@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&family=Heebo:wght@400;500;600;700;800&family=Outfit:wght@400;500;600;700;800&display=swap');
:root{--ink:#29243c;--muted:#797487;--purple:#6b43d9;--purple-dark:#5632b5;--lime:#d9f3ac;--paper:#f7f7fa;--line:#e8e6ee}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:'DM Sans',sans-serif;font-size:16px}button,input,select{font:inherit}button,a,select{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:focus-visible,a:focus-visible,select:focus-visible{outline:3px solid #9b79ed;outline-offset:4px}button{border:0}button:disabled{cursor:default}a{color:inherit;text-decoration:none}.header{height:100px;border-bottom:1px solid var(--line);display:flex;align-items:center;gap:55px;padding:0 6%;background:#fff}.brand{display:flex;align-items:center;font-family:Outfit,sans-serif;font-size:26px;font-weight:700;letter-spacing:-1.1px;white-space:nowrap}.brand>span:not(.brand-mark):not(.brand-dot){color:var(--purple)}.brand-mark{width:37px;height:37px;border-radius:11px;background:var(--purple);color:var(--lime);display:grid;place-items:center;font-size:32px;margin-right:10px;transform:rotate(-8deg);font-weight:500}.brand-dot{font-size:11px;align-self:flex-start;margin-top:7px;margin-left:3px}.header nav{display:flex;gap:12px}.nav-button{background:none;color:var(--muted);padding:12px 17px;border-radius:10px;font-size:14px;font-weight:600;white-space:nowrap}.nav-button.active{background:#f0ebfc;color:var(--purple)}.header-note{margin-left:auto;font-size:12px;color:var(--muted);white-space:nowrap}.tiny-star{color:var(--purple);font-size:21px;vertical-align:middle;margin-right:8px}main{max-width:1180px;margin:0 auto;padding:46px 35px 0}.page-heading{display:flex;justify-content:space-between;align-items:center;margin-bottom:31px}.eyebrow{font-size:11px;font-weight:700;letter-spacing:2px;color:var(--purple)}h1,h2,h3{font-family:Outfit,sans-serif}h1{font-size:40px;letter-spacing:-1.5px;margin:12px 0 10px;font-weight:600}.page-heading p{color:var(--muted);font-size:15px;margin:0}.heading-sticker{margin-right:22px;transform:rotate(9deg);font-size:15px;line-height:1.1;font-family:Outfit;font-weight:600;position:relative;padding-right:38px}.heading-sticker span{font-size:57px;position:absolute;right:-23px;top:-8px;color:var(--purple)}.workspace{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:24px}.practice-card{background:white;border:1px solid var(--line);border-radius:22px;padding:26px 32px 0;overflow:hidden;box-shadow:0 5px 20px #29243c03}.card-top{display:flex;align-items:center;justify-content:space-between}.pill{display:flex;align-items:center;gap:7px;font-size:10px;font-weight:700;letter-spacing:1px;background:#f4f2fa;border-radius:20px;padding:8px 11px;color:#625879}.live-dot{width:6px;height:6px;background:var(--purple);border-radius:50%}.question-count{font-size:12px;color:var(--muted)}.round-progress{display:flex;gap:6px;margin-top:16px}.round-progress span{height:4px;flex:1;border-radius:5px;background:#eeebf5}.round-progress span.current{background:#b59cec}.round-progress span.done{background:var(--purple)}.challenge-heading{text-align:center;margin-top:28px}.challenge-heading h2{font-size:26px;font-weight:500;margin:0 0 8px;letter-spacing:-.6px}.challenge-heading p{font-size:13px;color:var(--muted);margin:0}.triangle-stage{height:251px;position:relative;max-width:440px;margin:9px auto 0}.connections{width:100%;height:100%;position:absolute;inset:0;overflow:visible}.connections path{stroke:#e7e0f6;stroke-width:2;fill:none;stroke-linejoin:round}.connections .connection-dash{stroke:var(--purple);stroke-dasharray:4 8;stroke-width:1.5;opacity:.22}.node{width:84px;height:84px;display:grid;place-items:center;position:absolute;border-radius:50%;font-family:Outfit;font-size:36px;font-weight:600;box-shadow:0 0 0 8px white;z-index:1}.node-product{left:calc(50% - 42px);top:14px;background:var(--purple);color:white}.node-left{left:calc(20% - 42px);top:162px;background:var(--lime);color:#3b5226}.node-right{left:calc(80% - 42px);top:162px;background:var(--lime);color:#3b5226}.node.missing{background:#fff;border:2px dashed #a38ad8;color:var(--purple)}.node.solved{background:var(--lime);border:2px solid #b9d68c;color:#3b5226}.edge-label{position:absolute;z-index:2;background:white;border-radius:50%;width:28px;height:28px;display:grid;place-items:center;color:#a28ac9;font-size:21px}.edge-left{left:31%;top:121px}.edge-right{right:31%;top:121px}.edge-bottom{left:calc(50% - 14px);top:190px}.product-caption{position:absolute;top:46px;left:calc(50% + 57px);font-size:11px;color:var(--muted)}.equation{display:flex;align-items:center;justify-content:center;gap:20px;font-family:Outfit;font-size:29px;margin:22px 0 20px}.equation span{color:#a9a3b7;font-weight:400}.equation .blank{color:var(--purple);border-bottom:2px solid #d6c9f3;min-width:35px;text-align:center}.answer-row{display:flex;gap:12px;max-width:390px;margin:auto}.answer-row input{width:0;flex:1;border:1px solid #ded9e8;border-radius:11px;padding:15px 17px;background:#faf9fc;text-align:center;font-size:16px;outline:none}.answer-row input:focus{border-color:var(--purple);box-shadow:0 0 0 3px #6b43d915}.answer-row input::placeholder{color:#a39baa;font-size:14px}.primary-button{background:var(--purple);color:#fff;border-radius:11px;padding:15px 22px;font-size:14px;font-weight:600;display:inline-flex;gap:20px;align-items:center;justify-content:center}.primary-button:hover{background:var(--purple-dark)}.primary-button span{font-size:18px}.hint-button{display:block;background:none;color:var(--muted);font-size:12px;margin:0 auto 22px;padding:9px}.hint-button span{font-size:19px;vertical-align:middle;margin-right:5px;color:#9e90b7}.feedback{font-size:14px;text-align:center;min-height:12px;line-height:1.5;margin:9px 0 1px}.feedback:not(:empty){padding:5px 10px 7px}.feedback.success{color:#4a672d}.feedback.retry{color:#a95a2e}.card-bottom{border-top:1px solid var(--line);margin:0 -32px;padding:16px 25px;display:flex;justify-content:space-between;color:#928c9e;font-size:10px;background:#fdfcfe}.mini-loop{font-size:15px;vertical-align:middle;margin-right:5px}.sidebar{display:flex;flex-direction:column;gap:20px}.connection-card{background:#eeebf8;border:1px solid #e7e1f4;border-radius:22px;padding:25px}.section-label{display:flex;justify-content:space-between;font-size:10px;letter-spacing:1.4px;font-weight:700;color:#817196}.section-label span{font-size:20px;margin-top:-5px}.connection-card h2{font-size:28px;font-weight:500;line-height:1.15;letter-spacing:-.6px;margin:24px 0 12px}.connection-card>p{font-size:13px;color:#82768f;line-height:1.7}.example-equations{margin:23px 0 19px;display:flex;flex-direction:column;gap:9px}.example-equations>div{display:flex;align-items:center;justify-content:center;gap:15px;border-radius:10px;background:#ffffffba;padding:9px;font-family:Outfit;font-size:20px}.example-equations span{color:#afa4bf;font-size:17px}.example-equations b{font-weight:500;min-width:18px;text-align:center}.example-equations b.whole{color:var(--purple)}.connection-note{border-top:1px solid #ded6ed;padding-top:18px;display:flex;gap:13px;align-items:center}.connection-note>span{font-size:34px;color:var(--purple)}.connection-note p{font-size:12px;line-height:1.8;margin:0;color:#82768f}.connection-note strong{font-weight:600;color:#5f4c7a}.settings-card{padding:20px 22px;border:1px solid var(--line);border-radius:16px;background:white}.settings-card label{display:block;font-size:13px;font-weight:600;margin-bottom:12px}.settings-card select{width:100%;background:#faf9fc;border:1px solid var(--line);border-radius:8px;padding:11px 8px;color:#685b80;font-size:12px}.settings-card p{font-size:11px;margin:10px 0 0;color:var(--muted)}.bottom-note{display:flex;gap:16px;align-items:center;padding:28px 6px}.note-symbol{color:#9886b6;font-size:30px}.bottom-note strong{font-size:13px;font-weight:600}.bottom-note p{font-size:12px;color:var(--muted);margin:6px 0 0}.bottom-tag{margin-left:auto;font-size:10px;letter-spacing:1.5px;color:#968b9f;border:1px solid #ded9e8;border-radius:6px;padding:7px 10px;transform:rotate(-4deg);white-space:nowrap}footer{max-width:1110px;margin:0 auto;padding:21px 6px;border-top:1px solid var(--line);display:flex;justify-content:space-between;font-size:11px;color:#9a93a5}.footer-star{color:var(--purple);margin-left:8px}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}[hidden]{display:none!important}.alternate-view{background:white;padding:32px;border:1px solid var(--line);border-radius:22px;min-height:480px}.explore-controls{display:flex;align-items:center;justify-content:center;gap:25px}.explore-controls label{font-size:14px;color:var(--muted);display:flex;flex-direction:column;gap:8px}.explore-controls select{padding:12px 25px;border:1px solid var(--line);border-radius:10px;font-size:22px;color:var(--purple);background:#f7f4fc}.explore-controls>span{font-size:30px;color:var(--purple);margin-top:22px}.explore-content{display:grid;grid-template-columns:1fr 1fr;gap:50px;margin-top:30px;align-items:center;text-align:center}.explore-family{display:flex;gap:14px;justify-content:center}.explore-family b{border-radius:50%;width:70px;height:70px;background:var(--lime);display:grid;place-items:center;font-size:28px;font-family:Outfit}.explore-family b:last-child{background:var(--purple);color:white}.explore-content h2{font-size:20px;font-weight:500}.dot-array{display:grid;gap:7px;justify-content:center;margin:20px auto;width:max-content}.dot-array span{width:14px;height:14px;border-radius:50%;background:var(--purple)}.dot-array span.alternate{background:#ad91e5}.explore-content p,.explore-tip{font-size:14px;color:var(--muted);line-height:1.6}.explore-equations{display:flex;flex-direction:column;gap:12px}.explore-equations div{padding:18px;background:#f3effb;border-radius:12px;font-family:Outfit;font-size:28px}.explore-tip{text-align:center;border-top:1px solid var(--line);padding-top:20px;margin-top:28px}.progress-intro{text-align:center}.large-star{font-size:45px;color:var(--purple)}.progress-intro h2{font-size:28px;margin:8px 0}.progress-intro p,.progress-explanation{color:var(--muted);font-size:14px}.stats-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:15px;margin:30px 0}.stat{background:#f4f0fb;border-radius:14px;text-align:center;padding:20px}.stat strong{font-size:35px;display:block;font-family:Outfit;color:var(--purple);margin-bottom:5px}.stat span{font-size:13px}.family-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(140px,1fr));gap:12px;margin:20px 0 28px}.family-tile{border:1px solid var(--line);border-radius:12px;padding:16px;text-align:center}.family-tile strong{display:block;font-family:Outfit;font-size:21px}.family-tile small{font-size:12px;display:block;color:var(--muted);margin-top:6px}.empty-progress{grid-column:1/-1;padding:20px;border-radius:10px;background:#f7f5fc;color:var(--muted);font-size:14px}.round-summary{text-align:center;padding:15px 10px 35px}.round-summary .large-star{display:block}.round-summary h2{font-size:30px}.round-summary p{color:var(--muted);line-height:1.6}.round-summary .primary-button{margin-top:15px}.round-summary .review{background:#f2eff9;border-radius:12px;padding:14px}.round-summary .review strong{color:var(--purple)}
@media(min-width:1450px){main{padding-top:60px}.header{padding:0 max(6%,calc((100vw - 1230px)/2))}.practice-card{padding-top:30px}.triangle-stage{margin-top:16px}.challenge-heading{margin-top:32px}}
@media(max-width:1050px){.header{gap:25px;padding:0 30px}.header-note{display:none}.header nav{margin-left:auto}.workspace{grid-template-columns:minmax(0,1fr) 270px}.connection-card{padding:22px}h1{font-size:35px}}
@media(max-width:740px){.header{height:auto;min-height:112px;flex-wrap:wrap;padding:19px 20px 12px;gap:16px}.brand{font-size:23px}.brand-mark{width:32px;height:32px}.header nav{width:100%;margin:0;justify-content:space-between;gap:4px}.nav-button{padding:10px 14px;font-size:13px}.header-note{display:none}main{padding:28px 18px 0}.eyebrow{font-size:10px;letter-spacing:1.5px}h1{font-size:29px;letter-spacing:-1px;margin-top:9px}.page-heading p{font-size:14px;line-height:1.6;max-width:300px}.heading-sticker{display:none}.page-heading{margin-bottom:22px}.workspace{display:flex;flex-direction:column;gap:18px}.practice-card{padding:22px 18px 0;border-radius:18px}.pill{font-size:9px;letter-spacing:.5px}.question-count{font-size:11px}.challenge-heading{margin-top:24px}.challenge-heading h2{font-size:24px}.challenge-heading p{font-size:12px;line-height:1.6;max-width:280px;margin:auto}.triangle-stage{height:239px;margin-top:15px}.connections{height:235px}.node{width:72px;height:72px;font-size:32px}.node-product{left:calc(50% - 36px);top:17px}.node-left{left:calc(20% - 36px);top:159px}.node-right{left:calc(80% - 36px);top:159px}.edge-left{left:29%;top:115px}.edge-right{right:29%;top:115px}.edge-bottom{top:185px}.product-caption{left:calc(50% + 49px);font-size:10px}.equation{margin:15px 0 20px;font-size:28px}.answer-row{gap:9px}.primary-button{padding:15px 16px;gap:12px}.answer-row input{padding:14px 8px;min-width:80px}.card-bottom{margin:0 -18px;padding:14px 16px;font-size:9px;gap:12px}.sidebar{gap:16px}.connection-card{padding:23px}.connection-card h2{margin-top:16px;font-size:26px}.connection-card h2 br{display:none}.connection-card>p{margin:8px 0}.desktop-break{display:none}.example-equations{display:grid;grid-template-columns:1fr 1fr;gap:9px;margin:20px 0}.example-equations>div{gap:9px;font-size:19px;padding:12px 5px}.connection-note{padding-top:12px}.connection-note p br{display:none}.connection-note p strong{margin-left:3px}.settings-card select{font-size:14px;padding:13px 10px}.settings-card label{font-size:14px}.settings-card p{font-size:12px}.bottom-note{padding:25px 0;gap:10px}.bottom-note strong{font-size:12px}.bottom-note p{font-size:11px;line-height:1.6}.bottom-tag{display:none}.note-symbol{font-size:26px}footer{margin:0 18px;padding:18px 0;font-size:10px;gap:20px;line-height:1.5}.alternate-view{padding:22px 18px;min-height:0}.explore-content{grid-template-columns:1fr;gap:20px}.explore-controls{gap:15px}.explore-controls select{padding:10px 20px}.explore-equations{display:grid;grid-template-columns:1fr 1fr;gap:9px}.explore-equations div{font-size:20px;padding:15px 5px}.stats-grid{gap:8px}.stat{padding:16px 7px}.stat strong{font-size:28px}.stat span{font-size:11px}.family-grid{grid-template-columns:repeat(2,1fr)}}
@media(prefers-reduced-motion:no-preference){.node{transition:background .2s,border .2s;}.primary-button{transition:background .15s}.node.solved{animation:pop .3s ease-out}@keyframes pop{50%{transform:scale(1.12)}}}

/* Hebrew layouts mirror the reading order; mathematical expressions stay LTR. */
.language-button{background:white;border:1px solid var(--line);border-radius:9px;padding:9px 12px;color:var(--purple);font-size:14px;white-space:nowrap;min-height:40px}
.header{gap:26px}.header-note{white-space:normal;line-height:1.5}
[dir="rtl"] body,[dir="rtl"] button,[dir="rtl"] input,[dir="rtl"] select{font-family:'Heebo','DM Sans',sans-serif}
[dir="rtl"] h1,[dir="rtl"] h2,[dir="rtl"] h3{font-family:'Heebo',sans-serif;letter-spacing:0}
[dir="rtl"] .brand{direction:ltr;margin-left:0;margin-right:0;font-family:Outfit,sans-serif}
[dir="rtl"] .header-note,[dir="rtl"] .bottom-tag{margin-left:0;margin-right:auto}
[dir="rtl"] .heading-sticker{margin-right:0;margin-left:22px;font-family:'Heebo',sans-serif}
[dir="rtl"] .eyebrow,[dir="rtl"] .section-label,[dir="rtl"] .pill{letter-spacing:0}
[dir="rtl"] .connection-card h2{line-height:1.4;font-size:26px}
[dir="rtl"] .triangle-stage,[dir="rtl"] .equation,[dir="rtl"] .example-equations>div,[dir="rtl"] .explore-equations>div,[dir="rtl"] .explore-family,[dir="rtl"] .family-tile strong,[dir="rtl"] #answer,[dir="rtl"] .round-summary .review{direction:ltr;unicode-bidi:isolate}
[dir="rtl"] .round-summary .review{direction:rtl}
[dir="rtl"] .round-summary .review strong{display:block;direction:ltr;unicode-bidi:isolate}
[dir="rtl"] .nav-button{font-size:14px}
@media(max-width:1050px){[dir="rtl"] .header nav{margin-left:0;margin-right:auto}.header{gap:18px}.header-note{display:none}}
@media(max-width:740px){.header{position:relative;padding-top:18px;gap:12px}.header nav{order:3}.language-button{margin-inline-start:auto;padding:8px 11px}.header nav,[dir="rtl"] .header nav{margin:0}.header .nav-button{font-size:13px;padding:10px 9px}.brand{font-size:22px}.page-heading p{max-width:none}[dir="rtl"] h1{font-size:27px;line-height:1.4}[dir="rtl"] .challenge-heading h2{font-size:23px}[dir="rtl"] .connection-card h2{font-size:23px}[dir="rtl"] .card-bottom{font-size:10px}.header-note{display:none}}

#challenge-title{scroll-margin-top:24px}
#challenge-title:focus{outline:none}

.focus-chooser{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:8px}.focus-chooser label{font-size:16px;font-weight:600}.focus-chooser select{min-width:76px;min-height:44px;padding:8px 14px;border:1px solid #d6c9f3;border-radius:10px;background:#f4efff;color:var(--purple);font-size:20px}.focus-note{font-size:13px;color:var(--muted);margin:0 0 22px;line-height:1.6}@media(max-width:740px){.focus-chooser label{font-size:14px}.focus-note{font-size:12px}}

/* Explanation card at the top of the quiz */
.intro-card{grid-column:1/-1;display:grid;grid-template-columns:1fr auto;align-items:center;gap:8px 40px;padding:24px 28px}
.intro-card .section-label{grid-column:1/-1}
.intro-card .intro-text{grid-column:1;display:flex;flex-direction:column;gap:12px}
.intro-card h2{margin:0;font-size:24px}
.intro-card .intro-text p{margin:0;max-width:460px}
.intro-card .example-caption{font-size:13px;font-weight:600;color:#5f4c7a}
.intro-card .example-equations{grid-column:2;grid-row:2;margin:0;min-width:220px}
.intro-card .example-equations b{min-width:auto;font-size:16px;color:#5f4c7a}
.intro-card .example-equations b.whole{color:var(--purple)}
.intro-card .example-equations span{font-size:15px}
.intro-card .connection-note{grid-column:1/-1;border-top:1px solid #ded6ed}
@media(max-width:900px){.intro-card{grid-template-columns:1fr}.intro-card .example-equations{grid-column:1;grid-row:auto;display:grid;grid-template-columns:1fr 1fr}}

/* Auto-advance toggle */
.toggle-row{display:flex;align-items:center;justify-content:space-between;gap:14px;margin-bottom:0!important;cursor:pointer}
.toggle-text{font-size:13px;font-weight:600;line-height:1.4}
.toggle-switch{position:relative;flex:none;width:44px;height:26px}
.toggle-switch input{position:absolute;opacity:0;width:100%;height:100%;margin:0;cursor:pointer}
.toggle-track{position:absolute;inset:0;background:#d9d3e6;border-radius:20px;transition:background .18s}
.toggle-track::after{content:"";position:absolute;top:3px;left:3px;width:20px;height:20px;border-radius:50%;background:#fff;box-shadow:0 1px 2px #29243c33;transition:transform .18s}
.toggle-switch input:checked+.toggle-track{background:var(--purple)}
.toggle-switch input:checked+.toggle-track::after{transform:translateX(18px)}
[dir="rtl"] .toggle-switch input:checked+.toggle-track::after{transform:translateX(-18px)}
.toggle-switch input:focus-visible+.toggle-track{outline:3px solid #9b79ed;outline-offset:3px}
.settings-card .toggle-row+p,.settings-card label.toggle-row~p{margin-top:12px}

/* Celebration / applause */
.celebration{position:relative;height:0}
.confetti{position:absolute;top:-10px;width:9px;height:14px;border-radius:2px;opacity:0;animation:confetti-fall linear forwards}
@keyframes confetti-fall{0%{opacity:1;transform:translate(0,-10px) rotate(0)}100%{opacity:0;transform:translate(calc(var(--dx,0)*120px),210px) rotate(540deg)}}
@media(prefers-reduced-motion:no-preference){.practice-card.cheer .node.solved{animation:cheer-pop .5s ease-out}}
@keyframes cheer-pop{0%{transform:scale(1)}35%{transform:scale(1.22)}70%{transform:scale(.96)}100%{transform:scale(1)}}

/* Countdown shown over the question before auto-advancing */
.countdown{position:absolute;inset:0;z-index:5;display:grid;place-items:center;font-family:Outfit,sans-serif;font-weight:700;font-size:120px;line-height:1;color:var(--purple);background:#ffffffd9;border-radius:18px;pointer-events:none;text-shadow:0 2px 10px #6b43d926}
[dir="rtl"] .countdown{font-family:'Heebo',sans-serif}
@media(prefers-reduced-motion:no-preference){.countdown.tick{animation:countdown-pop .5s ease-out}}
@keyframes countdown-pop{0%{transform:scale(.5);opacity:.2}45%{transform:scale(1.1);opacity:1}100%{transform:scale(1);opacity:1}}
@media(max-width:740px){.countdown{font-size:92px}}

/* Skip-to-next affordance (shown after a wrong attempt) */
.skip-button{display:block;background:none;color:var(--purple);font-size:13px;font-weight:600;margin:0 auto 18px;padding:8px 10px;border-radius:9px}
.skip-button:hover{background:#f0ebfc}
.skip-button span{font-size:16px;vertical-align:middle;margin-left:5px}
[dir="rtl"] .skip-button span{margin-left:0;margin-right:5px;display:inline-block;transform:scaleX(-1)}