:root{--bg:#0b1120;--surface:#131b2e;--surface2:#1a2338;--surface3:#222d48;--text:#e9e8f0;--text2:#94a3b8;--accent:#0959C8;--accent2:#3b82f6;--border:#2a3a55;--success:#22c55e;--error:#ef4444;--shadow:0 4px 24px rgba(0,0,0,.4);--radius:12px;--radius-sm:8px;--font:'Inter',sans-serif}[data-theme="light"]{--bg:#f0f2f6;--surface:#ffffff;--surface2:#f8f9fb;--surface3:#eef0f4;--text:#0f172a;--text2:#475569;--accent:#0959C8;--accent2:#2563eb;--border:#cbd5e1;--shadow:0 4px 24px rgba(0,0,0,.08)}*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}html{font-size:16px}body{font-family:var(--font);background:var(--bg);color:var(--text);min-height:100vh;display:flex;align-items:center;justify-content:center;padding:16px;-webkit-font-smoothing:antialiased;transition:background .3s,color .3s}#app{width:100%;max-width:1100px;background:var(--surface);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow);position:relative;transition:background .3s}.skeleton{position:fixed;inset:0;z-index:9999;background:var(--bg);display:flex;align-items:center;justify-content:center}.skeleton-shimmer{position:absolute;inset:0;background:linear-gradient(90deg,transparent,rgba(255,255,255,.03),transparent);animation:shimmer 1.5s infinite}.skeleton-content{width:100%;max-width:1100px;padding:24px}.skeleton-title{height:28px;width:280px;background:var(--surface2);border-radius:6px;margin-bottom:20px;animation:pulse 1.5s infinite}.skeleton-svg{height:380px;background:var(--surface2);border-radius:12px;margin-bottom:20px;animation:pulse 1.5s infinite}.skeleton-panel{height:120px;background:var(--surface2);border-radius:8px;animation:pulse 1.5s infinite}@keyframes shimmer{0%{transform:translateX(-100%)}100%{transform:translateX(100%)}}@keyframes pulse{0%,100%{opacity:.4}50%{opacity:.8}}.error-boundary{position:fixed;inset:0;z-index:9999;display:flex;align-items:center;justify-content:center;background:var(--bg)}.error-box{background:var(--surface);border-radius:var(--radius);box-shadow:var(--shadow);padding:40px;text-align:center;max-width:420px}.error-icon{font-size:48px;margin-bottom:16px}.error-box h2{margin-bottom:12px;font-size:1.3rem}.error-box p{margin-bottom:20px;color:var(--text2)}.diagram-header{display:flex;justify-content:space-between;align-items:flex-start;margin-bottom:20px;flex-wrap:wrap;gap:12px}.header-left{flex:1}.diagram-title{font-size:1.5rem;font-weight:700;letter-spacing:-.02em;margin-bottom:4px}.diagram-subtitle{font-size:.9rem;color:var(--text2)}.header-right{display:flex;gap:8px;align-items:center}.icon-btn{width:44px;height:44px;border-radius:var(--radius-sm);border:1px solid var(--border);background:var(--surface2);color:var(--text);cursor:pointer;display:flex;align-items:center;justify-content:center;transition:all .2s;min-width:44px;min-height:44px}.icon-btn:hover{background:var(--surface3);border-color:var(--accent)}.icon-btn:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.diagram-container{background:var(--surface2);border-radius:var(--radius);border:1px solid var(--border);overflow:hidden;position:relative;min-height:400px;margin-bottom:16px;transition:background .3s}.diagram-container svg{display:block;width:100%;height:auto}.info-panel{background:var(--surface2);border:1px solid var(--accent);border-radius:var(--radius);padding:20px;margin-bottom:16px;position:relative;animation:slideDown .3s ease;transition:background .3s}@keyframes slideDown{from{opacity:0;transform:translateY(-10px)}to{opacity:1;transform:translateY(0)}}.info-close{position:absolute;top:12px;right:12px;width:36px;height:36px;border:none;background:var(--surface3);color:var(--text);border-radius:50%;cursor:pointer;font-size:16px;display:flex;align-items:center;justify-content:center;min-width:36px;min-height:36px}.info-close:hover{background:var(--accent)}.info-close:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.info-panel h3{font-size:1.15rem;margin-bottom:8px;color:var(--accent2)}.info-panel h4{font-size:.95rem;margin-top:12px;margin-bottom:4px;color:var(--text)}.info-panel p{font-size:.85rem;color:var(--text2);line-height:1.5;margin-bottom:6px}.info-tags{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:10px}.info-tag{background:var(--surface3);color:var(--accent2);padding:3px 10px;border-radius:20px;font-size:.75rem;font-weight:500;border:1px solid var(--border)}.controls-bar{display:flex;align-items:center;gap:16px;flex-wrap:wrap;margin-bottom:16px;padding:12px 16px;background:var(--surface2);border-radius:var(--radius-sm);border:1px solid var(--border);transition:background .3s}.speed-label{display:flex;align-items:center;gap:10px;font-size:.85rem;color:var(--text2);flex:1;min-width:160px}.speed-label input[type="range"]{flex:1;accent-color:var(--accent);height:6px;cursor:pointer}.speed-label input[type="range"]:focus-visible{outline:2px solid var(--accent);outline-offset:2px}#speed-val{min-width:32px;font-weight:600;color:var(--text);font-size:.85rem}.btn-primary{min-width:44px;min-height:48px;padding:8px 24px;border:none;background:var(--accent);color:#fff;border-radius:var(--radius-sm);font-size:.9rem;font-weight:600;cursor:pointer;transition:all .2s;font-family:var(--font);display:inline-flex;align-items:center;justify-content:center;gap:6px}.btn-primary:hover{background:var(--accent2)}.btn-primary:focus-visible{outline:2px solid var(--accent2);outline-offset:2px}.btn-primary:active{transform:scale(.97)}.challenge-section{background:var(--surface2);border:1px solid var(--border);border-radius:var(--radius);padding:24px;margin-bottom:16px;transition:background .3s}.challenge-section h2{font-size:1.2rem;margin-bottom:16px;color:var(--text)}.question-block{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-sm);padding:16px;margin-bottom:12px;transition:background .3s}.question-block h3{font-size:.95rem;margin-bottom:10px;color:var(--text);line-height:1.4}.q-option{display:flex;align-items:flex-start;gap:10px;padding:8px 10px;margin:4px 0;border-radius:6px;cursor:pointer;transition:background .15s;min-height:44px}.q-option:hover{background:var(--surface3)}.q-option input[type="radio"]{margin-top:3px;accent-color:var(--accent);min-width:18px;min-height:18px}.q-option input[type="radio"]:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.q-option label{font-size:.85rem;color:var(--text2);cursor:pointer;line-height:1.4;flex:1}.q-option.correct{background:rgba(34,197,94,.12);border:1px solid var(--success)}.q-option.correct label{color:var(--success)}.q-option.wrong{background:rgba(239,68,68,.12);border:1px solid var(--error)}.q-option.wrong label{color:var(--error)}.q-feedback{font-size:.8rem;margin-top:6px;padding:8px 10px;border-radius:6px;line-height:1.4}.q-feedback.correct{background:rgba(34,197,94,.08);color:var(--success)}.q-feedback.wrong{background:rgba(239,68,68,.08);color:var(--error)}.challenge-actions{margin-top:16px;display:flex;gap:10px;flex-wrap:wrap}.challenge-result{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-sm);padding:16px;margin-top:16px;text-align:center;transition:background .3s}.challenge-result h3{font-size:1.1rem;margin-bottom:4px}.challenge-result p{font-size:.9rem;color:var(--text2)}.completion-overlay{position:fixed;inset:0;z-index:9998;background:rgba(0,0,0,.7);display:flex;align-items:center;justify-content:center;padding:24px;backdrop-filter:blur(4px)}.completion-card{background:var(--surface);border-radius:var(--radius);box-shadow:var(--shadow);padding:40px;text-align:center;max-width:400px;width:100%}.completion-icon{font-size:56px;margin-bottom:16px}.completion-card h2{font-size:1.5rem;margin-bottom:8px;color:var(--text)}.completion-card p{font-size:.95rem;color:var(--text2);margin-bottom:8px}.completion-card .btn-primary{margin-top:16px}.node-clickable{cursor:pointer;transition:opacity .2s}.node-clickable:hover{opacity:.8}.node-clickable:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.node-active .node-bg{filter:drop-shadow(0 0 12px rgba(9,89,200,.5))}.node-active .node-label{font-weight:700}.flow-dot{fill:var(--accent2);opacity:.8;filter:drop-shadow(0 0 4px rgba(59,130,246,.5))}.pulse-ring{fill:none;stroke:var(--accent2);stroke-width:2;opacity:.5}@media(prefers-reduced-motion:reduce){.skeleton-shimmer{animation:none}.skeleton-title,.skeleton-svg,.skeleton-panel{animation:none}.info-panel{animation:none}.completion-card,.node-clickable,.btn-primary{transition:none}.flow-dot,.pulse-ring{animation:none!important;display:none!important}}@media(max-width:768px){body{padding:8px}#app{padding:16px;border-radius:8px}.diagram-title{font-size:1.2rem}.diagram-container{min-height:320px}.controls-bar{padding:10px 12px;gap:10px}.speed-label{min-width:120px;font-size:.8rem}.challenge-section{padding:16px}.question-block{padding:12px}.completion-card{padding:28px}.info-panel{padding:14px}}@media(max-width:480px){body{padding:4px}#app{padding:10px;border-radius:6px}.diagram-title{font-size:1.05rem}.diagram-subtitle{font-size:.8rem}.diagram-container{min-height:260px;border-radius:6px}.controls-bar{flex-direction:column;align-items:stretch;gap:8px}.speed-label{min-width:100%}.btn-primary{width:100%}.challenge-section{padding:12px;border-radius:6px}.question-block{padding:10px}.info-panel{padding:10px;border-radius:6px}.completion-card{padding:20px;margin:12px}.icon-btn{width:40px;height:40px;min-width:40px;min-height:40px}}