:root{
  --bg:#f4f6fb; --card:#fff; --line:#e3e8f0; --primary:#2f6fed; --primary-d:#1f53b8;
  --text:#1f2733; --muted:#73828f; --accent:#fff4e0; --green:#1f9d55;
}
*{box-sizing:border-box}
body{margin:0;font-family:-apple-system,"Microsoft YaHei",Segoe UI,sans-serif;background:var(--bg);color:var(--text);font-size:14px}
.topbar{display:flex;align-items:center;gap:16px;padding:10px 18px;background:linear-gradient(90deg,#2f6fed,#5b8def);color:#fff;box-shadow:0 2px 8px rgba(0,0,0,.08)}
.brand{font-weight:700;font-size:17px}
.brand .sub{font-size:12px;opacity:.8;font-weight:400;margin-left:4px}
.tabs{display:flex;gap:6px;margin-left:10px}
.tab{border:none;background:rgba(255,255,255,.15);color:#fff;padding:6px 16px;border-radius:18px;cursor:pointer;font-size:14px}
.tab.active{background:#fff;color:var(--primary-d);font-weight:700}
.admin-link{margin-left:auto;color:#fff;text-decoration:none;opacity:.9;font-size:13px}
.admin-link:hover{opacity:1}

main{padding:16px}
.panel{display:none}
.panel.active{display:flex;gap:16px;align-items:flex-start}

/* 知识树 */
.tree-wrap{width:300px;flex:0 0 300px;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:10px;max-height:82vh;overflow:auto}
.tree .grade{font-weight:700;margin:8px 0 2px}
.tree .vol{margin:4px 0;padding-left:10px;color:var(--primary-d);font-weight:600}
.tree .chap{cursor:pointer;padding:4px 8px;border-radius:6px;display:flex;gap:6px}
.tree .chap:hover{background:var(--bg)}
.tree .kp{cursor:pointer;padding:3px 8px 3px 22px;color:var(--muted);border-radius:6px}
.tree .kp:hover{background:var(--accent);color:var(--text)}
.tree .kp.active{background:var(--accent);color:var(--primary-d);font-weight:600}

.detail{flex:1;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:20px;min-height:80vh}
.detail .hint{color:var(--muted);text-align:center;margin-top:40px}
.detail h2{margin-top:0}
.detail .meta{color:var(--muted);font-size:13px;margin-bottom:12px}

/* 题库 / 组卷 */
.filters{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:12px}
.filters select,.filters input{padding:6px 10px;border:1px solid var(--line);border-radius:8px;background:#fff;font-size:14px}
.qlist{flex:1;display:flex;flex-direction:column;gap:10px}
.qcard{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:12px 14px}
.qcard .qhead{display:flex;gap:8px;align-items:center;margin-bottom:6px}
.tag{font-size:12px;padding:1px 8px;border-radius:10px;background:var(--bg);color:var(--muted)}
.tag.type{background:#e8f0ff;color:var(--primary-d)}
.tag.diff1{background:#e7f7ee;color:var(--green)}
.tag.diff3{background:#fff4e0;color:#b9760a}
.tag.diff5{background:#fdeaea;color:#c0392b}
.qcard .stem{white-space:pre-wrap;line-height:1.7}
.qcard .qbody{margin-top:8px;border-top:1px dashed var(--line);padding-top:8px;color:#334}
.qcard .qbody b{color:var(--primary-d)}
.chap-line{color:var(--muted);font-size:12px}

/* 组卷 */
#tab-paper{flex-direction:row}
.paper-left{flex:1;display:flex;flex-direction:column;gap:10px}
.auto-row{display:flex;gap:8px;align-items:center;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:10px}
.basket{flex:0 0 280px;width:280px;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:14px;position:sticky;top:16px;max-height:84vh;overflow:auto}
.basket h3{margin:0 0 8px;font-size:15px}
.basket-list{display:flex;flex-direction:column;gap:6px;margin:8px 0}
.basket-item{display:flex;gap:6px;align-items:flex-start;font-size:13px;background:var(--bg);border-radius:8px;padding:6px 8px}
.basket-item .rm{cursor:pointer;color:#c0392b;font-weight:700}
.basket-actions{display:flex;flex-direction:column;gap:8px;margin-top:10px}
button{cursor:pointer;border:none;border-radius:8px;padding:8px 14px;background:var(--primary);color:#fff;font-size:14px}
button:hover{background:var(--primary-d)}
button.ghost{background:#fff;color:var(--primary-d);border:1px solid var(--primary)}