*{box-sizing:border-box}.bridges-wrap{color:#111827;background:#fff;max-width:760px;margin:0 auto;padding:32px 24px 64px;font-family:Segoe UI,Roboto,sans-serif}.bridges-header{flex-wrap:wrap;align-items:baseline;gap:16px;margin-bottom:24px;display:flex}.back-link{color:#4c1d95;white-space:nowrap;font-size:.9rem;font-weight:600;text-decoration:none}.back-link:hover{text-decoration:underline}.bridges-title{background:linear-gradient(135deg,#5b21b6,#7c3aed,#4338ca);-webkit-text-fill-color:transparent;letter-spacing:-.5px;-webkit-background-clip:text;background-clip:text;font-size:2rem;font-weight:900}.story{color:#374151;flex-direction:column;gap:14px;margin-bottom:32px;font-size:1.05rem;line-height:1.7;display:flex}.story strong,.story em{color:#4c1d95}.story-cta{color:#4c1d95;background:#fff;border:1px solid #e5e7eb;border-left:4px solid #a855f7;border-radius:0 10px 10px 0;padding:12px 16px;font-weight:600}.map-container{flex-direction:column;align-items:center;gap:16px;margin-bottom:32px;display:flex}.map-svg{background:#fff;border:1px solid #e5e7eb;border-radius:20px;width:100%;max-width:420px;height:auto;box-shadow:0 2px 12px #0000000f}.bridge-path{fill:none;stroke:#d1d5db;stroke-width:7px;stroke-linecap:round;cursor:pointer;transition:stroke .15s,stroke-width .15s}.bridge-hit{cursor:pointer}.bridge-available{stroke:#a855f7;stroke-width:8px}.bridge-available:hover{stroke:#7c3aed;stroke-width:10px}.bridge-crossed{stroke:#e5e7eb;stroke-width:6px;opacity:.6}.label-circle{fill:#fff;stroke:#a855f7;stroke-width:2.5px}.label-circle-done{fill:#a855f7;stroke:#7c3aed;stroke-width:2px}.label-text{fill:#5b21b6;pointer-events:none;-webkit-user-select:none;user-select:none;font-size:11px;font-weight:700}.label-circle-done~.label-text{fill:#fff}.bridge-label-g:hover .label-circle{fill:#faf5ff}.node{fill:#7c3aed;stroke:#fff;stroke-width:3px;filter:drop-shadow(0 2px 4px #7c3aed33)}.node-active{fill:#f59e0b;stroke:#fff;stroke-width:3px;filter:drop-shadow(0 0 8px #f59e0b80)}.node-label{fill:#6b7280;font-size:11px;font-weight:700}.node-id{fill:#fff;pointer-events:none;-webkit-user-select:none;user-select:none;font-size:16px;font-weight:900}.you-are-here{pointer-events:none;font-size:18px}.shake{animation:.55s cubic-bezier(.36,.07,.19,.97) shake}@keyframes shake{10%,90%{transform:translate(-2px)}20%,80%{transform:translate(4px)}30%,50%,70%{transform:translate(-6px)}40%,60%{transform:translate(6px)}}.map-msg{color:#4c1d95;text-align:center;opacity:0;min-height:1.8rem;font-size:1.05rem;font-weight:600;transition:opacity .2s}.map-msg-visible{opacity:1}.walk-path{color:#4b5563;text-align:center;background:#fff;border:1px solid #e5e7eb;border-radius:12px;width:100%;max-width:420px;padding:8px 16px;font-size:.95rem;line-height:1.6}.walk-label{color:#4c1d95;font-weight:700}.walk-node{color:#4c1d95;font-weight:800}.walk-arrow{color:#9ca3af}.walk-stuck{color:#ef4444;font-weight:700}.map-actions{flex-wrap:wrap;justify-content:center;gap:12px;display:flex}.btn-reset-map{color:#4c1d95;cursor:pointer;background:#fff;border:2px solid #e5e7eb;border-radius:12px;padding:10px 24px;font-size:.95rem;font-weight:700;transition:border-color .12s,background .12s}.btn-reset-map:hover{background:#faf5ff;border-color:#c4b5fd}.btn-explain{color:#fff;cursor:pointer;background:linear-gradient(135deg,#5b21b6,#7c3aed);border:none;border-radius:12px;padding:10px 24px;font-size:.95rem;font-weight:700;transition:transform .12s,box-shadow .12s;box-shadow:0 3px 10px #7c3aed33}.btn-explain:hover{transform:scale(1.03);box-shadow:0 5px 16px #7c3aed4d}.hint-bar{text-align:center;color:#9ca3af;font-size:.9rem;font-style:italic}.euler-reveal{color:#374151;background:#fff;border:1px solid #e5e7eb;border-radius:20px;flex-direction:column;gap:14px;padding:28px 28px 32px;font-size:1.05rem;line-height:1.7;display:flex}.euler-reveal h2{color:#4c1d95;margin-bottom:4px;font-size:1.6rem;font-weight:900}.euler-reveal strong{color:#4c1d95}.euler-reveal em{color:#4c1d95;font-style:italic}.degree-table{background:#fafafa;border:1px solid #e5e7eb;border-radius:14px;flex-direction:column;gap:8px;padding:16px;display:flex}.degree-row{grid-template-columns:28px 1fr auto auto;align-items:center;gap:10px;font-size:.95rem;display:grid}.degree-node{color:#fff;background:#7c3aed;border-radius:50%;justify-content:center;align-items:center;width:28px;height:28px;font-size:1.1rem;font-weight:900;display:flex}.degree-name{color:#4b5563;font-weight:600}.degree-bridges{color:#9ca3af;letter-spacing:2px}.degree-count{color:#4b5563;white-space:nowrap;font-weight:700}.degree-odd{color:#dc2626}.euler-conclusion{color:#7f1d1d;background:#fff;border:1px solid #fca5a5;border-left:4px solid #ef4444;border-radius:0 10px 10px 0;padding:12px 16px;font-size:1.05rem}.euler-sign{color:#4c1d95;text-align:right;font-style:italic;font-weight:600}