:root{color-scheme:light;--ink:#192032;--muted:#6f7889;--blue:#356bdc;--red:#d15a48;--border:#e4e8ef;--paper:#f6f8fb;font-family:-apple-system,BlinkMacSystemFont,"Hiragino Kaku Gothic ProN","Noto Sans JP",sans-serif;color:var(--ink);background:var(--paper)}*{box-sizing:border-box}body{margin:0}button,a,summary{-webkit-tap-highlight-color:transparent}button{font:inherit;cursor:pointer}button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid #356bdc;outline-offset:5px}main{max-width:1000px;margin:auto;padding:0 40px}header{display:flex;align-items:center;justify-content:space-between;min-height:100px;border-bottom:1px solid var(--border);gap:20px}.brand{display:flex;align-items:center;gap:13px;color:var(--ink);text-decoration:none;font-size:12px;font-weight:700;letter-spacing:1.5px}.brand-mark{font-size:26px;color:var(--blue)}.brand-divider{height:15px;width:1px;background:#ccd2dd}.edition{font-size:12px;letter-spacing:1px;color:var(--muted)}.heading{display:flex;justify-content:space-between;align-items:center;gap:24px;padding:38px 0 30px}.eyebrow{font-size:13px;color:var(--muted);margin:0 0 10px;letter-spacing:2px}h1{font-size:clamp(26px,4vw,36px);letter-spacing:2px;margin:0 0 12px;line-height:1.4}.subtitle{font-size:16px;margin:0;color:#515b6c}.order{display:flex;align-items:center;gap:14px;font-size:14px;white-space:nowrap}.segmented{display:flex;background:#e9edf3;border-radius:10px;padding:4px}.segmented button{border:0;background:transparent;color:var(--muted);padding:10px 20px;border-radius:7px;font-size:14px}.segmented button[aria-pressed=true]{background:white;color:var(--ink);box-shadow:0 2px 5px #19203212}.game-card{background:white;border:1px solid var(--border);border-radius:20px;box-shadow:0 8px 40px #20305604;overflow:hidden}.board-top{display:flex;align-items:center;justify-content:center;gap:38px;padding:22px 30px;border-bottom:1px solid #edf0f5}.player{display:flex;align-items:center;gap:13px;font-size:15px}.player small{display:block;font-size:12px;color:var(--muted);margin-top:3px}.color-line{width:26px;height:4px;border-radius:3px;background:var(--blue)}.cpu .color-line{background:var(--red)}.score{font-size:22px;font-variant-numeric:tabular-nums;margin-left:12px}.versus{font-size:12px;color:#929aaa;letter-spacing:2px}.status-wrap{text-align:center;padding:24px 16px 0;min-height:85px}#status{font-size:18px;font-weight:650;margin:0 0 7px;line-height:1.6}#status[data-turn=human]{color:var(--blue)}#status[data-turn=cpu]{color:var(--red)}#hint{font-size:14px;color:var(--muted);margin:0;min-height:22px}.board-area{max-width:610px;margin:0 auto;padding:0 18px;background-image:radial-gradient(#d9dfe94d 1px,transparent 1px);background-size:20px 20px;background-position:center}svg{display:block;width:100%;height:auto;overflow:visible}.edge{stroke:#dce2eb;stroke-width:2.2;stroke-linecap:round;pointer-events:none;transition:stroke .15s,stroke-width .15s}.edge.human{stroke:var(--blue);stroke-width:4.5}.edge.cpu{stroke:var(--red);stroke-width:4.5;stroke-dasharray:10 5}.edge.preview{stroke:#7c9fe9;stroke-width:5}.edge.losing{stroke-width:9;filter:drop-shadow(0 0 6px #d15a4860)}.edge.human.losing{filter:drop-shadow(0 0 6px #356bdc60)}.edge-hit{stroke:transparent;stroke-width:22;cursor:pointer;fill:none;pointer-events:stroke}.edge-hit:focus{outline:none}.edge-hit:focus-visible{stroke:#356bdc30}.node{cursor:pointer}.node circle{fill:white;stroke:#c5cddd;stroke-width:2;transition:fill .15s}.node text{fill:var(--ink);font-size:17px;font-weight:600;pointer-events:none;text-anchor:middle;dominant-baseline:central}.node.selected circle{stroke:var(--blue);stroke-width:3;fill:#eaf0fe}.node:focus-visible{outline:none}.node:focus-visible circle{stroke:var(--blue);stroke-width:4}.board-bottom{display:flex;justify-content:space-between;align-items:center;border-top:1px solid #edf0f5;margin:0 26px;padding:18px 0;font-size:13px;color:var(--muted);gap:15px}#move-count{font-size:18px;color:var(--ink);font-variant-numeric:tabular-nums;white-space:nowrap}#move-count span{font-size:12px;color:var(--muted);margin-left:5px}.actions{display:flex;justify-content:center;gap:12px;margin:25px 0}.actions button{min-height:48px;padding:12px 25px;border-radius:10px;font-size:14px;transition:background .15s}.actions span{font-size:19px;margin-right:6px}.primary{background:var(--ink);color:white;border:1px solid var(--ink)}.primary:hover{background:#303e58}.secondary{background:white;color:#475165;border:1px solid #d9dfe9}.secondary:hover{background:#edf1f8}.guide{max-width:680px;margin:0 auto 30px;font-size:14px;color:var(--muted)}summary{cursor:pointer;padding:14px 2px;list-style:none;display:flex;justify-content:space-between;border-bottom:1px solid var(--border)}summary::-webkit-details-marker{display:none}.guide-content{font-size:14px;line-height:1.9}.guide a{color:var(--blue)}footer{border-top:1px solid var(--border);display:flex;justify-content:space-between;gap:16px;color:#87909f;font-size:12px;padding:22px 0 28px;letter-spacing:1px}@media(max-width:650px){main{padding:0 20px}header{min-height:70px}.edition{display:none}.brand{font-size:10px;letter-spacing:1px}.heading{align-items:flex-start;flex-direction:column;padding:27px 0 23px;gap:20px}.order{align-self:flex-end}.segmented button{padding:8px 23px}.game-card{border-radius:14px}.board-top{gap:18px;padding:18px 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