:root{font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;color:#233d36;background:#f5f6f0;font-synthesis:none}*{box-sizing:border-box}body{margin:0}button,a{-webkit-tap-highlight-color:transparent}button{font:inherit;border:1px solid #d7e2d8;border-radius:12px;padding:11px 17px;background:#fff;color:#28695d;cursor:pointer}button:hover{background:#edf4ec}button:focus-visible,a:focus-visible{outline:3px solid #d7ad60;outline-offset:3px}[hidden]{display:none!important}header{display:flex;align-items:center;gap:28px;padding:22px 4vw;border-bottom:1px solid #dde4d9;background:#fffdfa}.brand{text-decoration:none;color:#234f44;font-size:25px;font-weight:650;white-space:nowrap}.brand span{display:block;font-size:12px;font-weight:400;color:#849184;margin-top:4px;letter-spacing:3px}.pair-code{display:flex;align-items:center;gap:16px;margin-left:auto}.pair-code span{font-size:13px;color:#718276}.pair-code strong{font-size:28px;letter-spacing:5px;font-variant-numeric:tabular-nums}.tools{display:flex;gap:10px}main{max-width:1500px;padding:30px 5vw;margin:auto}.lesson-meta{display:flex;align-items:center;gap:20px;color:#839080;font-size:15px;margin:0 4px 20px}.lesson-meta span:first-child{font-weight:600;color:#315c4d;font-size:19px}.lesson-meta span:last-child{margin-left:auto;font-variant-numeric:tabular-nums}.board{min-height:60vh;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center;background:#fffefa;border:1px solid #e2e7dc;border-radius:30px;padding:50px 5vw;box-shadow:0 16px 70px #254d3610;position:relative;overflow:hidden}.accent{width:48px;height:5px;background:#c5a15e;border-radius:10px;margin-bottom:40px}.cue{font-size:clamp(48px,7vw,112px);font-weight:550;line-height:1.5;overflow-wrap:anywhere;max-width:100%;color:#275e4f;white-space:pre-wrap}.cue.pinyin{font-family:Arial,"PingFang SC",sans-serif;font-weight:500;letter-spacing:2px}.instruction{font-size:22px;color:#82937d;margin:26px 0 12px}h1{font-size:clamp(30px,4vw,56px);font-weight:550;margin:12px 0 25px}#emptyHint{max-width:650px;font-size:20px;line-height:1.9;color:#839080}.stage{font-size:17px;color:#a1854a;min-height:26px;margin-top:22px}footer{margin-top:28px;text-align:center;color:#859380;font-size:14px;line-height:2}footer span{display:block;font-size:12px}.notice{background:#fff0d2;border-radius:12px;padding:14px;text-align:center;color:#705620}dialog{max-width:460px;width:90%;border:1px solid #dbe5d8;border-radius:24px;padding:28px;color:#254739}dialog::backdrop{background:#173b3159;backdrop-filter:blur(3px)}dialog h2{font-size:23px}dialog p{line-height:1.7;color:#768875}dialog>div{display:flex;justify-content:flex-end;gap:12px;margin-top:24px}.primary{background:#28695d;color:#fff}.primary:hover{background:#1f564b}@media(max-width:760px){header{flex-wrap:wrap;gap:18px;padding:18px}.brand{font-size:22px}.pair-code{gap:10px}.pair-code strong{font-size:24px;letter-spacing:3px}.tools{width:100%;justify-content:flex-end}.tools button{font-size:13px;padding:9px 12px}main{padding:24px 18px}.lesson-meta{flex-wrap:wrap;font-size:12px;gap:10px}.board{min-height:58vh;padding:35px 18px;border-radius:22px}.accent{margin-bottom:25px}.cue{font-size:48px}.instruction,#emptyHint{font-size:17px}.stage{font-size:14px}}:fullscreen header{padding-top:18px}:fullscreen .board{min-height:69vh}