/* Classroom-first question bank: full desktop width and a familiar right-hand tool rail. */
#practice-app .pb-library-preview{display:block;width:100%;padding:12px;margin-top:14px;background:white;text-align:left}.pb-library-preview img{display:block;width:100%;max-height:155px;object-fit:cover;object-position:top}.pb-library-preview span{display:block;font-size:15px;color:#2461c7;margin-top:8px}
#practice-app .pb-one-screen .pb-original-image{height:calc(100% - 32px)}.pb-one-screen .pb-original-image img{width:100%;height:100%;object-fit:contain}#practice-app.pb-large-type .pb-one-screen .pb-original-image{height:auto}.pb-large-type .pb-one-screen .pb-original-image img{height:auto}
#paper-list{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;margin-bottom:24px}#practice-app #paper-list .pb-paper{display:flex;flex-direction:column;align-items:stretch;margin:0;padding:18px 20px;gap:16px}#paper-list .pb-paper h2{font-size:23px!important;line-height:1.4}#paper-list .pb-paper-actions{margin-top:auto;max-width:none}#paper-list .pb-paper p{font-size:15px}#practice-app .pb-filters{flex-wrap:wrap}.pb-filters label:has(#section-filter){flex:1}.pb-filters #section-filter{max-width:none;min-width:160px}.pb-filters .pb-search{min-width:180px}
#practice-app .pb-book-stage{min-height:0;height:calc(100vh - 180px);display:flex;flex-direction:column;padding:18px 24px}.pb-book-work{display:grid;grid-template-columns:minmax(0,1.75fr) minmax(300px,1fr);gap:22px;min-height:0;flex:1}.pb-book-reading,.pb-book-answer{min-height:0;overflow:auto;overscroll-behavior:contain;padding-right:8px}.pb-book-reading{border:1px solid var(--pb-line);border-radius:10px;background:white}.pb-book-reading-note{position:sticky;top:0;padding:7px 12px;background:#eaf2ff;color:#345475;font-size:15px;z-index:1}.pb-original-image{display:block!important;width:100%;padding:10px!important;border:0!important;background:white!important;border-radius:0!important;text-align:left}.pb-original-image img{width:100%;height:auto;display:block;background:white}.pb-book-reading .pb-original-image+.pb-original-image{border-top:2px dashed #bfd4e6!important}.pb-book-answer .pb-options{grid-template-columns:1fr 1fr;gap:12px}.pb-book-answer .pb-options label{font-size:30px;min-height:64px}.pb-book-answer textarea{width:100%;resize:vertical;max-height:260px;min-height:140px;padding:12px;border:1px solid var(--pb-line);border-radius:10px;background:var(--pb-bg);color:var(--pb-ink);font-family:inherit;font-size:22px;line-height:1.5}.pb-book-answer .pb-help.closed{display:none}.pb-book-answer .pb-help{padding:15px;min-height:0;font-size:24px}.pb-book-answer .pb-help:has(.pb-original-image){padding:10px;border:0;background:var(--pb-soft)}.pb-book-answer .pb-feedback{font-size:18px;line-height:1.5;color:var(--pb-accent);margin:10px 0}.pb-book-answer .pb-feedback:empty{display:none}.pb-book-answer #answer-form[hidden]{display:none}.pb-book-stage .pb-actions{margin-top:12px}.pb-book-stage .pb-source{font-size:13px!important;margin-top:8px!important}.pb-book-stage h2{font-size:28px!important;margin-bottom:12px!important}.pb-teach .pb-book-work{grid-template-columns:minmax(0,1.75fr) minmax(300px,1fr)}.pb-large-type .pb-book-reading .pb-original-image{width:120%;max-width:none}.pb-book-reading:has(.pb-original-image:focus-visible){outline-offset:-4px}
#practice-app .pb-short-options .pb-help{padding:14px 18px}#practice-app .pb-short-options .pb-help .pb-trap{margin-top:8px;padding:8px 12px}
#practice-app .pb-stage.pb-short-options:has(.pb-figure) .pb-help:not(.closed),#practice-app .pb-short-options .pb-teach-options{width:48%}
#practice-app .pb-short-options .pb-figure{width:48%}#practice-app .pb-short-options #answer-form{width:48%}.pb-short-options .pb-options{grid-template-columns:1fr 1fr}#practice-app .pb-inline-feedback{display:inline;font-size:17px;margin-right:16px}.pb-short-options .pb-inline-feedback{display:block!important}
.pb-stage:has(.pb-figure):has(.pb-help:not(.closed)) #answer-form,.pb-stage:has(.pb-figure):has(.pb-help:not(.closed)) .pb-teach-options{display:none!important}#practice-app .pb-stage:has(.pb-figure) .pb-help:not(.closed){width:64%;margin:0;clear:none}.pb-inline-feedback{font-size:19px;color:var(--pb-accent);margin:8px 0}
.pb-paper{display:flex;justify-content:space-between;align-items:center;gap:24px;padding:22px 26px;margin:0 0 25px;border:1px solid #b5d5eb;border-left:6px solid #0aa89b;border-radius:16px;background:linear-gradient(110deg,var(--pb-bg),var(--pb-soft))}.pb-paper-tag{display:inline-block;font-size:16px;font-weight:700;color:#088f88;margin-bottom:9px}.pb-paper h2{font-size:26px!important;margin:0 0 8px!important}.pb-paper p{font-size:17px;margin:0;color:var(--pb-muted)}.pb-paper-actions{display:flex;flex-wrap:wrap;gap:10px;flex-shrink:0;max-width:390px}.pb-paper-actions button{font-size:18px!important}
#practice-app .pb-figure{float:right;width:32%;margin:0 0 18px 24px;padding:12px;background:white;border-color:#bcd3e8}.pb-figure img{display:block;max-width:100%;width:auto;max-height:175px;margin:auto;object-fit:contain}.pb-figure span{display:block;color:#2664c9;font-size:15px;margin-top:8px}.pb-stage:has(.pb-figure) .pb-work{grid-template-columns:minmax(0,1.2fr) minmax(0,1fr)}.pb-stage:has(.pb-figure) .pb-work .pb-help{grid-column:2}.pb-stage:has(.pb-figure) .pb-work{display:block}.pb-stage:has(.pb-figure) #answer-form{width:64%}.pb-stage:has(.pb-figure) .pb-help{float:right;width:32%;clear:right;margin-top:0}.pb-stage:has(.pb-figure) .pb-work:after{content:'';display:block;clear:both}.pb-stage:has(.pb-figure) .pb-help.closed{display:none}.pb-teach .pb-stage:has(.pb-figure) .pb-teach-options{width:64%}.pb-teach .pb-stage:has(.pb-figure) .pb-help:not(.closed){float:none;width:100%;margin-top:18px}.pb-stage:has(.pb-figure) .pb-help:not(.closed){float:none;width:100%;margin-top:18px;min-height:0}.pb-stage:has(.pb-figure) .pb-help:not(.closed) .pb-step-text{margin-bottom:0}
#pb-ink{position:fixed;inset:0;pointer-events:none;touch-action:none;z-index:900}#pb-ink.active{pointer-events:auto;cursor:crosshair}#pb-ink[hidden]{display:none}#practice-app #pb-tools .physics-draw-colors{display:grid;grid-template-columns:1fr 1fr;gap:5px;padding:5px 0}#practice-app #pb-tools .physics-draw-colors[hidden]{display:none}#practice-app #pb-tools [data-ink]{width:23px;height:23px;min-height:23px;border-radius:50%;background:var(--ink);padding:0;border:3px solid transparent}#practice-app #pb-tools [data-ink][aria-pressed=true]{border-color:var(--pb-bg);outline:2px solid var(--pb-ink)}#practice-app #pb-tools #tool-pen[aria-pressed=true]{background:#ffe5e4;color:#c32d30}
#image-viewer{width:calc(100vw - 64px);max-width:none;height:calc(100vh - 64px);max-height:none;padding:0;border:1px solid var(--pb-line);border-radius:16px;background:var(--pb-bg);color:var(--pb-ink);overflow:hidden}#image-viewer::backdrop{background:#091a31bf}.pb-imagebar{display:flex;align-items:center;gap:12px;padding:14px 18px;border-bottom:1px solid var(--pb-line);height:76px}.pb-imagebar strong{margin-right:auto;font-size:22px}.pb-imagebar button{font-size:18px!important;padding:8px 14px!important}#image-scroll{overflow:auto;height:calc(100% - 76px);padding:20px;background:#dde5ed}#image-full{display:block;max-width:none;height:auto;margin:0 auto;background:white}
.pb-help .pb-feedback.is-revise{background:#fff0de!important;color:#915319!important}html[data-science-theme=dark] .pb-help .pb-feedback.is-revise{background:#493b22!important;color:#ffd794!important}
body:has(#practice-app){background:#f1f5fc;font-family:"Microsoft YaHei","Noto Sans SC",system-ui,sans-serif}
body:has(#practice-app) .site-header.site-shell{width:calc(100% - 48px);max-width:none}
#practice-app{width:calc(100% - 48px);max-width:none;margin:0 24px 32px;--pb-accent:#225fdd;--pb-bg:#fff;--pb-ink:#193451;--pb-muted:#536c86;--pb-soft:#edf3ff;--pb-line:#d5e1ef;--pb-extra:0px;color:var(--pb-ink);font-size:20px}
#practice-app.pb-large-type{--pb-extra:3px}
#practice-app :is(button,input,select){font:inherit}#practice-app button{border:1px solid var(--pb-line);border-radius:10px;padding:10px 17px;background:var(--pb-bg);color:var(--pb-ink);cursor:pointer;transition:background .15s,border-color .15s}
#practice-app button:hover{border-color:var(--pb-accent);background:var(--pb-soft)}#practice-app button:disabled{opacity:.4;cursor:default}#practice-app button.pb-primary{background:var(--pb-accent);border-color:var(--pb-accent);color:white;font-weight:700;box-shadow:0 3px 9px #225fdd17}#practice-app button.pb-primary:hover{background:#174cbd}
#practice-app :is(button,input,select,a,summary):focus-visible{outline:3px solid #f5b739;outline-offset:3px}#practice-app :is(input,select){border:1px solid #bdcfe4;border-radius:9px;background:var(--pb-bg);color:inherit;padding:10px 12px;min-width:0}#practice-app input[type=checkbox],#practice-app input[type=radio]{accent-color:var(--pb-accent)}
#practice-app h1{font-size:44px;margin:4px 0 10px;letter-spacing:.025em}#practice-app h2{font-size:28px;margin:0 0 12px}#practice-app h3{font-size:22px}
.pb-heading{display:flex;justify-content:space-between;align-items:center;gap:30px;padding:24px 0 22px}.pb-heading p{margin:4px 0;color:var(--pb-muted);font-size:21px}.pb-heading .pb-eyebrow{font-size:17px;color:#2862c7;font-weight:700}.pb-heading>button{font-size:21px!important;padding:14px 22px!important}#basket-count{display:inline-grid;place-items:center;min-width:28px;height:28px;border-radius:50%;background:#ffffff2e;margin-left:8px}
.pb-chapters{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:18px;margin-bottom:25px}#practice-app .pb-chapter{--chapter:#2869eb;--wash:#ecf3ff;text-align:left;background:var(--pb-bg);border:1px solid var(--pb-line);border-top:5px solid var(--chapter);padding:20px 24px;position:relative;border-radius:14px;box-shadow:0 3px 14px #1e437406}#practice-app .pb-chapter:nth-child(2){--chapter:#009f9b;--wash:#e6f8f5}#practice-app .pb-chapter:nth-child(3){--chapter:#8054df;--wash:#f2edff}#practice-app .pb-chapter:nth-child(4){--chapter:#e68120;--wash:#fff3df}
.pb-chapter strong{display:block;font-size:clamp(25px,1.6vw,32px);margin:10px 0;color:var(--chapter)}.pb-chapter small{font-size:17px;color:var(--pb-muted)}#practice-app .pb-chapter.active{background:var(--wash);border-color:var(--chapter);box-shadow:0 0 0 1px var(--chapter)}#practice-app .pb-chapter:hover{background:var(--wash)}
.pb-layout{display:grid;grid-template-columns:minmax(0,1fr) clamp(330px,23vw,440px);gap:26px;align-items:start}.pb-library{min-width:0}.pb-filters{display:flex;gap:16px;align-items:end;padding:18px;background:var(--pb-bg);border:1px solid var(--pb-line);border-radius:14px}.pb-filters label,.pb-setlabel{display:grid;gap:8px;font-size:17px;font-weight:700}.pb-filters select{width:100%;font-size:19px!important;max-width:310px}.pb-search{flex:1;min-width:130px}.pb-search input{width:100%;font-size:19px!important}.pb-listbar{display:flex;justify-content:space-between;align-items:center;gap:12px;margin:20px 0 8px}.pb-listbar>div{display:flex;gap:10px}.pb-listbar>span{font-size:20px;font-weight:700}.pb-small{font-size:16px;line-height:1.6;color:var(--pb-muted)}#practice-scope{margin:10px 0 17px}
.pb-question{border:1px solid var(--pb-line);border-radius:15px;background:var(--pb-bg);padding:21px 24px;margin-bottom:16px;box-shadow:0 3px 12px #29467305}.pb-question-top{display:flex;justify-content:space-between;align-items:center;gap:20px}.pb-question h3{font-size:27px!important;margin:11px 0 6px}.pb-question p{margin:10px 0;font-size:23px;line-height:1.6}.pb-question .pb-goal{color:#127b86;font-size:18px;font-weight:600}.pb-tag{display:inline-block;font-size:15px;padding:4px 8px;border-radius:6px;background:#edf2f9;color:#516b86;margin:0 6px 3px 0}.pb-tag.progress{background:#e4f5ec;color:#237351}.pb-rowactions{display:flex;gap:10px;flex-shrink:0}.pb-rowactions button{font-size:18px!important}.pb-source{font-size:14px;line-height:1.5;color:var(--pb-muted);margin-top:10px}.pb-question details{font-size:18px;margin-top:12px;color:var(--pb-muted)}.pb-question details p{font-size:19px}.pb-question summary{cursor:pointer;width:max-content}
.pb-basket{position:sticky;top:16px;padding:24px;border-radius:16px;background:var(--pb-bg);border:1px solid var(--pb-line);border-top:5px solid #f1a527;box-shadow:0 7px 25px #29467308;max-height:calc(100vh - 32px);overflow-y:auto}.pb-basket>h2{font-size:28px!important}.pb-basket-item{padding:13px 0;border-bottom:1px solid var(--pb-line);font-size:19px;line-height:1.5}.pb-basket-controls{display:flex;gap:6px;align-items:center;margin-top:9px}.pb-basket-controls label{font-size:16px;margin-right:auto;white-space:nowrap}#practice-app .pb-basket-controls button{padding:5px 9px;font-size:16px}.pb-setlabel{margin-top:18px}.pb-setlabel input{width:100%;font-size:18px!important}.pb-stack{display:flex;flex-wrap:wrap;gap:10px;margin-top:14px}.pb-stack button{font-size:18px!important}#start-teach{flex:1;min-width:100%;background:#07999c!important;border-color:#07999c!important}.pb-saved{display:flex;gap:7px;margin:10px 0}.pb-saved button:first-child{flex:1;text-align:left;overflow-wrap:anywhere;font-size:18px!important}.pb-saved small{display:block;font-size:14px;color:var(--pb-muted);margin-top:5px}.pb-saved button:last-child{font-size:15px!important;padding:7px!important}.pb-empty{padding:24px 0;color:var(--pb-muted);line-height:1.6;font-size:19px}
body.pb-in-session>.site-header,body.pb-in-session>.science-mobile-navigation,body.pb-in-session>footer{display:none!important}body.pb-in-session #practice-app{width:calc(100% - 112px);max-width:none;margin:0 88px 0 24px}.pb-sessionhead{height:56px;display:flex;align-items:center;justify-content:space-between;gap:22px}.pb-sessionhead strong{font-size:22px;overflow:hidden;white-space:nowrap;text-overflow:ellipsis;max-width:55%}.pb-sessionhead>button{font-size:17px!important;padding:8px 15px!important}.pb-session-note{font-size:18px;color:#617897}#session-index{display:flex;gap:8px;overflow-x:auto;max-width:100%;padding:0 0 10px}#session-index button{flex-shrink:0;padding:5px 13px;font-size:18px;min-width:40px}#session-index button.active{background:var(--pb-accent);border-color:var(--pb-accent);color:white;font-weight:700}
.pb-stage{background:var(--pb-bg);border:1px solid var(--pb-line);border-top:4px solid #2c70e8;border-radius:16px;padding:24px 30px;min-height:calc(100vh - 185px)}.pb-stage h2{font-size:calc(clamp(30px,1.8vw,37px) + var(--pb-extra))!important;margin:0 0 15px!important;line-height:1.3}.pb-prompt{font-size:calc(clamp(31px,1.9vw,38px) + var(--pb-extra));line-height:1.52;white-space:pre-line;margin:0 0 23px}.pb-work{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:30px;align-items:start}.pb-work.no-diagram{grid-template-columns:minmax(0,1.05fr) minmax(0,1fr)}.pb-work.with-diagram-study{grid-template-columns:minmax(0,.78fr) minmax(0,.95fr) minmax(0,1.1fr);gap:22px}.pb-work svg{width:100%;max-height:350px;display:block}.pb-part{margin-bottom:14px}.pb-part-label{font-size:calc(24px + var(--pb-extra));font-weight:700;margin-bottom:9px;line-height:1.4}.pb-part:has(.pb-numeric){display:grid;grid-template-columns:minmax(115px,1fr) minmax(165px,1.6fr);gap:12px;align-items:center}.pb-part:has(.pb-numeric) .pb-part-label{margin:0}.pb-numeric{display:flex;gap:12px;align-items:center;font-size:calc(25px + var(--pb-extra))}.pb-numeric input{width:200px;max-width:70%;font-size:calc(30px + var(--pb-extra))!important;padding:10px 12px!important;font-variant-numeric:tabular-nums}.pb-options{display:grid;gap:10px}.pb-options label{display:flex;gap:12px;align-items:center;font-size:calc(clamp(24px,1.5vw,30px) + var(--pb-extra));line-height:1.4;padding:10px 14px;border:1px solid var(--pb-line);border-radius:10px;cursor:pointer}.pb-options label:has(input:checked){border-color:#2a6de0;background:#ebf2ff;box-shadow:inset 3px 0 #2a6de0}.pb-options input{width:20px;height:20px;flex-shrink:0}.pb-help{background:var(--pb-soft);padding:23px 25px;border-radius:13px;border-left:4px solid #447ce9;min-height:200px;font-size:calc(clamp(25px,1.55vw,31px) + var(--pb-extra));line-height:1.55;overflow-wrap:anywhere}.pb-help p{margin:10px 0}.pb-explanation-label{font-size:18px;letter-spacing:.04em;font-weight:800;color:#2664c9;margin-bottom:15px}.pb-help .pb-small{font-size:19px}.pb-help .pb-feedback{font-size:20px;margin:0 0 16px;padding:9px 12px;background:#dff3e9;color:#226c4e;border-radius:8px;line-height:1.45}.pb-help .pb-feedback:empty{display:none}.pb-answer-text{color:#146379;font-weight:650}.pb-help .pb-trap{font-size:21px;margin:18px 0 0;padding:13px 15px;background:#fff1d5;color:#835110;border-radius:9px}.pb-trap b{display:block;font-size:17px;margin-bottom:4px}
#answer-form>button{font-size:21px;padding:11px 23px;margin-top:3px}.pb-actions{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-top:21px}.pb-actions button{font-size:19px!important;padding:10px 15px!important}#show-hint{background:#fff5df!important;border-color:#f4cc76!important;color:#875916!important}#show-step{background:#e7f7f4!important;border-color:#95d9cc!important;color:#077c72!important}.pb-model{font-size:18px;color:#185bc3;text-decoration:underline;margin-left:8px}.pb-stage .pb-source{margin-top:15px;font-size:14px}.pb-sessionfoot{width:100%!important;display:flex;justify-content:space-between;align-items:center;gap:15px;margin:0!important;padding:10px 0!important;border:0!important;font-size:19px!important;color:var(--pb-muted)!important}.pb-sessionfoot button{font-size:20px!important;padding:9px 21px!important}
.pb-teach #answer-form{display:none}.pb-teach .pb-work.no-diagram{grid-template-columns:1fr}.pb-teach .pb-help{max-width:1450px;width:100%;margin:auto;font-size:calc(clamp(29px,1.85vw,37px) + var(--pb-extra));min-height:230px}.pb-teach .pb-help.closed{display:grid;align-content:center}.pb-teach .pb-work.has-choice{grid-template-columns:1.1fr 1fr}.pb-teach .pb-work.has-choice:has(svg){grid-template-columns:.8fr .9fr 1.1fr}.pb-teach-options{font-size:calc(clamp(27px,1.65vw,33px) + var(--pb-extra));line-height:1.5}.pb-teach-options p{margin:9px 0}.pb-teach-options>b{font-size:20px;color:var(--pb-muted)}.pb-optional{font-size:17px;color:#b17614}.pb-result{max-width:1100px;margin:30px auto;font-size:27px;line-height:1.6}.pb-result strong{color:var(--pb-accent)}.pb-result button{margin:8px}.pb-result .pb-small{font-size:19px}.pb-toast{position:fixed;bottom:15px;left:50%;transform:translateX(-50%);padding:12px 23px;border-radius:10px;background:#214b80;color:white;z-index:10000;max-width:75%;font-size:18px;box-shadow:0 6px 30px #19385425}#pb-message:empty{display:none}.pb-hidden{display:none!important}
#practice-app #pb-tools{position:fixed;right:10px;top:50%;transform:translateY(-50%);z-index:1000;display:flex;flex-direction:column;width:64px;gap:4px;padding:5px;border:1px solid #ccdbea;border-radius:15px;background:var(--pb-bg);box-shadow:0 6px 25px #18395716;max-height:calc(100vh - 20px);overflow:auto}#practice-app #pb-tools[hidden]{display:none}#practice-app #pb-tools button{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;min-height:61px;padding:8px 4px;border:0;border-radius:9px;font-size:14px;font-weight:600;background:transparent}#pb-tools svg{width:23px;height:23px;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}#practice-app #pb-tools button:hover,#practice-app #pb-tools button[aria-pressed=true]{background:#e9f1ff;color:#2865d8}#practice-app #pb-tools [data-science-whiteboard]{color:#0b8a83;background:#e8f7f4}#pb-tools small{font-size:11px;color:var(--pb-muted)}#practice-app #pb-tools #tool-collapse{min-height:45px;border-top:1px solid var(--pb-line);border-radius:0;margin-top:4px}#pb-tools.is-collapsed>button:not(#tool-collapse){display:none!important}#pb-tools.is-collapsed #tool-collapse svg{transform:rotate(180deg)}html:has(body.pb-in-session) #science-theme-toggle{display:none!important}
@media(max-width:1450px){#practice-app{width:calc(100% - 36px);margin-left:18px;margin-right:18px;font-size:18px}.pb-layout{grid-template-columns:minmax(0,1fr) 330px;gap:20px}.pb-chapters{gap:14px}.pb-heading{padding:18px 0}.pb-heading p{font-size:19px}.pb-heading .pb-eyebrow{font-size:16px}.pb-chapter strong{font-size:25px}#practice-app .pb-chapter{padding:15px 18px}.pb-chapter small{font-size:16px}.pb-filters{gap:12px;padding:14px}.pb-filters label{font-size:16px}.pb-filters :is(input,select){font-size:17px!important}.pb-question{padding:18px 20px}.pb-question p{font-size:22px}.pb-question h3{font-size:25px!important}.pb-rowactions{gap:7px}.pb-rowactions button{padding:9px 12px!important}.pb-basket{padding:20px}.pb-work.with-diagram-study{grid-template-columns:.8fr .9fr 1.1fr;gap:20px}.pb-part:has(.pb-numeric){grid-template-columns:1fr;gap:5px}.pb-work.no-diagram .pb-part:has(.pb-numeric){grid-template-columns:minmax(115px,1fr) minmax(165px,1.6fr)}}
@media(max-height:800px){.pb-sessionhead{height:48px}.pb-sessionhead strong{font-size:20px}#session-index{padding-bottom:8px}.pb-stage{min-height:calc(100vh - 165px);padding:17px 24px}.pb-stage h2{margin-bottom:12px!important}.pb-prompt{font-size:calc(31px + var(--pb-extra));line-height:1.45;margin-bottom:17px}.pb-part{margin-bottom:10px}.pb-part-label{font-size:calc(22px + var(--pb-extra));margin-bottom:7px}.pb-numeric{font-size:calc(23px + var(--pb-extra))}.pb-numeric input{font-size:calc(27px + var(--pb-extra))!important;padding:8px 10px!important}.pb-options{gap:8px}.pb-options label{font-size:calc(24px + var(--pb-extra));padding:7px 12px}.pb-help{font-size:calc(25px + var(--pb-extra));padding:17px 20px;min-height:180px}.pb-help .pb-small{font-size:18px}.pb-explanation-label{font-size:17px;margin-bottom:10px}.pb-help .pb-trap{font-size:20px;margin-top:12px;padding:10px 12px}.pb-teach .pb-help{font-size:calc(28px + var(--pb-extra));min-height:195px}.pb-teach-options{font-size:calc(27px + var(--pb-extra))}.pb-actions{gap:8px;margin-top:15px}.pb-actions button{padding:8px 12px!important;font-size:18px!important}.pb-stage .pb-source{margin-top:10px;font-size:13px}.pb-sessionfoot{padding:8px 0!important}.pb-work svg{max-height:275px}#answer-form>button{padding:9px 20px;font-size:20px}.pb-help .pb-feedback{font-size:18px;margin-bottom:10px}.pb-model{font-size:16px}}
html[data-science-theme=dark] body:has(#practice-app){background:#101b2c}html[data-science-theme=dark] #practice-app{--pb-bg:#19293e;--pb-ink:#e8f0ff;--pb-muted:#a8bbd4;--pb-soft:#203653;--pb-line:#344a64;--pb-accent:#417beb}html[data-science-theme=dark] .pb-heading .pb-eyebrow{color:#81afff}html[data-science-theme=dark] #practice-app .pb-chapter{--chapter:#74a5ff;--wash:#233958}html[data-science-theme=dark] #practice-app .pb-chapter:nth-child(2){--chapter:#4bd1c4;--wash:#173f43}html[data-science-theme=dark] #practice-app .pb-chapter:nth-child(3){--chapter:#bb9aff;--wash:#352b52}html[data-science-theme=dark] #practice-app .pb-chapter:nth-child(4){--chapter:#ffc06c;--wash:#453928}html[data-science-theme=dark] .pb-tag{background:#2a3e57;color:#bfd1ea}html[data-science-theme=dark] .pb-tag.progress{background:#244b43;color:#8fe0bd}html[data-science-theme=dark] .pb-question .pb-goal{color:#65cfc9}html[data-science-theme=dark] .pb-explanation-label{color:#90b8ff}html[data-science-theme=dark] .pb-answer-text{color:#83dedb}html[data-science-theme=dark] .pb-help .pb-trap{background:#493b22;color:#ffd794}html[data-science-theme=dark] .pb-help .pb-feedback{background:#23483e;color:#9ee1bf}html[data-science-theme=dark] .pb-options label:has(input:checked){background:#25466b}html[data-science-theme=dark] #practice-app #pb-tools [data-science-whiteboard]{background:#224640;color:#7addcb}html[data-science-theme=dark] #practice-app #pb-tools button:hover{background:#294364;color:#a6c8ff}
/* Native book text and source figures are independent, selectable classroom content. */
.pb-question .pb-library-stem{display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden;white-space:pre-line}
#practice-app .pb-book-reading{background:var(--pb-bg);padding:16px 20px;border-top:4px solid #159f9b}
.pb-native-stem{white-space:pre-line;font-size:calc(clamp(27px,1.65vw,33px) + var(--pb-extra));line-height:1.65;margin:0 0 18px;overflow-wrap:anywhere}
.pb-book-answer .pb-options{grid-template-columns:1fr}.pb-book-answer .pb-options label{font-size:calc(clamp(25px,1.5vw,30px) + var(--pb-extra));line-height:1.55;min-height:58px;align-items:flex-start}.pb-book-answer .pb-options input{margin-top:10px}
#practice-app .pb-book-answer .pb-help{font-size:calc(clamp(26px,1.6vw,32px) + var(--pb-extra));line-height:1.65}.pb-step-text{white-space:pre-line}
.pb-native-figures{display:flex;flex-wrap:wrap;align-items:flex-start;justify-content:center;gap:16px}
#practice-app .pb-source-figure{max-width:100%;background:white;border-color:#d4dce7;padding:10px 14px;margin:0 0 16px;text-align:center}
.pb-source-figure img{display:block;width:auto;height:auto;max-width:100%;max-height:330px;margin:auto;object-fit:contain}.pb-source-figure span{display:block;font-size:15px;color:#305f98;margin-top:8px}
.pb-table-scroll{overflow-x:auto;margin:12px 0 22px}.pb-data-table{border-collapse:collapse;width:100%;font-size:calc(22px + var(--pb-extra));font-variant-numeric:tabular-nums}.pb-data-table th,.pb-data-table td{border:1px solid var(--pb-line);padding:10px;text-align:center;white-space:nowrap}.pb-data-table th{background:var(--pb-soft)}
.pb-source-row{display:flex;align-items:center;gap:16px;margin-top:8px;flex-wrap:wrap}.pb-source-links{display:flex;gap:10px;flex-wrap:wrap;margin-left:auto}#practice-app .pb-source-links button{font-size:14px;padding:5px 9px;color:var(--pb-muted)}.pb-source-row .pb-source{margin:0!important}
.pb-teach .pb-book-work{grid-template-columns:minmax(0,1.5fr) minmax(340px,1fr)}.pb-book-reading .pb-teach-options{border-top:1px solid var(--pb-line);padding-top:10px;margin-top:10px}
@media(min-width:1700px){.pb-source-figure img{max-height:420px}}
#practice-app .pb-source-figure{min-width:min(100%,300px)}.pb-source-figure img{min-width:min(100%,260px)}
#practice-app .pb-favorite{white-space:nowrap}#practice-app .pb-favorite[aria-pressed=true]{background:#fff2d0;border-color:#efbd4e;color:#80530c}.pb-rowactions{flex-wrap:wrap;justify-content:flex-end}#session-favorite .pb-favorite{font-size:18px;padding:7px 14px}.pb-listbar{flex-wrap:wrap;gap:12px}html[data-science-theme=dark] #practice-app .pb-favorite[aria-pressed=true]{background:#4a391c;border-color:#aa8232;color:#ffdc8e}
.pb-reading-hint{font-size:15px;color:var(--pb-muted);margin-bottom:10px}
/* Library workspace: compact navigation, document rows and an optional teaching list. */
body:not(.pb-in-session):has(#practice-app){background:#f4f6f8}
#library-view{--pb-accent:#087e83;--pb-ink:#183247;--pb-muted:#617283;--pb-bg:#fff;--pb-line:#dce4e9;--pb-soft:#edf6f6}
#library-view [hidden]{display:none!important}
#library-view .pb-heading{padding:18px 0 16px;align-items:center;gap:20px}
#library-view .pb-heading h1{font-size:34px;margin:3px 0 0;letter-spacing:0}
#library-view .pb-heading .pb-eyebrow{font-size:15px;color:var(--pb-muted);font-weight:500;margin:0}
.pb-heading-actions{display:flex;align-items:center;gap:22px}.pb-heading-actions>span{font-size:16px;color:var(--pb-muted)}
#library-view #open-sets{background:var(--pb-bg);border-color:var(--pb-line);font-size:18px;padding:10px 16px;border-radius:7px;box-shadow:none}
#library-view #basket-count{background:#e4f2f1;color:#086d73;font-size:16px;margin-left:9px}
.pb-library-tabs{display:flex;gap:28px;border-bottom:1px solid var(--pb-line);margin-bottom:20px}
#library-view .pb-library-tabs button{font-size:21px;font-weight:600;padding:12px 2px 14px;border:0;border-bottom:3px solid transparent;border-radius:0;background:transparent;color:var(--pb-muted)}
#library-view .pb-library-tabs button[aria-pressed=true]{color:var(--pb-accent);border-bottom-color:var(--pb-accent);background:transparent}
#library-view .pb-layout{display:grid;grid-template-columns:minmax(0,1fr);gap:24px;align-items:start}
#library-view .pb-layout.with-basket{grid-template-columns:minmax(0,1fr) 350px}
.pb-library-main{min-width:0}
#library-view .pb-chapters{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:16px}
#library-view .pb-chapter{display:flex;align-items:center;gap:9px;border:1px solid transparent;border-radius:6px;padding:10px 14px;background:transparent;box-shadow:none;color:var(--pb-muted)}
#library-view .pb-chapter strong{font-size:19px;color:inherit;margin:0;font-weight:500}
#library-view .pb-chapter span{font-size:14px}
#library-view .pb-chapter.active{background:#e2f0ef;border-color:#b5d8d5;color:#076b70}
#library-view .pb-filters,#library-view .pb-paper-filters{display:flex;align-items:end;gap:16px;background:var(--pb-bg);padding:16px 18px;border:1px solid var(--pb-line);border-radius:8px}
#library-view .pb-filters label,#library-view .pb-paper-filters label{display:grid;gap:7px;font-size:14px;font-weight:500;color:var(--pb-muted)}
#library-view .pb-filters label:has(#section-filter){flex:1.1}
#library-view .pb-filters .pb-search{flex:1.3}
#library-view :is(input[type=search],select){font-size:17px!important;padding:9px 12px;border-radius:6px;background:var(--pb-bg);border-color:var(--pb-line);color:var(--pb-ink);height:42px}
#library-view .pb-listbar{margin:18px 0 7px;gap:14px}
#library-view .pb-listbar>span{font-size:17px;font-weight:500;color:var(--pb-muted)}
#library-view button{border-radius:6px;box-shadow:none}
#library-view button.pb-primary{background:var(--pb-accent);border-color:var(--pb-accent);color:white;box-shadow:none}
#library-view button.pb-primary:hover{background:#086d72}
#library-view .pb-listbar button{font-size:17px;padding:9px 15px}
#library-view #practice-scope{font-size:14px;margin:6px 0 14px}
#library-view .pb-question{border:1px solid var(--pb-line);border-radius:8px;box-shadow:none;background:var(--pb-bg);padding:18px 22px;margin-bottom:12px}
#library-view .pb-question-top{align-items:flex-start;gap:22px}
#library-view .pb-question h3{font-size:22px!important;line-height:1.45;margin:8px 0 0}
#library-view .pb-question .pb-library-stem{font-size:22px;line-height:1.6;margin:12px 0 9px;-webkit-line-clamp:2}
#library-view .pb-tag{font-size:13px;background:#eef2f5;color:#586f80;border-radius:4px;padding:3px 7px;margin-right:7px}
#library-view .pb-tag.progress{color:#297565;background:#eaf4ef}
#library-view .pb-question .pb-goal{font-size:15px;margin:6px 0;color:#08777c}
#library-view .pb-source,#library-view .pb-question details{font-size:14px;color:var(--pb-muted)}
#library-view .pb-question details{margin-top:8px}#library-view .pb-question details p{font-size:18px;line-height:1.6}
#library-view .pb-rowactions{gap:8px;flex-shrink:0}#library-view .pb-rowactions button{font-size:16px;padding:8px 12px;border-radius:6px}
#library-view .pb-favorite[aria-pressed=true]{background:#fff4d9;border-color:#e7cd8c;color:#865d12}
#library-view .pb-basket{position:sticky;top:16px;max-height:calc(100vh - 32px);overflow-y:auto;border:1px solid var(--pb-line);border-top:3px solid var(--pb-accent);border-radius:8px;padding:18px;background:var(--pb-bg);box-shadow:none}
.pb-basket-heading{display:flex;align-items:center;justify-content:space-between;gap:12px}
#library-view .pb-basket h2{font-size:22px;margin:0}#library-view #close-basket{font-size:23px;border:0;padding:3px 9px;background:transparent}
#library-view .pb-basket .pb-small{font-size:14px}#library-view .pb-basket-item{font-size:16px;border-bottom:1px solid var(--pb-line);padding:10px 0}
#library-view .pb-basket-item b{font-size:16px;line-height:1.6}#library-view .pb-basket-controls{font-size:14px}#library-view .pb-basket-controls button{font-size:14px;padding:4px 8px}
#library-view .pb-setlabel{font-size:15px}#library-view .pb-setlabel input{font-size:16px}#library-view .pb-stack button{font-size:17px}
.pb-paper-filters .pb-paper-search{flex:1}.pb-paper-filters input{width:100%}.pb-paper-filters select{min-width:160px}
.pb-paper-count{display:flex;align-items:center;justify-content:space-between;margin:22px 0 14px;gap:14px}.pb-paper-count strong{font-size:18px;font-weight:600}.pb-paper-count>span{font-size:15px;color:var(--pb-muted)}
.pb-paper-columns,.pb-paper-row{display:grid;grid-template-columns:minmax(0,1fr) 175px 90px 135px;gap:24px;align-items:center;padding:0 22px}
.pb-paper-columns{height:42px;background:#eaf0f3;border:1px solid var(--pb-line);border-radius:8px 8px 0 0;font-size:14px;color:var(--pb-muted)}
#library-view #paper-list{display:block;margin:0;border:1px solid var(--pb-line);border-top:0;border-radius:0 0 8px 8px;background:var(--pb-bg);overflow:hidden}
.pb-paper-row{min-height:86px;border-bottom:1px solid var(--pb-line);padding-top:12px;padding-bottom:12px}.pb-paper-row:last-child{border-bottom:0}.pb-paper-row:hover{background:var(--pb-soft)}
#library-view .pb-paper-name h2{font-size:21px;line-height:1.45;margin:0 0 3px}
#library-view .pb-paper-name h2 button{padding:0;border:0;background:none;text-align:left;font-size:21px;line-height:1.45;font-weight:600;color:var(--pb-ink)}
.pb-paper-name>span{font-size:14px;color:var(--pb-muted)}.pb-paper-range,.pb-paper-size{font-size:17px;color:var(--pb-muted)}
#library-view .pb-paper-open{font-size:16px;padding:9px 13px;color:var(--pb-accent);background:transparent;border-color:#b9d4d4;white-space:nowrap}
.pb-pagination{display:flex;justify-content:flex-end;align-items:center;gap:16px;margin:18px 0;color:var(--pb-muted);font-size:15px}#library-view .pb-pagination button{font-size:16px;padding:8px 14px}
#library-view .pb-back{border:0;padding:4px 0;background:none;color:var(--pb-muted);font-size:17px;margin-bottom:14px}
.pb-detail-heading{padding:0 0 20px;display:flex;flex-direction:column;gap:16px}.pb-detail-heading p{font-size:15px;color:var(--pb-muted);margin:0 0 8px}
#library-view .pb-detail-heading h2{font-size:30px;line-height:1.4;margin:0}
.pb-detail-actions{display:flex;align-items:center;gap:10px;flex-wrap:wrap}#library-view .pb-detail-actions button{font-size:17px;padding:10px 16px}
.pb-paper-more{position:relative;font-size:16px}.pb-paper-more summary{cursor:pointer;padding:10px;color:var(--pb-muted)}.pb-paper-more[open]{border:1px solid var(--pb-line);border-radius:6px;background:var(--pb-bg)}
.pb-selection-bar{display:flex;align-items:center;gap:18px;position:sticky;top:8px;z-index:5;background:var(--pb-bg);border:1px solid var(--pb-line);border-left:3px solid var(--pb-accent);border-radius:6px;padding:12px 18px;margin-bottom:20px;box-shadow:0 3px 12px #18324709}
.pb-selection-bar label{display:flex;align-items:center;gap:10px;font-size:18px}.pb-selection-bar span{color:var(--pb-muted);font-size:16px;margin-right:auto}.pb-selection-bar input{width:20px;height:20px}
#library-view .pb-selection-bar button{font-size:17px;padding:8px 14px}
.pb-preview-question{padding:24px;background:var(--pb-bg);border:1px solid var(--pb-line);border-radius:8px;margin-bottom:20px;scroll-margin-top:90px}
.pb-preview-question>header{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:18px}
.pb-preview-question>header label{display:flex;align-items:center;gap:12px;cursor:pointer;flex-wrap:wrap}.pb-preview-question>header input{width:22px;height:22px}.pb-preview-question>header strong{font-size:22px}.pb-preview-question>header label span{font-size:14px;color:var(--pb-muted)}
.pb-preview-question>header>div{display:flex;gap:8px;flex-shrink:0}#library-view .pb-preview-question>header button{font-size:16px;padding:8px 12px}
.pb-preview-stem{white-space:pre-line;font-size:24px;line-height:1.75;margin:0 0 18px}
.pb-preview-figures{display:flex;flex-wrap:wrap;gap:14px;align-items:flex-start;margin-bottom:12px}.pb-preview-figures svg{max-width:500px}.pb-preview-figures img{max-height:300px;max-width:100%;height:auto;object-fit:contain}
#library-view .pb-preview-figures .pb-source-figure{max-width:100%;min-width:0;margin-bottom:0}.pb-preview-figures .pb-source-figure img{min-width:0}
.pb-preview-options{font-size:22px;line-height:1.7}.pb-preview-options b{font-size:16px;font-weight:500;color:var(--pb-muted)}.pb-preview-options p{margin:8px 0}.pb-preview-options p>span{color:var(--pb-accent);font-weight:600}
.pb-preview-question>footer{display:flex;justify-content:space-between;align-items:center;margin-top:20px;gap:15px;font-size:14px;color:var(--pb-muted)}#library-view .pb-preview-question>footer button{font-size:16px;padding:7px 12px}
.pb-preview-question>details{border-top:1px solid var(--pb-line);padding-top:14px;margin-top:14px;font-size:19px;line-height:1.7}.pb-preview-question>details summary{font-size:16px;color:var(--pb-muted);cursor:pointer}.pb-preview-question>details li{margin-bottom:10px}
@media(max-width:1450px){#library-view .pb-layout.with-basket{grid-template-columns:minmax(0,1fr) 310px;gap:18px}.pb-paper-columns,.pb-paper-row{grid-template-columns:minmax(0,1fr) 120px 60px 120px;gap:14px;padding-left:18px;padding-right:18px}#library-view .pb-filters{gap:12px}.with-basket .pb-preview-question>header label span{display:none}#library-view .pb-preview-question{padding:20px}.pb-preview-stem{font-size:22px}}
html[data-science-theme=dark] body:not(.pb-in-session):has(#practice-app){background:#111d29}
html[data-science-theme=dark] #library-view{--pb-accent:#46bdb7;--pb-ink:#e3edf5;--pb-muted:#a4b5c3;--pb-bg:#192a39;--pb-line:#314859;--pb-soft:#203c47}
html[data-science-theme=dark] #library-view .pb-chapter.active{background:#21464a;border-color:#386c6b;color:#8adecf}
html[data-science-theme=dark] #library-view .pb-paper-columns{background:#223646}html[data-science-theme=dark] #library-view .pb-tag{background:#293f50;color:#b8c9d6}html[data-science-theme=dark] #library-view .pb-tag.progress{background:#224b43;color:#8ddbc2}
html[data-science-theme=dark] #library-view #basket-count{background:#214b4e;color:#8adecf}html[data-science-theme=dark] #library-view button.pb-primary{background:#177e80;border-color:#268f90;color:#fff}html[data-science-theme=dark] #library-view .pb-favorite[aria-pressed=true]{background:#493b22;border-color:#806731;color:#f2d28a}

#library-view .pb-heading{padding:12px 0 12px}.pb-library-tabs{margin-bottom:12px}#library-view .pb-chapters{margin-bottom:10px}#library-view .pb-chapter{padding-top:8px;padding-bottom:8px}#library-view .pb-filters,#library-view .pb-paper-filters{padding-top:12px;padding-bottom:12px}#library-view .pb-listbar{margin-top:12px}
#library-view #basket-list{max-height:clamp(140px,32vh,350px);overflow:auto;overscroll-behavior:contain;padding-right:5px}#library-view .pb-basket .pb-stack{display:grid;grid-template-columns:1fr 1fr;gap:8px}#library-view #start-teach{grid-column:1/-1}.pb-saved-groups{font-size:16px;border-top:1px solid var(--pb-line);padding-top:12px}.pb-saved-groups summary{cursor:pointer;color:var(--pb-muted)}html[data-science-theme=dark] #library-view .pb-question .pb-goal{color:#72c9c3}
#library-view .pb-basket>p:first-of-type{display:none}#library-view #basket-list{max-height:clamp(120px,24vh,260px)}#library-view .pb-basket .pb-setlabel{margin-top:12px}

#practice-app .pb-answer-image{border-color:#9ac9c8;color:#087a80;background:#eef9f8;white-space:nowrap}.pb-preview-question>footer>div{display:flex;gap:8px;flex-wrap:wrap;justify-content:flex-end}

/* Local similar-question search: answer-free previews, with the current exercise preserved. */
#session-favorite{display:flex;gap:8px;align-items:center}
#similar-dialog{width:min(1100px,calc(100vw - 80px));max-width:none;height:min(880px,calc(100vh - 64px));max-height:none;padding:0;border:1px solid var(--pb-line);border-radius:18px;background:var(--pb-bg);color:var(--pb-ink);overflow:hidden}
#similar-dialog::backdrop{background:#091a31b8}
.pb-similar-head{display:flex;align-items:flex-start;gap:20px;padding:20px 24px;border-bottom:1px solid var(--pb-line);background:var(--pb-bg)}
#practice-app .pb-similar-head h2{font-size:26px;margin:0 0 6px;line-height:1.3}.pb-similar-head p{font-size:16px;margin:0;color:var(--pb-muted);line-height:1.6}.pb-similar-head>div{flex:1}#similar-close{flex-shrink:0}
.pb-similar-body{height:calc(100% - 112px);overflow:auto;overscroll-behavior:contain;padding:18px 24px 30px}
#similar-source{font-size:18px;font-weight:700;margin:0 0 8px}#similar-status{font-size:16px;color:var(--pb-accent);margin:8px 0 18px}
.pb-similar-card{border:1px solid var(--pb-line);border-radius:12px;padding:20px;margin-bottom:16px;background:var(--pb-bg)}
.pb-similar-cardhead{display:flex;align-items:baseline;justify-content:space-between;gap:14px}#practice-app .pb-similar-card h3{font-size:22px;line-height:1.5;margin:0 0 10px}.pb-similar-cardhead>span{font-size:15px;color:var(--pb-muted);white-space:nowrap}
.pb-similar-reasons{display:flex;flex-wrap:wrap;gap:6px}.pb-similar-reasons span{font-size:15px;border-radius:6px;padding:4px 9px;color:var(--pb-accent);background:var(--pb-soft)}
.pb-similar-excerpt{font-size:18px;line-height:1.7;margin:12px 0}.pb-similar-card details{border:0;padding:0;margin:10px 0}.pb-similar-card summary{font-size:17px;color:var(--pb-accent);cursor:pointer}.pb-similar-card details p{font-size:21px;line-height:1.7;white-space:pre-wrap}.pb-similar-card details svg{width:min(100%,480px);height:auto}
#practice-app .pb-similar-card .pb-source-figure{display:block;max-width:100%;margin:12px auto;background:white}.pb-similar-card img{max-width:100%;max-height:320px;object-fit:contain}.pb-similar-card footer{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:16px}.pb-similar-card footer>span{font-size:14px;color:var(--pb-muted)}.pb-similar-card footer>div{display:flex;gap:8px;flex-shrink:0}.pb-similar-practice{display:inline-flex;align-items:center;padding:8px 14px;border-radius:9px;background:var(--pb-accent);color:white!important;font-size:17px;text-decoration:none}
#practice-app #similar-dialog button{font-size:17px}#practice-app #similar-dialog .pb-source-figure span{display:block;font-size:15px}

#similar-dialog[open]{display:flex;flex-direction:column}.pb-similar-head{flex-shrink:0}.pb-similar-body{height:auto;flex:1;min-height:0}

html[data-science-theme=dark] #similar-status,html[data-science-theme=dark] .pb-similar-reasons span,html[data-science-theme=dark] .pb-similar-card summary{color:#94dcf0}html[data-science-theme=dark] .pb-similar-reasons span{background:#17394b}