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80px;display:flex;position:relative;overflow:auto}.input-checkpoint-title{color:#555;text-align:center;margin-top:40px;margin-bottom:6px;padding-bottom:8px;font-size:1.8rem;font-weight:800}.input-checkpoint-title span{color:#843fa1}.input-checkpoint-subtitle{color:#666;margin-top:8px;margin-bottom:24px;font-size:1.1rem}.input-checkpoint-expr{background:#f5f5f7;border:2px solid #ddd;border-radius:12px;justify-content:center;align-self:center;align-items:center;margin-bottom:20px;padding:20px 32px;display:flex}.input-checkpoint-expr math-field{font-size:1.5rem}.input-checkpoint-answer-row{justify-content:center;align-items:center;gap:14px;margin-top:8px;display:flex}.input-checkpoint-answer-label{color:#555;white-space:nowrap;font-size:1rem;font-weight:600}.instruction-screen{box-sizing:border-box;background:#fff;flex-direction:column;height:100%;display:flex;overflow:hidden}.instruction-columns{scroll-behavior:smooth;flex:1;grid-template-columns:1fr 1fr;min-height:0;padding:8px 16px 8px 22px;display:grid;overflow-y:auto}.instruction-left{border-right:1px solid #e8e8e8;flex-direction:column;gap:14px;padding-right:16px;display:flex}.instruction-right{flex-direction:column;align-items:center;gap:14px;padding-left:18px;display:flex}.instruction-example-title-row{color:#843fa1;text-transform:uppercase;letter-spacing:.07em;padding-top:4px;font-size:1rem;font-weight:800}.instruction-step-row{flex-direction:column;gap:4px;animation:.3s ease-out both stepReveal;display:flex}.instruction-step-lbl{color:#843fa1;text-transform:uppercase;letter-spacing:.06em;font-size:1rem;font-weight:800}.instruction-step-caption{color:#444;font-size:1rem;line-height:1.5}.instruction-step-math{justify-content:center;align-items:center;width:100%;min-height:56px;padding-top:4px;animation:.3s ease-out 50ms both stepReveal;display:flex}.instruction-step-math math-field{font-size:1.5rem}.instruction-dots-row{flex-shrink:0;align-items:center;gap:6px;padding:2px 22px 4px;display:flex}.instruction-dot{background:#ccc;border-radius:50%;flex-shrink:0;width:7px;height:7px;transition:background .25s,transform .25s}.instruction-dot.active{background:#843fa1;transform:scale(1.3)}.instruction-dot.done{background:#4caf50}.instruction-audio-status{color:#bbb;flex-shrink:0;align-items:center;gap:6px;padding:2px 22px 0;font-size:.7rem;display:flex}.audio-playing-dot{background:#843fa1;border-radius:50%;flex-shrink:0;width:6px;height:6px;animation:.9s ease-in-out infinite audioPulse}.instruction-nav{border-top:1px solid #e8e8e8;flex-shrink:0;justify-content:space-between;align-items:center;gap:10px;padding:8px 20px 12px;display:flex}.instruction-next-btn{color:#fff;cursor:pointer;white-space:nowrap;background:#843fa1;border:none;border-radius:6px;padding:7px 20px;font-size:.83rem;font-weight:700;transition:background .2s}.instruction-next-btn:hover{background:#9b5fc0}.instruction-prev-btn{color:#888;cursor:pointer;white-space:nowrap;background:0 0;border:1px solid #ccc;border-radius:6px;padding:7px 16px;font-size:.83rem;font-weight:600;transition:all .2s}.instruction-prev-btn:hover:not(:disabled){color:#843fa1;border-color:#843fa1}.instruction-prev-btn:disabled{opacity:.25;cursor:not-allowed}.instruction-skip-btn{color:#888;cursor:pointer;white-space:nowrap;background:0 0;border:1px solid #ccc;border-radius:6px;padding:6px 12px;font-size:.76rem;transition:all .2s}.instruction-skip-btn:hover{color:#843fa1;border-color:#843fa1}.instruction-mode-toggle{border:1px solid #ccc;border-radius:6px;display:flex;overflow:hidden}.mode-btn{color:#888;cursor:pointer;background:0 0;border:none;padding:5px 11px;font-size:.73rem;font-weight:600;transition:all .2s}.mode-btn.active{color:#fff;background:#843fa1}@keyframes stepReveal{0%{opacity:0;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}@keyframes popIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.lesson-scale-root{transform-origin:top;transform:scale(var(--lesson-scale,1));margin-bottom:calc((var(--lesson-scale,1) - 1) * 598px)}