/* ===== 分章站基础（对齐 /fde/） ===== */
li.part>span{display:block;color:var(--sidebar-active);font-weight:700;font-size:.74rem;
  letter-spacing:.12em;padding:.5rem .7rem 0;border-top:1px solid #423c32;font-family:var(--sans);}
.side-head .backlinks{margin-top:.9rem;display:grid;grid-template-columns:1fr 1fr;gap:.45rem;
  font-family:var(--sans);font-size:12px;}
.side-head .backlinks a{text-align:center;padding:.44rem .2rem;border-radius:6px;white-space:nowrap;
  color:var(--sidebar-active);text-decoration:none;border:1px solid rgba(127,216,208,.35);
  background:rgba(127,216,208,.07);transition:.18s;}
.side-head .backlinks a:hover{background:rgba(127,216,208,.18);border-color:var(--sidebar-active);}
.pagehead{max-width:var(--maxw);margin:0 auto;padding:2.6rem 2.2rem 0;}
.pagehead .crumb{font-family:var(--sans);font-size:12.5px;letter-spacing:.06em;color:var(--ink-faint);}
.pagehead .crumb a{color:var(--ink-faint);text-decoration:none;border-bottom:1px dotted var(--line);}
.pagehead .crumb a:hover{color:var(--accent);}
.pager{max-width:var(--maxw);margin:3.4rem auto 0;padding:1.6rem 2.2rem 0;
  border-top:1px solid var(--line);display:flex;align-items:center;gap:10px;
  font-family:var(--sans);font-size:14px;}
.pager a{flex:1;padding:.85rem 1rem;border:1px solid var(--line);border-radius:8px;
  background:var(--paper);color:var(--ink-soft);text-decoration:none;transition:.18s;}
.pager a:hover{border-color:var(--accent);color:var(--accent);background:#fff;}
.pager a.next{text-align:right;}
.pager a.mid{flex:0 0 auto;padding:.85rem 1.1rem;text-align:center;}
.pager a.dis{visibility:hidden;}
.pager-back{max-width:var(--maxw);margin:1.1rem auto 0;padding:0 2.2rem;display:flex;gap:10px;
  font-family:var(--sans);font-size:13.5px;}
.pager-back a{flex:1;text-align:center;padding:.72rem .9rem;border:1px dashed var(--line);
  border-radius:8px;color:var(--ink-soft);text-decoration:none;transition:.18s;}
.pager-back a:hover{border-style:solid;border-color:var(--accent);color:var(--accent);background:#fff;}
.credit{max-width:var(--maxw);margin:1.6rem auto 0;padding:0 2.2rem 4rem;
  font-family:var(--sans);font-size:12.5px;line-height:1.85;color:var(--ink-faint);}
.credit a{color:var(--accent);text-decoration:none;border-bottom:1px solid rgba(29,107,102,.35);}
.tocpage{max-width:var(--maxw);margin:0 auto;padding:0 2.2rem 4rem;}
.tocpage h2{font-size:1.35rem;margin:2.6rem 0 1.2rem;letter-spacing:.04em;}
.toclist{list-style:none;padding:0;margin:0;}
.toclist li{border-bottom:1px solid var(--line-soft);}
.toclist a{display:flex;gap:1rem;align-items:baseline;padding:.95rem .3rem;
  text-decoration:none;color:var(--ink);transition:.16s;}
.toclist a:hover{background:var(--concept);padding-left:.7rem;}
.toclist .num{font-family:var(--sans);font-size:12px;color:var(--accent);
  min-width:2.4rem;letter-spacing:.08em;}
.toclist .tt{flex:1;font-size:1.02rem;}
.toclist .tt small{display:block;font-family:var(--sans);font-size:12.5px;
  color:var(--ink-faint);margin-top:2px;}
.parthead{font-family:var(--sans);font-size:12px;letter-spacing:.14em;
  color:var(--ink-faint);margin:2.2rem 0 .4rem;text-transform:uppercase;}
.sister{max-width:var(--maxw);margin:0 auto;padding:0 2.2rem 2rem;}
.sister .box{display:block;border:1px solid var(--line);border-left:4px solid var(--accent2);
  border-radius:8px;background:var(--paper);padding:1.2rem 1.4rem;text-decoration:none;color:var(--ink);}
.sister .box:hover{border-color:var(--accent);background:var(--concept);}
.sister .k{font-family:var(--sans);font-size:11.5px;letter-spacing:.14em;color:var(--accent2);text-transform:uppercase;}
.sister .t{font-family:var(--sans);font-weight:700;font-size:1.08rem;margin:.35rem 0 .4rem;}
.sister .d{font-size:.92rem;color:var(--ink-soft);line-height:1.75;}

/* ===== Markdown 补充 ===== */
.md > h1:first-child{margin-top:.2rem;}
.md h2{scroll-margin-top:1.2rem;}
.md h3{scroll-margin-top:1.2rem;}
.md hr{border:0;border-top:1px solid var(--line);margin:2.4rem 0;}
.md .tablewrap{overflow-x:auto;margin:1.5rem 0;-webkit-overflow-scrolling:touch;}
.md .tablewrap table{margin:0;min-width:34rem;}
.md ul,.md ol{padding-left:1.5rem;}
.md li{margin:.32rem 0;}
.md li.task{list-style:none;margin-left:-1.15rem;display:flex;gap:.55rem;align-items:baseline;}
.md li.task .box{flex:0 0 auto;width:.82rem;height:.82rem;border:1.5px solid var(--accent);
  border-radius:3px;display:inline-block;position:relative;top:.12rem;}
.md .formula{font-family:Georgia,"Times New Roman",serif;font-size:1.14rem;text-align:center;
  background:var(--concept);border-left:4px solid var(--concept-b);border-radius:8px;
  padding:1.15rem 1rem;margin:1.6rem 0;letter-spacing:.02em;overflow-x:auto;}
.md pre{font-size:.83rem;}
.md details{border:1px solid var(--line);border-radius:8px;background:var(--paper);
  padding:.9rem 1.2rem;margin:1.5rem 0;}
.md summary{cursor:pointer;font-family:var(--sans);font-weight:700;color:var(--accent);font-size:.95rem;}
.md .tag{font-family:var(--sans);font-size:.72em;font-weight:700;letter-spacing:.02em;
  padding:.06em .42em;border-radius:4px;white-space:nowrap;vertical-align:.06em;}
.tag-official{background:#e2f2ec;color:#146b52;}
.tag-paper{background:#e9e6f6;color:#584394;}
.tag-community{background:#e6eef6;color:#2b5b8a;}
.tag-original{background:#f6ead9;color:#96591f;}
.tag-measured{background:#fbe8e5;color:#a23c30;}
.tag-inferred{background:#eeeae2;color:#6b5f4e;}
.tag-unverified{background:#f2e2e2;color:#8a3f3f;}
#cover h1.booktitle .fde{font-size:3.05rem;letter-spacing:-.045em;line-height:.95;}
#cover h1.booktitle .cn{font-size:2.75rem;}
#cover .booksub{font-size:1.35rem;}
@media (max-width:900px){
  .pagehead,.pager,.pager-back,.credit,.tocpage,.sister{padding-left:1.15rem;padding-right:1.15rem;}
  .pager,.pager-back{flex-wrap:wrap;}
  .pager a,.pager-back a{flex:1 1 40%;}
  .side-head .backlinks{grid-template-columns:1fr 1fr;}
}