:root{--bg: #f3f7ff;--card: #ffffff;--ink: #243b53;--muted: #627d98;--primary: #3066be;--primary-dark: #1f4a8f;--good: #2f9e44;--bad: #e03131;--accent: #f59f00;--wood: #8a5a2b;--wood-dark: #6b441f;--shadow: 0 4px 0 rgba(0, 0, 0, .08), 0 6px 18px rgba(31, 74, 143, .12)}*{box-sizing:border-box}html,body,#root{margin:0;padding:0;min-height:100%}body{background:var(--bg);color:var(--ink);font-family:"Baloo 2",Comic Sans MS,Segoe UI,system-ui,sans-serif;font-size:18px;line-height:1.4}h1,h2,h3{margin:0 0 .3em}.screen{max-width:880px;margin:0 auto;padding:18px 18px 60px}.screen-header{display:flex;align-items:center;gap:12px;margin-bottom:8px}.screen-header h2{flex:1;text-align:center;color:var(--primary-dark)}.screen-intro{text-align:center;color:var(--muted);margin:4px 0 18px}button{font-family:inherit;cursor:pointer}.btn-primary,.btn-secondary,.btn-back{border:none;border-radius:14px;padding:12px 20px;font-size:1rem;font-weight:700;transition:transform .08s ease,filter .15s ease}.btn-primary{background:var(--primary);color:#fff;box-shadow:0 4px 0 var(--primary-dark)}.btn-secondary{background:#fff;color:var(--primary-dark);border:2px solid var(--primary)}.btn-back{background:#fff;color:var(--muted);border:2px solid #d9e2ec;padding:8px 14px}.btn-primary:active,.btn-secondary:active,.btn-back:active{transform:translateY(2px)}.btn-primary:disabled,.btn-secondary:disabled{opacity:.45;cursor:not-allowed}.scale{display:flex;flex-direction:column;align-items:center;-webkit-user-select:none;user-select:none}.scale-beam-area{position:relative;width:17em;display:flex;justify-content:center;align-items:flex-start;gap:1em;padding-top:1em;min-height:7.5em}.scale-beam{position:absolute;top:1.2em;left:50%;width:0;height:0;transform-origin:center;transition:transform .5s 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#00000014}.scale-pan-dish.interactive{cursor:pointer;border-color:var(--primary);border-style:dashed}.scale-pan-dish.highlighted{background:linear-gradient(#fff3bf,#ffe08a);border-color:var(--accent);box-shadow:0 0 0 4px #f59f0066}.scale-pan-shapes{display:flex;flex-wrap:wrap;gap:2px;align-items:center;justify-content:center}.scale-pan-hint{font-size:.7em;color:var(--muted);font-style:italic}.scale-pan-shape-btn{background:none;border:none;padding:0;line-height:0}.scale-stand{position:absolute;top:1.2em;left:50%;transform:translate(-50%);display:flex;flex-direction:column;align-items:center;z-index:1}.scale-post{width:.7em;height:5.5em;background:linear-gradient(90deg,var(--wood-dark),var(--wood),var(--wood-dark));border-radius:.3em}.scale-base{width:9em;height:.9em;background:var(--wood-dark);border-radius:.5em;margin-top:-.2em}.scale-status{margin-top:10px;font-weight:800;padding:6px 16px;border-radius:12px}.scale-status.balanced{color:var(--good);background:#e6fcf0}.scale-status.tipped{color:var(--muted);background:#eef2f7}.shape-icon{position:relative;display:inline-flex;align-items:center;justify-content:center}.shape-weight{position:absolute;right:-2px;bottom:-2px;background:#fff;border:2px solid var(--ink);border-radius:50%;width:1.4em;height:1.4em;font-size:.7em;font-weight:800;display:flex;align-items:center;justify-content:center}.home-header{text-align:center;padding:10px 0 18px}.home-header h1{font-size:2.4rem;color:var(--primary-dark)}.tagline{color:var(--muted);margin:0 0 10px}.progress-summary{display:inline-block;background:#fff;padding:8px 18px;border-radius:14px;box-shadow:var(--shadow)}.home-section{background:var(--card);border-radius:20px;padding:18px;margin-bottom:18px;box-shadow:var(--shadow)}.home-section h3{color:var(--primary-dark)}.home-section>p{color:var(--muted);margin-top:0}.big-card{width:100%;background:linear-gradient(135deg,#e7f0ff,#d3e3ff);border:3px solid var(--primary);border-radius:18px;padding:16px;display:flex;flex-direction:column;align-items:center;gap:8px}.big-card-label{font-weight:800;color:var(--primary-dark);font-size:1.1rem}.puzzle-row{display:flex;flex-wrap:wrap;gap:14px}.puzzle-card{flex:1 1 180px;background:#f8fbff;border:2px solid #d9e2ec;border-radius:16px;padding:14px 10px 10px;display:flex;flex-direction:column;align-items:center;gap:6px;position:relative;transition:transform .08s ease,border-color .15s ease}.puzzle-card:hover{border-color:var(--primary)}.puzzle-card:active{transform:translateY(2px)}.puzzle-card-num{position:absolute;top:8px;left:8px;background:var(--primary);color:#fff;width:1.8em;height:1.8em;border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:800}.puzzle-card-stars{font-size:.85rem;color:var(--muted);font-weight:700}.solved-badge{font-size:1.2rem}.given-rules{display:flex;flex-wrap:wrap;gap:18px;justify-content:center;background:#fff7e6;border:2px dashed var(--accent);border-radius:18px;padding:16px;margin-bottom:16px}.given-rule{display:flex;flex-direction:column;align-items:center;gap:4px}.rule-label{font-weight:800;color:#b07700}.puzzle-question{text-align:center;font-size:1.2rem;font-weight:800;color:var(--primary-dark)}.options-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;margin:8px 0 16px}.option-card{background:#fff;border:3px solid #d9e2ec;border-radius:18px;padding:14px 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ease}.option-card:hover:not(:disabled){border-color:var(--primary)}.option-card:active:not(:disabled){transform:translateY(2px)}.option-letter{position:absolute;top:8px;left:10px;font-weight:800;color:var(--muted);font-size:1.1rem}.option-card.correct{border-color:var(--good);background:#ebfbee}.option-card.wrong{border-color:var(--bad);background:#fff0f0}.option-card.reveal{border-color:var(--good);border-style:dashed}.feedback{text-align:center;font-weight:800;font-size:1.1rem;padding:10px;border-radius:14px;margin-bottom:14px}.feedback.good{color:var(--good);background:#ebfbee}.feedback.bad{color:var(--bad);background:#fff0f0}.puzzle-actions{display:flex;justify-content:center;gap:14px}.peek-toggle{display:flex;align-items:center;gap:6px;font-size:.9rem;font-weight:700;color:var(--muted);white-space:nowrap}.sandbox-controls{display:flex;align-items:center;justify-content:center;gap:14px;margin:18px 0;flex-wrap:wrap}.sandbox-hint{color:var(--muted);font-size:.9rem}.shape-tray{background:var(--card);border-radius:18px;padding:14px;box-shadow:var(--shadow)}.shape-tray-label{text-align:center;color:var(--muted);font-weight:700;margin-bottom:10px}.shape-tray-items{display:flex;flex-wrap:wrap;justify-content:center;gap:12px}.tray-shape{background:#f8fbff;border:3px solid #d9e2ec;border-radius:16px;padding:10px 16px;display:flex;flex-direction:column;align-items:center;gap:4px;transition:transform .08s ease,border-color .15s ease}.tray-shape:active{transform:translateY(2px)}.tray-shape.selected{border-color:var(--accent);background:#fff7e6;box-shadow:0 0 0 3px #f59f004d}.tray-shape-name{font-size:.8rem;font-weight:700;color:var(--muted)}.btn-link{background:none;border:none;color:var(--primary);font-weight:700;text-decoration:underline;font-size:.9rem}.weight-controls{background:var(--card);border:2px dashed var(--primary);border-radius:18px;padding:14px;margin:0 0 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0;-moz-appearance:textfield}.stepper-value::-webkit-outer-spin-button,.stepper-value::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}.explain-overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#243b538c;display:flex;align-items:center;justify-content:center;padding:18px;z-index:50}.explain-panel{background:#fff;border-radius:22px;padding:20px;max-width:440px;width:100%;box-shadow:0 14px 40px #0000004d;animation:pop .2s ease}@keyframes pop{0%{transform:scale(.9);opacity:0}to{transform:scale(1);opacity:1}}.explain-header{display:flex;align-items:center;justify-content:space-between}.explain-title{font-weight:800;font-size:1.2rem;color:var(--primary-dark)}.explain-close{background:#eef2f7;border:none;border-radius:50%;width:2em;height:2em;font-weight:800;color:var(--muted)}.explain-step-count{color:var(--muted);font-size:.85rem;margin:4px 0 12px}.explain-body{background:#f8fbff;border-radius:16px;padding:16px;min-height:9em;display:flex;flex-direction:column;align-items:center;gap:10px}.explain-body.is-fact{background:#fff7e6}.explain-fact-tag{align-self:flex-start;background:var(--accent);color:#fff;font-weight:800;font-size:.75rem;padding:3px 10px;border-radius:10px}.explain-caption{text-align:center;font-weight:600;margin:0}.explain-nav{display:flex;justify-content:space-between;margin-top:16px}@media (max-width: 520px){body{font-size:16px}.options-grid{grid-template-columns:1fr}}