@font-face{font-family:Playwrite;src:url('fonts/PlaywriteITModerna-Regular.ttf') format('truetype');font-display:swap}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:#f6f7f3;color:#243a39;font-family:Inter,ui-sans-serif,-apple-system,BlinkMacSystemFont,'Segoe UI',Arial,sans-serif;font-size:16px;line-height:1.55}button,input,select{font:inherit}button,a,input,summary{touch-action:manipulation}a{color:inherit;text-decoration:none}button{cursor:pointer}button:disabled,.disabled{opacity:.4;pointer-events:none}button,input,select{color:inherit}button{background:none;border:0}h1,h2,h3,p{margin:0}h1,h2,h3{line-height:1.2}button:focus-visible,a:focus-visible,summary:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #b17825;outline-offset:4px}[hidden]{display:none!important}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}.skip{position:fixed;top:-100px;left:15px;z-index:100;background:#fff;padding:12px}.skip:focus{top:10px}.topbar{height:84px;border-bottom:1px solid #e0e5df;display:flex;align-items:center;justify-content:space-between;gap:20px;padding:0 max(28px,calc((100% - 1180px)/2));background:#fff}.brand{display:flex;gap:12px;align-items:center;font-size:22px;font-weight:750;white-space:nowrap}.brand small{display:block;font-size:9px;letter-spacing:1.8px;font-weight:600;color:#71817d}.brandmark{display:grid;grid-template-columns:repeat(2,9px);gap:3px;transform:rotate(-8deg)}.brandmark i{width:9px;height:13px;border-radius:3px;background:#347d72}.brandmark i:nth-child(2){background:#d9b66b}.brandmark i:nth-child(3){background:#9b85b2}.topbar nav{display:flex;gap:12px}.navlink{padding:10px 16px;border-radius:8px;font-size:14px;font-weight:650}.navlink.active{background:#eaf2ed;color:#2b695f}.display-tools{display:flex;gap:5px}.icon-button{min-width:44px;min-height:44px;border:1px solid #dce3dd;border-radius:8px;background:#fff;font-weight:650}.display-tools .icon-button{border:0}main{max-width:1180px;margin:auto;padding:36px 28px 60px;min-height:calc(100vh - 168px)}.eyebrow{font-size:11px;letter-spacing:1.7px;font-weight:750;color:#5c7970}.hero{display:grid;grid-template-columns:1.2fr 1fr;gap:30px;align-items:center;padding:20px 0 38px}.hero h1{font-size:clamp(38px,4vw,58px);letter-spacing:-2.4px;margin:15px 0 20px;font-weight:700}.hero h1 em{font-family:Georgia,serif;font-weight:400;color:#447f70}.hero-copy>p:last-of-type{max-width:460px;color:#657872}.hero-stats{display:none}.hero-visual{max-width:430px;justify-self:end}.hero-visual svg{width:100%;max-height:220px}.visual-note{display:block;text-align:center;font-size:12px;color:#7a8b82}.dot{display:inline-block;width:6px;height:6px;background:#3e8d71;border-radius:50%;margin-right:6px}.section-head{display:flex;align-items:center;justify-content:space-between;gap:15px;margin:32px 0 20px}.section-head h2{font-size:23px}.button{display:inline-flex;justify-content:center;align-items:center;gap:12px;min-height:48px;padding:10px 20px;border-radius:9px;border:1px solid #dce3dc;font-size:15px;font-weight:650;background:#fff;white-space:nowrap}.button:hover{filter:brightness(.97)}.button.primary{background:#286e60;border-color:#286e60;color:#fff}.button.purple{background:#6f568d;color:#fff;border-color:#6f568d}.button.teal{background:#286e60;color:#fff}.button.quiet{background:#fff}.button.small{min-height:42px;padding:8px 15px;font-size:13px}.button.wide{width:100%}.search-row{display:flex;gap:12px;margin:20px 0}.search-wrap{display:flex;align-items:center;flex:1;background:#fff;border:1px solid #d4ded4;border-radius:9px;overflow:hidden}.search-icon{padding:0 14px;font-size:24px;color:#7b8d83}input[type=search]{width:100%;border:0;background:none;min-height:50px;padding:10px 14px 10px 0}.lesson-jump{display:flex;gap:6px}.lesson-jump input{width:100px;min-height:50px;background:#fff;border:1px solid #d4ded4;border-radius:8px;padding:10px}.topic-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.topic-card{position:relative;border:1px solid #dfe5db;border-radius:14px;padding:22px 24px;background:#fff;transition:transform .15s,border-color .15s}.topic-card:hover{border-color:var(--tone);transform:translateY(-2px)}.topic-number{font-size:10px;font-weight:700;letter-spacing:1.8px;color:var(--tone)}.topic-glyph{display:block;width:38px;height:38px;margin:24px 0 16px;color:var(--tone)}.topic-card h3{font-size:20px;margin:0 0 10px}.topic-card>p{font-size:13px;color:#738178;min-height:40px}.card-bottom{display:flex;justify-content:space-between;align-items:center;border-top:1px solid #edf0e9;margin-top:20px;padding-top:15px;gap:8px;font-size:11px;color:#6e7d73}.card-bottom b{font-size:21px;color:var(--tone)}.continue{background:#e8f0e9;border:1px solid #d6e2d6;border-radius:10px;padding:15px 20px;display:flex;align-items:center;justify-content:space-between;gap:20px}.continue p{font-size:10px;letter-spacing:1px}.continue strong{font-size:14px}.how{display:none}.crumb{font-size:12px;color:#73877b;display:flex;gap:12px;margin-bottom:25px}.topic-header h1{font-size:40px;letter-spacing:-1px;margin:15px 0}.topic-header>p:last-child{max-width:680px;color:#687d71}.catalog-controls{display:flex;align-items:center;justify-content:space-between;margin:20px 0;font-size:13px;color:#758477}.catalog-controls select{border:1px solid #d7e0d5;background:#fff;border-radius:8px;padding:10px 15px}.lesson-list{display:grid;gap:9px}.lesson-link{display:flex;align-items:center;gap:20px;background:#fff;border:1px solid #dce3d9;border-radius:10px;padding:18px 22px}.lesson-link:hover{border-color:var(--tone)}.lesson-id{color:var(--tone);background:var(--wash);display:grid;place-items:center;width:44px;height:44px;border-radius:10px;flex-shrink:0;font-weight:750}.lesson-link h3{font-size:16px}.lesson-link p{font-size:12px;color:#77867b;margin-top:7px}.lesson-link .arrow{margin-left:auto}.empty,.locked-page{padding:70px 10px;text-align:center}.empty p,.locked-page p{margin:20px 0}.locked-page h1{font-size:34px}.site-footer{border-top:1px solid #dfe5db;display:flex;justify-content:space-between;gap:20px;max-width:1124px;margin:auto;padding:22px 0;font-size:12px;color:#78877c}
/* The question is the centre of the screen. */
.in-reader{background:#f6f7f3}.in-reader .topbar{height:62px}.in-reader .brand{font-size:18px}.in-reader .brand small{display:none}.in-reader .site-footer{display:none}.in-reader main{padding-top:20px;padding-bottom:110px;max-width:1180px}.reader-toolbar{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:18px}.back-link{font-size:13px;font-weight:600;color:#63796c;min-height:44px;display:inline-flex;align-items:center}.reader-options{display:flex;gap:18px;align-items:center}.reader-options details{position:relative}.reader-options summary{list-style:none;cursor:pointer;min-height:44px;display:flex;align-items:center;gap:12px;font-size:13px;font-weight:600}.reader-options summary::-webkit-details-marker,.level-control summary::-webkit-details-marker{display:none}.question-picker nav{position:absolute;right:0;top:48px;width:280px;z-index:5;display:grid;grid-template-columns:repeat(5,1fr);gap:8px;padding:16px;background:#fff;border:1px solid #d4ded4;border-radius:12px;box-shadow:0 12px 32px #19352614}.question-picker nav a{display:grid;place-items:center;height:44px;border:1px solid #dce4da;border-radius:8px}.question-picker [aria-current]{background:#286e60;color:#fff;border-color:#286e60}.settings-content{position:absolute;right:0;top:48px;z-index:6;width:200px;background:#fff;border:1px solid #d4ded4;border-radius:12px;padding:8px;box-shadow:0 12px 32px #19352614}.settings-content button{display:block;text-align:left;width:100%;padding:12px;font-size:14px;border-radius:6px}.settings-content button:hover{background:#edf3ed}.reader-heading{display:flex;align-items:baseline;gap:16px;margin-bottom:18px}.worksheet-number{font-size:10px;font-weight:750;letter-spacing:1.6px;color:#6e8274;white-space:nowrap}.reader-heading h1{font-size:18px;font-weight:600;color:#4e6558;line-height:1.45}.level-control{border-top:1px solid #dce4d9;border-bottom:1px solid #dce4d9;margin-bottom:28px;font-size:12px}.level-control>summary{display:flex;justify-content:space-between;gap:16px;cursor:pointer;list-style:none;min-height:46px;align-items:center;color:#687c6f}.level-control strong{font-weight:600;color:#345c4d}.change-label{color:#2e6c5b;font-weight:650;white-space:nowrap}.support-panel{max-width:560px;margin:4px auto 20px;padding:12px 18px;border-radius:12px;background:#eaf1e8}.support-panel>p{font-size:13px;margin-bottom:14px}.support-panel input{display:block;width:100%;accent-color:#347a64;height:30px;margin:0}.slider-labels{display:flex;justify-content:space-between;gap:8px}.slider-labels button{max-width:31%;padding:8px 0;min-height:44px;font-size:12px;color:#728371}.slider-labels .active{color:#286e60;font-weight:750}.support-panel .level-instruction{font-size:11px;color:#758473;margin:10px 0 0}.question-card{background:#fff;border:1px solid #e0e6dd;border-radius:18px;padding:36px}.question-layout{display:grid;grid-template-columns:1fr 1.05fr;gap:42px;align-items:start}.question-kicker{display:flex;gap:14px;align-items:center;margin-bottom:20px;font-size:11px;letter-spacing:1.1px;font-weight:750;color:#6a7f70}.skill-tag{border-radius:5px;background:#f1f4ed;padding:4px 8px;font-size:10px;letter-spacing:0;color:#70806e;font-weight:600}.question-prompt{font-size:clamp(24px,2.6vw,32px);font-weight:650;letter-spacing:-.55px;line-height:1.48;overflow-wrap:anywhere;outline:none}.question-prompt:focus-visible{outline:none}.book-reminder{font-size:13px;line-height:1.6;color:#778371;margin-top:24px;display:flex;align-items:flex-start;gap:8px}.book-reminder svg{width:16px;height:20px;flex-shrink:0;fill:none;stroke:currentColor;stroke-width:1.4}.read-button{display:inline-flex;align-items:center;gap:8px;min-height:44px;font-size:12px;color:#597465;margin-top:8px;padding:0}.read-button svg{width:17px;height:17px;fill:none;stroke:currentColor;stroke-width:1.5}.model-panel{background:#f1f6ef;border:1px solid #dae6d7;border-radius:13px;overflow:hidden}.model-heading{display:flex;align-items:center;justify-content:space-between;padding:8px 16px;gap:12px;color:#4e735e;font-size:11px;font-weight:650;border-bottom:1px solid #dfe9dc}.model-heading button{min-height:36px;font-size:11px;padding:0;white-space:nowrap;color:#52745d}.model-wrap{padding:20px 18px}.math-model{display:block;width:100%;height:auto;max-height:none;overflow:visible}.model-scroll{max-width:100%;overflow:auto}.model-scroll .math-model{min-width:var(--diagram-width,0px);max-width:100%}.model-note{font-size:13px;line-height:1.55;color:#5b725e;text-align:center;margin-top:16px}.model-note:first-child{margin-top:0;margin-bottom:16px}.guided-help{margin-top:12px;border:1px solid #e7e3d0;border-radius:10px;background:#fdfbf4;overflow:hidden}.help-button{width:100%;display:flex;align-items:center;text-align:left;gap:10px;min-height:49px;padding:10px 15px;font-weight:600;color:#7b662e;font-size:13px}.help-button>span:last-child{margin-left:auto}.help-icon{width:20px;height:20px;border:1px solid #b5a573;border-radius:50%;display:grid;place-items:center;font-size:11px}.hint-panel{padding:0 17px 16px}.step-list{list-style:none;counter-reset:hint;padding:0;margin:0}.step-list li{counter-increment:hint;position:relative;padding:10px 0 10px 29px;font-size:14px;line-height:1.6;color:#685a37}.step-list li:before{content:counter(hint);position:absolute;left:0;top:13px;display:grid;place-items:center;width:18px;height:18px;border-radius:50%;background:#e8dfbb;color:#746031;font-size:10px;font-weight:750}.next-hint{font-size:12px;color:#79612a;min-height:40px;padding:6px 0;margin-left:29px;text-decoration:underline;text-underline-offset:4px}.reader-footer{position:fixed;left:0;right:0;bottom:0;background:#ffffffee;border-top:1px solid #dbe3d6;z-index:8;backdrop-filter:blur(14px);padding:12px 24px max(12px,env(safe-area-inset-bottom))}.reader-footer>div{max-width:1060px;margin:auto;display:flex;justify-content:space-between;align-items:center;gap:20px}.reader-footer .button{min-width:130px;min-height:48px}.reader-footer .quiet{background:none;border-color:transparent}.footer-count{font-size:15px;font-weight:700;letter-spacing:1px;color:#53765f}.footer-count span{font-weight:400;color:#8e9a8b}.challenge-intro{font-size:13px;color:#7b8174;margin:0 0 24px}.finish-page{max-width:600px;text-align:center;margin:50px auto}.finish-mark{width:64px;height:64px;display:grid;place-items:center;margin:0 auto 25px;background:#e1eee2;border-radius:50%;color:#407658;font-size:28px}.finish-page h1{font-size:38px;letter-spacing:-1px;margin:14px 0 18px}.finish-page>p:not(.eyebrow){color:#71816f;max-width:430px;margin:auto}.finish-actions{display:grid;gap:12px;margin:32px auto;max-width:360px}.finish-page .back-link{display:inline-flex}.large-text .question-prompt{font-size:clamp(29px,3vw,39px)}.large-text .solution{font-size:21px}.print-heading{display:none}.answer-head h1{font-size:36px;margin:15px 0}.answer-head>p:last-child{color:#70806f}.answers-notice{margin:25px 0;color:#647c65;font-size:14px}.answer-actions{display:flex;gap:12px;margin:24px 0}.answer-row{background:#fff;border:1px solid #dee6da;border-radius:12px;padding:26px;margin:16px 0}.answer-row h2{font-size:13px;color:#74846c;margin-bottom:12px}.answer-question{font-size:16px;line-height:1.7}.solution{font-size:18px;font-weight:600;color:#337354;background:#edf5e9;padding:18px;border-radius:8px;margin-top:18px;white-space:pre-line}.loading{text-align:center;padding:100px}.spinner{display:inline-block;width:20px;height:20px;border:2px solid #b5c5b2;border-top-color:#2f7758;border-radius:50%;animation:spin 1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}dialog{width:min(480px,calc(100% - 28px));border:1px solid #d4dfd0;border-radius:18px;padding:28px;color:#2b4435;box-shadow:0 24px 70px #122f2440}dialog::backdrop{background:#18352880;backdrop-filter:blur(3px)}.dialog-top{display:flex;align-items:center;justify-content:space-between;margin-bottom:20px}.dialog-top .icon-button{border:0;font-size:24px}.lock-symbol{font-size:25px}dialog h2{font-size:25px;margin:12px 0 16px}dialog p{color:#71806c;font-size:14px;margin-bottom:20px}dialog label{font-size:13px;font-weight:650;display:block}#answer-code{display:block;width:100%;font-size:27px;letter-spacing:7px;min-height:60px;padding:12px;margin:8px 0;border:1px solid #b8c9b1;border-radius:8px}#gate-error{color:#a34239;margin:9px 0 14px;font-size:13px}.model-dialog{width:min(850px,calc(100% - 28px));max-height:92vh;overflow:auto}.model-dialog>p{display:none}#large-model{background:#f2f7ef;padding:30px;border-radius:12px}.toast{position:fixed;bottom:90px;left:50%;transform:translateX(-50%);max-width:90%;padding:12px 20px;background:#254534;color:#fff;border-radius:10px;opacity:0;pointer-events:none;z-index:30;font-size:13px}.toast.show{opacity:1}
@media(min-width:1600px){.in-reader main{max-width:1400px}.question-card{padding:48px}.question-prompt{font-size:36px}.reader-footer>div{max-width:1280px}.model-wrap{padding:28px}.in-reader .question-layout{gap:60px}}
@media(max-width:900px){.topbar{padding:0 24px}.topic-grid{grid-template-columns:repeat(2,1fr)}.hero-visual{max-width:320px}.question-layout{gap:28px}.question-card{padding:28px}.reader-heading{display:block}.reader-heading h1{margin-top:4px;font-size:16px}.site-footer{margin:0 28px}.model-wrap{padding:18px 14px}}
@media(max-width:700px){.topbar{height:68px;padding:0 18px;gap:12px}.brand{font-size:18px}.brand small{font-size:7px}.topbar nav{gap:0}.navlink{font-size:11px;padding:9px}.display-tools{display:none}main{padding:25px 18px 40px}.hero{grid-template-columns:1fr;padding:0 0 12px;gap:0}.hero h1{font-size:43px;margin:10px 0 18px}.hero-visual{display:none}.hero-copy>p:last-of-type{font-size:14px}.section-head{margin:24px 0 15px}.section-head h2{font-size:20px}.button.small{font-size:11px;padding:8px 10px}.search-row{flex-wrap:wrap}.lesson-jump{width:100%}.lesson-jump input{flex:1}.topic-grid{gap:10px}.topic-card{padding:18px 15px}.topic-card h3{font-size:16px}.topic-glyph{margin:18px 0 12px;width:31px;height:31px}.topic-card>p{font-size:11px;min-height:53px}.card-bottom{font-size:10px;align-items:flex-start}.card-bottom b{font-size:18px}.continue{padding:14px;gap:12px;align-items:flex-start}.continue strong{font-size:12px}.continue .button{margin-top:10px}.topic-header h1{font-size:30px}.topic-header>p:last-child{font-size:14px}.lesson-link{padding:14px;gap:13px}.lesson-link h3{font-size:14px}.lesson-link p{font-size:11px}.lesson-id{width:38px;height:38px;font-size:14px}.site-footer{margin:0 18px;display:block;text-align:center;font-size:11px}.site-footer span{display:block}.in-reader .topbar{height:54px}.in-reader .topbar nav{display:none}.in-reader .display-tools{display:flex}.in-reader .display-tools #fullscreen{display:none}.in-reader .brandmark{grid-template-columns:repeat(2,7px);gap:2px}.in-reader .brandmark i{width:7px;height:10px}.in-reader .brand{font-size:16px;gap:8px}.in-reader .icon-button{min-height:40px;font-size:13px}.in-reader main{padding:10px 16px 98px}.reader-toolbar{margin-bottom:7px}.reader-options{gap:15px}.reader-options summary,.back-link{font-size:11px}.reader-heading{margin-bottom:12px}.worksheet-number{font-size:9px;letter-spacing:1.4px}.reader-heading h1{font-size:14px;line-height:1.5}.level-control{margin-bottom:18px;font-size:11px}.level-control>summary{min-height:40px}.question-card{border-radius:12px;padding:22px 18px}.question-layout{grid-template-columns:1fr;gap:20px}.question-kicker{font-size:10px;margin-bottom:12px}.question-prompt{font-size:23px;letter-spacing:-.45px;line-height:1.45}.large-text .question-prompt{font-size:29px}.book-reminder{font-size:11px;margin-top:14px;gap:6px}.book-reminder svg{width:13px;height:17px}.read-button{font-size:11px;min-height:34px;margin-top:4px}.read-button svg{width:14px;height:14px}.model-heading{padding:6px 13px;font-size:10px}.model-heading button{font-size:10px;min-height:30px}.model-wrap{padding:17px 12px}.model-note{font-size:12px;margin-top:13px}.help-button{min-height:44px;font-size:12px;padding:9px 13px}.guided-help{margin-top:10px}.reader-footer{padding:9px 16px max(9px,env(safe-area-inset-bottom))}.reader-footer .button{min-width:104px;min-height:46px;font-size:14px}.reader-footer>div{gap:12px}.footer-count{font-size:13px}.finish-page{margin:25px auto}.finish-page h1{font-size:31px}.finish-page>p{font-size:14px}.answer-head h1{font-size:27px}.answer-actions{flex-wrap:wrap}.answer-row{padding:18px}.solution{padding:14px;font-size:16px}.question-picker nav{right:-62px}.model-dialog{padding:18px}#large-model{padding:20px 12px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;animation:none!important;transition:none!important}}
@media print{body{background:#fff;font-size:11pt}.topbar,.site-footer,.reader-toolbar,.level-control,.reader-footer,.read-button,.guided-help,.model-heading button,.answer-actions,.answers-notice,.toast,.skip{display:none!important}main,.in-reader main{padding:0;max-width:none}.question-card{break-inside:avoid;page-break-inside:avoid;padding:18px;margin:16px 0;border-color:#bbb}.question-layout{display:grid;grid-template-columns:1fr 1fr;gap:20px}.question-prompt{font-size:15pt}.book-reminder{font-size:9pt}.model-heading{font-size:9pt}.model-wrap{padding:12px}.reader-heading h1{font-size:18pt}.answer-row{break-inside:avoid}.solution{background:#fff;border:1px solid #aaa}.print-heading{display:block}.math-model{max-height:250px}.question-kicker{font-size:9pt}.model-note{font-size:9pt}}
/* Responsive mathematical representations; text never shrinks with an SVG. */
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/* Readable multi-part investigations, keeping the original worksheet type size. */
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