strong)}.bk-card-listen .book-listen[data-small]{box-sizing:content-box;padding:.625rem;background-clip:content-box;box-shadow:none}.bk-card-count{font-size:.875rem;font-weight:700;color:var(--text-muted)}.bk-card-actions{display:flex;flex-wrap:wrap;justify-content:center;gap:.5rem;width:min(100%,32rem)}.bk-card-actions>*{flex:1 1 8rem}.bk-card-more{display:flex;flex-wrap:wrap;justify-content:center;gap:.25rem}.bk-cards-empty{padding:1.5rem 1rem;border:1px dashed var(--field-border);border-radius:var(--radius-card);text-align:center;font-size:.9375rem;font-weight:600;color:var(--text-muted)}.bk-cards-done{display:flex;flex-direction:column;align-items:center;gap:.6rem;color:var(--text-strong)}.bk-words{padding-top:.75rem;border-top:1px solid var(--border-soft)}.bk-words-summary{display:flex;align-items:center;gap:.6rem;min-height:2.75rem;cursor:pointer;font-weight:800;list-style:none}.bk-words-summary::-webkit-details-marker{display:none}.bk-words-summary:before{content:"";width:.5rem;height:.5rem;margin-inline-start:.25rem;border-inline-end:2px solid currentColor;border-bottom:2px solid;transform:rotate(-45deg);transition:transform var(--mo-2) var(--ez-out)}.bk-words[open]>.bk-words-summary:before,[dir=rtl] .bk-words-summary:before{transform:rotate(45deg)}[dir=rtl] .bk-words[open]>.bk-words-summary:before{transform:rotate(-45deg)}.bk-words-listen{display:flex;align-items:center;gap:.6rem;margin:.25rem 0 .5rem}.bk-words-listen:not(:has(.book-listen)){display:none}.bk-words-list{display:flex;flex-direction:column}.bk-words-row{display:flex;align-items:center;gap:.75rem;min-height:2.75rem;padding:.4rem .5rem;border-bottom:1px solid var(--border-soft);font-size:.9375rem}.bk-words-row:last-child{border-bottom:0}.bk-words-term{flex:1 1 40%;min-width:0;font-weight:800;color:var(--text-strong)}.bk-words-meaning{flex:1 1 60%;min-width:0;color:var(--text-muted)}.bk-words-row[data-known] .bk-words-term{color:var(--success)}.bk-cover-go{display:block;margin-top:1.25rem}@media (prefers-reduced-motion:reduce){.bk-card-inner,.bk-words-summary:before{transition:none}}