*{box-sizing:border-box;margin:0;padding:0;font-family:Arial,Helvetica,sans-serif}
body{min-height:100vh;background:#f2f4f8;display:flex;justify-content:center;align-items:center;padding:16px}
.container{width:100%;max-width:720px;background:#fff;padding:24px;border-radius:14px;box-shadow:0 5px 18px rgba(0,0,0,.12)}
h1{text-align:center;color:#1565c0;margin-bottom:16px}
.status{text-align:center;font-size:22px;font-weight:bold;color:#1565c0;margin:12px 0 16px}
.toolbar{display:flex;justify-content:center;align-items:end;gap:10px;flex-wrap:wrap;margin-bottom:18px}
.toolbar label{display:block;font-size:13px;font-weight:bold;margin-bottom:5px}
select,button{padding:10px 13px;border-radius:8px;border:1px solid #ccc;font-size:15px}
button{background:#1565c0;color:#fff;border:0;cursor:pointer}
button:hover{background:#0d47a1}
#board{display:grid;justify-content:center;width:100%;max-width:560px;margin:18px auto;gap:0}
.cell{position:relative;width:var(--cell-size);height:var(--cell-size);min-width:0;min-height:0;padding:0;text-align:center;font-size:clamp(15px,4vw,25px);font-weight:bold;background:#fff;color:#1565c0;border:1px solid #555;border-radius:0;outline:none}
.cell:focus{background:#eef6ff;box-shadow:inset 0 0 0 2px #1565c0;z-index:2}
.cage-label{position:absolute;top:2px;left:4px;font-size:clamp(8px,1.7vw,12px);line-height:1;font-weight:800;color:#222;pointer-events:none;z-index:3}
.cage-top{border-top:3px solid red}.cage-bottom{border-bottom:3px solid red}
.cage-left{border-left:3px solid red}.cage-right{border-right:3px solid red}
.fixed{color:#2b8ea7;background:#f7f9fc}
#message{text-align:center;min-height:32px;margin-top:14px;font-size:18px;font-weight:bold}
.success{color:#2e7d32}.error{color:#c62828}
.game-info{margin-top:18px;padding:15px 18px;background:#eef7ff;border-left:5px solid #1565c0;border-radius:10px}
.game-info h3{color:#1565c0;margin-bottom:8px}.game-info p{margin:6px 0;line-height:1.5}
@media(max-width:600px){
 body{padding:8px;align-items:flex-start}
 .container{padding:13px;border-radius:10px}
 h1{font-size:27px}
 .status{font-size:19px}
 .toolbar{flex-direction:column;align-items:stretch}
 select,button{width:100%}
 #board{margin:15px auto;max-width:100%}
 .game-info{padding:12px 14px;font-size:13px}
}
/* Home navigation */
.home-button{display:inline-flex;align-items:center;justify-content:center;gap:6px;margin:0 auto 16px;padding:9px 16px;border-radius:9px;background:#1769e0;color:#fff;text-decoration:none;font-weight:700;font-size:14px;box-shadow:0 4px 10px rgba(23,105,224,.18);transition:.2s}.home-button:hover{background:#1258bd;transform:translateY(-1px)}