:root{--ink:#1b3045;--muted:#547087;--blue:#1c6891;--line:#dbe4eb;--bg:#f3f7fa;--paper:white;--teal:#277d70}
*{box-sizing:border-box}body{font-family:"Noto Sans CJK SC","Microsoft YaHei",sans-serif;color:var(--ink);font-size:15px;line-height:1.78;background:var(--bg);margin:0}
main{max-width:1000px;margin:0 auto;padding:22px 18px 60px}.hero{padding:22px 26px;background:#1c4968;color:#fff;border-radius:16px;margin:0 0 19px}
h1{font-size:24px;margin:0 0 6px}h2{font-size:18px;line-height:1.5;margin:0 0 7px}h3{font-size:15px;margin:14px 0 7px}
.muted,.meta{color:var(--muted);font-size:12.5px}.hero .muted{color:#d6e8f3}.card{background:#fff;border:1px solid var(--line);border-radius:13px;padding:18px 21px;margin:14px 0;break-inside:avoid}
.options{display:grid;gap:8px}.opt{display:block;border:1px solid #dfebf1;background:#fbfdfe;padding:8px 12px;border-radius:9px;cursor:pointer}
.opt input{margin-right:8px;accent-color:var(--blue)}.qtext{margin:14px 0}.diagram{width:min(100%,660px);height:auto;max-height:190px;object-fit:contain;display:block;margin:10px auto}
.toolbar{display:flex;gap:10px;flex-wrap:wrap;margin:12px 0}.btn{border:1px solid #b5c9d8;background:#fff;padding:9px 14px;border-radius:9px;cursor:pointer;font-size:14px;color:#163d58}.btn.primary{background:#1c688f;color:#fff;border-color:#1c688f}
.feedback{margin-top:12px;background:#eff8f5;padding:14px 16px;border-radius:11px}.feedback.wrong{background:#fff4f0}.feedback ol{padding-left:22px}.feedback li{margin-bottom:9px}
.inline-note{background:#f5f8fa;padding:10px 13px;margin:8px 0;border-radius:8px}label.guess{display:inline-flex;align-items:center;gap:6px;margin:8px 15px 0 0;color:#4c6173}
.tag{font-size:12px;background:#e7f0f7;color:#1e5679;border-radius:999px;padding:3px 9px}.status{display:inline-block;color:#155f51;font-weight:600}.source{border-left:3px solid #cad9e4;padding-left:10px;margin-top:9px}
pre{white-space:pre-wrap;word-break:break-word;background:#f6f9fb;padding:12px;border-radius:9px}.answer-space{height:29px;border-bottom:1px dashed #ccd9e1;margin-top:12px}
#toast{font-size:13px;color:#155f51}mjx-container{max-width:100%;overflow-x:auto!important;overflow-y:hidden!important}
@media(max-width:600px){main{padding:12px 9px 45px}.card{padding:15px}.hero{padding:17px}h1{font-size:21px}}
@media print{@page{size:A4;margin:13mm 15mm}body{background:#fff;font-size:11pt}main{max-width:unset;padding:0}.hero{color:#1b3045;background:#fff;border-bottom:2px solid #1b3045;border-radius:0;padding:0 0 12px}.hero .muted{color:#456}.card{border:0;border-bottom:1px solid #d6dde3;border-radius:0;padding:9px 0;margin:9px 0;break-inside:avoid-page}.toolbar,.no-print{display:none!important}.diagram{max-height:105px}.opt{border:0;padding:0}.feedback{background:#fff;padding:0}.answer-space{height:18px}}