:root{--ink:#173c56;--text:#23394a;--muted:#607689;--line:#dce5eb;--blue:#245f87;--soft:#eef4f8;--red:#ad3a34;--red-soft:#fff0ed;--green:#206859;--paper:#fff;--board:#f8f4e9;--board-line:#c5b58f;--shadow:0 8px 32px #173c5609;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;color:var(--text);background:#f4f7f9;font-size:16px;line-height:1.6}*{box-sizing:border-box}body{margin:0}button,a{-webkit-tap-highlight-color:transparent}button{font:inherit;cursor:pointer;touch-action:manipulation}button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid #277daa;outline-offset:3px}button{color:inherit}button:disabled{cursor:default;opacity:.4}h1,h2,h3,p{margin:0}h2{font-size:1.25rem}h3{font-size:1.05rem}p{line-height:1.75}button{border:0}a{color:var(--blue);text-underline-offset:3px}.topbar{max-width:1040px;margin:auto;padding:22px 24px 18px;display:flex;align-items:center;justify-content:space-between}.brand{display:flex;align-items:center;gap:11px}.brand-seal{display:grid;place-items:center;width:44px;height:44px;border:1px solid var(--ink);border-radius:12px;background:var(--ink);color:#fff;font-family:"STKaiti","KaiTi",serif;font-size:28px}.brand h1{font-size:1.25rem;letter-spacing:.1em;line-height:1.35}.brand div>span,.top-note{font-size:.875rem;color:var(--muted)}main{max-width:1000px;margin:0 auto;padding:0 24px 24px}.main-tabs{display:flex;gap:6px;border-bottom:1px solid var(--line);padding:0 0 10px}.main-tabs button{flex:1;min-height:48px;background:transparent;border-radius:10px;color:var(--muted);font-weight:600}.main-tabs button span{font-size:.75rem;font-weight:500;margin-right:8px;opacity:.75}.main-tabs button[aria-current="page"]{background:var(--ink);color:white}.intro{padding:22px 0 18px;min-height:118px}.intro h2{font-size:1.6rem;font-family:"Songti SC","STSong","SimSun",serif;letter-spacing:.025em}.intro p{color:var(--muted);margin-top:6px}.intro b{color:var(--red)}.workspace{display:grid;grid-template-columns:minmax(0,1.08fr) minmax(0,1fr);gap:24px;align-items:start}.board-panel{padding:16px 20px 18px;background:var(--paper);border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow)}.board-top{display:flex;justify-content:space-between;gap:10px;align-items:center;font-size:.875rem;font-weight:600}.text-button{min-height:36px;padding:4px 8px;background:transparent;color:var(--blue);font-size:.875rem;border-radius:6px}.text-button:hover{background:var(--soft)}.board-wrap{margin:10px -1px 0;padding:7px;background:var(--board);border-radius:12px;border:1px solid #e4dac2}.board{position:relative;aspect-ratio:9/10;width:100%;isolation:isolate;user-select:none;-webkit-user-select:none}.board svg{position:absolute;inset:0;width:100%;height:100%;pointer-events:none}.square{position:absolute;width:11.1112%;height:10%;display:grid;place-items:center;background:transparent;padding:0;border-radius:50%;z-index:2}.stone{width:85%;aspect-ratio:1;border:1.5px solid currentColor;border-radius:50%;display:flex;align-items:center;justify-content:center;background:#fffcf3;font-family:"STKaiti","KaiTi","Kaiti SC","Noto Serif CJK SC",serif;font-size:clamp(22px,5.8vw,31px);font-weight:600;line-height:1;color:#292d34;box-shadow:0 2px 1px #9b865538,inset 0 0 0 3px #fffcf3,inset 0 0 0 4px #c5b58f70;position:relative}.stone.red{color:var(--red)}.stone.black{color:#292d34}.square.selected .stone{background:#fff9de;outline:2px solid var(--blue);outline-offset:2px;box-shadow:0 2px 1px #9b865538,inset 0 0 0 3px #fff9de,inset 0 0 0 4px #c5b58f70}.square.legal:empty:after{content:"";width:24%;aspect-ratio:1;border-radius:50%;background:var(--blue);opacity:.75}.square.capture:after{content:"";position:absolute;inset:1%;border:2px dashed var(--blue);border-radius:50%}.square.last:before{content:"";position:absolute;inset:5%;border:2px solid #9b8150;border-radius:9px;transform:rotate(6deg)}.square.blocked:before{content:"";position:absolute;inset:0;border:2px dashed var(--red);border-radius:8px;background:#ad3a3412}.square.target:empty:before{content:"";position:absolute;inset:18%;border:2px dashed var(--red);border-radius:50%;background:#ad3a340b}.square.target:empty:after{content:"＋";color:var(--red);font-size:20px;background:transparent;width:auto;opacity:1}.square.king-danger .stone{background:#ffe4dd;box-shadow:0 0 0 3px #b5343420}.legend{display:flex;align-items:center;gap:17px;color:var(--muted);font-size:.8125rem;margin:12px 0}.legend span{display:flex;align-items:center;gap:6px}.legend span:last-child{margin-left:auto}.dot{width:8px;height:8px;background:var(--blue);border-radius:50%}.ring{width:13px;height:13px;border:1.5px dashed var(--blue);border-radius:50%}.feedback{border-radius:10px;background:var(--soft);padding:12px 14px;min-height:76px;font-size:.9375rem;line-height:1.65;border-left:3px solid var(--blue)}.feedback strong{display:block;color:var(--ink);margin-bottom:2px}.feedback.error{background:var(--red-soft);border-color:var(--red)}.feedback.error strong{color:var(--red)}.feedback.success{background:#edf7f3;border-color:var(--green)}.feedback.success strong{color:var(--green)}.board-actions{display:flex;gap:10px;margin-top:12px}.primary,.secondary{border-radius:10px;padding:10px 16px;min-height:44px;font-weight:600;flex:1}.primary{background:var(--ink);color:white}.secondary{background:var(--soft);color:var(--ink)}.lesson-panel{min-width:0}.step-list{display:flex;flex-direction:column;gap:10px}.step{display:flex;align-items:flex-start;gap:12px;text-align:left;background:white;border:1px solid var(--line);border-radius:13px;padding:15px;width:100%}.step.active{border-color:var(--blue);background:#eef5fa}.step-no{width:28px;height:28px;display:grid;place-items:center;border-radius:50%;background:var(--soft);font-size:.875rem;flex-shrink:0;color:var(--blue);font-weight:700}.active .step-no{background:var(--ink);color:#fff}.step b{display:block;margin-bottom:3px}.step small{font-size:.875rem;line-height:1.6;color:var(--muted);display:block}.note{padding:16px 0;border-bottom:1px solid var(--line);margin-bottom:6px}.note h3{margin-bottom:6px}.note p{color:var(--muted);font-size:.9375rem}.pill-row{display:flex;gap:7px;flex-wrap:wrap;margin:12px 0}.pill{background:white;border:1px solid var(--line);border-radius:20px;padding:6px 13px;min-height:38px;font-size:.875rem}.pill.active{background:var(--ink);border-color:var(--ink);color:white}.piece-picker{display:grid;grid-template-columns:repeat(7,1fr);gap:5px;margin-bottom:16px}.piece-choice{border:1px solid var(--line);background:white;border-radius:10px;padding:9px 0;font-family:"STKaiti","KaiTi",serif;font-size:1.4rem;color:var(--red);min-height:50px}.piece-choice.black{color:#292d34}.piece-choice.black.active{background:#292d34;color:white;border-color:#292d34}.piece-choice.active{background:var(--red);color:white;border-color:var(--red)}.piece-title{display:flex;align-items:center;justify-content:space-between;gap:8px}.piece-title h3{font-size:1.35rem}.side-switch{display:flex;gap:4px;background:#e7eef3;padding:3px;border-radius:8px}.side-switch button{font-size:.875rem;padding:4px 9px;border-radius:6px;background:transparent}.side-switch .active{background:white;box-shadow:0 1px 3px #173c5612}.mnemonic{font-size:1.125rem;color:var(--red);margin:10px 0 6px;font-weight:600}.rule-copy{color:var(--muted)}.tiny-heading{font-size:.8125rem;letter-spacing:.06em;color:var(--muted);margin-top:20px}.tip{background:#eaf1f6;border-radius:12px;padding:15px 16px;margin-top:16px;font-size:.9375rem}.tip b{color:var(--ink);display:block;margin-bottom:4px}.tip p{color:var(--muted)}.progress-track{height:5px;background:#dce5eb;border-radius:5px;overflow:hidden;margin:15px 0 18px}.progress-track span{display:block;background:var(--blue);height:100%;transition:width .25s}.challenge-count{display:flex;justify-content:space-between;align-items:center;color:var(--muted);font-size:.875rem}.quiz-index{display:flex;gap:8px;margin-top:20px;flex-wrap:wrap}.quiz-index button{width:40px;height:40px;border-radius:50%;border:1px solid var(--line);background:white}.quiz-index .active{background:var(--ink);color:white;border-color:var(--ink)}.quiz-index 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p{margin-top:8px}.piece-mobile{display:none}.sr-only{position:absolute;width:1px;height:1px;padding:0;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}.completion{font-size:1.4rem}
@media(min-width:700px){.board-panel{position:sticky;top:18px}.lesson-panel{padding-top:4px}}
@media(max-width:699px){.topbar{padding:17px 18px 15px}.top-note{font-size:.8125rem}.brand-seal{width:39px;height:39px;font-size:25px}.brand h1{font-size:1.125rem}.brand div>span{font-size:.75rem}main{padding:0 14px 24px}.main-tabs{gap:4px}.main-tabs button{font-size:.9375rem;min-height:45px}.main-tabs button span{margin-right:5px;font-size:.75rem}.intro{padding:17px 3px 14px;min-height:0}.intro h2{font-size:1.4rem}.intro p{font-size:.9375rem}.workspace{display:flex;flex-direction:column;gap:16px}.board-panel{padding:10px 12px 12px;border-radius:14px;width:100%}.board-top{min-height:30px}.board-wrap{margin-top:6px;padding:5px}.legend{margin:9px 0;gap:13px}.feedback{padding:10px 12px;min-height:72px}.lesson-panel{width:100%;padding:0 3px}.step-list{gap:8px}.step{padding:12px}.note{padding:10px 0}.quick-rules{margin-top:22px}.rule-grid{grid-template-columns:repeat(2,1fr);gap:16px}.piece-mobile{display:grid;grid-template-columns:repeat(7,1fr);gap:5px;margin-top:12px}.piece-mobile button{padding:4px 0;min-height:40px;font-size:1.25rem}.lesson-panel .piece-picker{display:none}.intro .pill-row{margin:10px 0 0}.piece-title h3{font-size:1.2rem}footer{flex-direction:column;gap:10px}.board-actions{margin-top:10px}.stone{font-size:clamp(20px,6.8vw,31px)}}
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