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768px){.page{padding:25px;border-radius:20px}.main-title{font-size:2.5rem}.page-title{font-size:1.8rem}.activity-cards{flex-direction:column;align-items:center}.venn-container{width:300px;height:220px}.venn-container.three-venn{width:350px;height:280px}.calc-step{font-size:1.5rem}.answer-input{flex-direction:column;align-items:center}.answer-input input{width:100%}.progress-bar{bottom:15px;padding:10px 20px}.topic-cards{flex-direction:column}.segment-demo{flex-direction:column;align-items:center}.segment-arrow{transform:rotate(90deg)}}.back-btn{position:absolute;top:20px;left:20px;background:#fffc;border:2px solid var(--primary);color:var(--primary);padding:8px 16px;font-size:.9rem;border-radius:20px;cursor:pointer;font-weight:700;transition:all .3s ease;font-family:inherit;z-index:10}.back-btn:hover{background:var(--primary);color:#fff}.topic-cards{display:flex;justify-content:center;gap:30px;margin:40px 0;flex-wrap:wrap}.topic-card{background:#fff;padding:30px 35px;border-radius:24px;cursor:pointer;transition:all .3s ease;box-shadow:0 8px 30px #0000001f;border:3px solid transparent;text-align:center;min-width:280px}.topic-card:hover{transform:translateY(-8px);border-color:var(--primary);box-shadow:0 16px 40px #6366f140}.topic-icon{font-size:3.5rem;margin-bottom:15px}.topic-card h3{font-size:1.5rem;color:var(--primary);margin-bottom:10px}.topic-card p{font-size:1rem;color:var(--text-light);margin-bottom:15px}.topic-tag{display:inline-block;background:linear-gradient(135deg,#e0e7ff,#c7d2fe);color:var(--primary);padding:6px 16px;border-radius:20px;font-size:.85rem;font-weight:700}.grid-container{display:flex;justify-content:center;align-items:center;margin:25px 0;width:100%;min-height:300px}.grid-svg{display:block;width:min(100%,560px);max-width:100%;height:auto;flex-shrink:0}.cell-appear{animation:cellFadeIn .5s ease-out}@keyframes cellFadeIn{0%{opacity:0;transform:scale(.8)}to{opacity:1;transform:scale(1)}}.interactive-cell{transition:all .3s ease}.interactive-cell:hover{fill:#f0f9ff!important;stroke:#60a5fa!important;stroke-width:2!important;transform:scale(1.05);filter:drop-shadow(0 4px 6px rgba(0,0,0,.1))}.number-text{animation:numberPulse 1s ease-in-out infinite}@keyframes numberPulse{0%,to{transform:scale(1)}50%{transform:scale(1.1)}}@keyframes celebrate{0%{transform:scale(1)}50%{transform:scale(1.2)}to{transform:scale(1)}}.celebrate{animation:celebrate .6s ease-in-out}.star-burst{position:absolute;width:100px;height:100px;pointer-events:none;z-index:1000}@keyframes correctAnimation{0%{transform:scale(1)}50%{transform:scale(1.1);box-shadow:0 0 20px #10b981}to{transform:scale(1)}}.result-box.correct{animation:correctAnimation .5s ease-in-out}.concept-box{background:linear-gradient(135deg,#dbeafe,#bfdbfe);padding:25px;border-radius:20px;margin:25px 0;border:3px solid #3b82f6;text-align:center}.concept-box p{font-size:1.2rem;color:#1e40af;margin-bottom:15px}.concept-list{display:flex;justify-content:center;gap:20px;flex-wrap:wrap}.concept-item{background:#fff;padding:12px 20px;border-radius:15px;font-size:1.1rem;font-weight:700;color:#1e40af;box-shadow:0 4px 12px #0000001a}.segment-demo{display:flex;justify-content:center;align-items:center;gap:20px;margin:30px 0;flex-wrap:wrap}.segment-box{background:#fff;padding:20px;border-radius:20px;box-shadow:0 8px 25px #0000001a;border:3px solid var(--primary)}.segment-box h4{font-size:1.1rem;color:var(--primary);margin-bottom:15px;text-align:center}.segment-result{text-align:center;font-size:1rem;color:var(--text-dark);margin-top:10px}.segment-arrow{font-size:2.5rem;color:var(--primary);font-weight:700}.problem-nav{display:flex;justify-content:space-between;margin:30px 0;gap:20px}.nav-btn{background:linear-gradient(135deg,var(--primary) 0%,#8b5cf6 100%);color:#fff;border:none;padding:12px 25px;font-size:1rem;border-radius:25px;cursor:pointer;font-weight:700;transition:all .3s ease;font-family:inherit;flex:1}.nav-btn:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 8px 25px #6366f166}.nav-btn:disabled{background:#d1d5db;cursor:not-allowed;transform:none;box-shadow:none}.celebration-overlay{position:fixed;top:0;left:0;width:100%;height:100%;pointer-events:none;z-index:1000}.celebration-stars{position:absolute;top:0;left:0;width:100%;height:100%}.celebration-stars .star{animation:celebration-star 1s ease-out forwards}@keyframes celebration-star{0%{opacity:0;transform:scale(0) rotate(0)}50%{opacity:1;transform:scale(1.2) rotate(180deg)}to{opacity:0;transform:scale(1) rotate(360deg)}}.celebration-text{position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);text-align:center;z-index:1001}.celebration-emoji{font-size:4rem;animation:celebration-emoji 1s ease-in-out}.celebration-message{font-size:3rem;font-weight:700;color:var(--primary);margin-top:10px;animation:celebration-message 1s ease-in-out;text-shadow:2px 2px 0 rgba(0,0,0,.1)}@keyframes celebration-emoji{0%{opacity:0;transform:scale(0) rotate(-10deg)}50%{opacity:1;transform:scale(1.2) rotate(10deg)}to{opacity:1;transform:scale(1) rotate(0)}}@keyframes celebration-message{0%{opacity:0;transform:translateY(20px)}50%{opacity:1;transform:translateY(-10px)}to{opacity:1;transform:translateY(0)}}