:root{--bg:#f4f2ed;--ink:#171814;--muted:#787a72;--line:#d9d8d0;--board:#c7a873;--board-dark:#80633b;--red:#a5422d;--green:#809b8c;--cell:25px;font-family:Arial,'Hiragino Kaku Gothic ProN',sans-serif}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink)}button{font:inherit;cursor:pointer}.site-header{height:72px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 34px;position:sticky;top:0;background:rgba(244,242,237,.95);z-index:3}.brand{display:flex;align-items:center;gap:11px;color:inherit;text-decoration:none}.brand-mark{display:grid;place-items:center;width:34px;height:34px;border:1px solid var(--ink);font-family:serif;font-size:19px}.brand strong{display:block;font:17px/1.1 serif;font-weight:500}.brand 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