/* ===== 人工智能导论期末题库 · 样式 ===== */

/* --- 四主题变量 --- */
:root{
  --primary:#46589E;
  --primary-d:#36467F;
  --surface:#F5F6FA;
  --s-container:#FFFFFF;
  --p-container:#E5E9F5;
  --card:#FFFFFF;
  --line:#E3E6EF;
  --on-surface:#1B1F2E;
  --on-var:#6A7189;
  --outline:#CED3E3;
  --ok:#1F8A5B; --ok-bg:#E3F6EC;
  --no:#C0392B; --no-bg:#FDECEA;
  --banner1:#46589E; --banner2:#6A7FC6;
  --shadow:0 4px 16px rgba(20,20,45,.06);
}
html[data-theme="blue"]{
  --primary:#3D6FD8;
  --primary-d:#2E56AC;
  --surface:#EEF3FD;
  --s-container:#FFFFFF;
  --p-container:#DDE8FB;
  --card:#FFFFFF;
  --line:#D9E3F7;
  --on-surface:#14203A;
  --on-var:#5A6885;
  --outline:#C2D3F0;
  --banner1:#2F5FCC; --banner2:#5B8AE8;
}
html[data-theme="warm"]{
  --primary:#8A6A3C;
  --primary-d:#6E5230;
  --surface:#F7F1E4;
  --s-container:#FFFBF2;
  --p-container:#EFE2C8;
  --card:#FFFBF2;
  --line:#E6D8BC;
  --on-surface:#2E2618;
  --on-var:#57472E;
  --outline:#D8C6A4;
  --ok:#3F7A45; --ok-bg:#E8F2E3;
  --no:#A8432C; --no-bg:#F8E9E2;
  --banner1:#8A6A3C; --banner2:#B4905A;
  --shadow:0 4px 16px rgba(90,70,40,.08);
}
html[data-theme="dark"]{
  --primary:#8FA3E0;
  --primary-d:#A9B9EC;
  --surface:#14151A;
  --s-container:#1E2029;
  --p-container:#2C3147;
  --card:#1E2029;
  --line:#2B2F3C;
  --on-surface:#E8EAF2;
  --on-var:#9AA1B8;
  --outline:#3A3F52;
  --ok:#5FD39A; --ok-bg:#17342A;
  --no:#FF8B7B; --no-bg:#3A1E1B;
  --banner1:#2E3A63; --banner2:#44548C;
  --shadow:0 4px 16px rgba(0,0,0,.32);
}

*,*::before,*::after{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;background:var(--surface);color:var(--on-surface);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  font-size:15px;line-height:1.7;
  transition:background .18s,color .18s;
}
button{font-family:inherit;color:inherit;cursor:pointer;border:none;background:none}
h1,h2,h3,p{margin:0}
.app{min-height:100vh;display:flex;flex-direction:column}

/* --- 顶栏 --- */
.topbar{
  position:sticky;top:0;z-index:60;display:flex;align-items:center;gap:8px;
  padding:calc(8px + env(safe-area-inset-top)) 12px 8px;
  background:var(--surface);border-bottom:1px solid var(--line);
  max-width:1080px;margin:0 auto;width:100%;
}
.iconbtn{
  width:34px;height:34px;flex:0 0 34px;border-radius:50%;
  display:grid;place-items:center;color:var(--on-var);
  background:var(--s-container);border:1px solid var(--line);
}
.iconbtn:active{transform:scale(.94)}
.userbtn{color:var(--primary);background:var(--p-container);border-color:transparent}
.tbtitle{flex:1;min-width:0;text-align:center}
.tbtitle h1{font-size:15px;font-weight:700;letter-spacing:.2px;line-height:1.3;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.tbtitle p{
  font-size:11.5px;color:var(--on-var);line-height:1.5;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis;margin-top:1px;
}
.tbtitle .sch{color:var(--primary);font-weight:700;margin-right:9px}

/* --- 页面与视图 --- */
main{flex:1;width:100%}
.view{display:none}
.view.on{display:block}
.page{max-width:1080px;margin:0 auto;padding:14px 14px 40px;width:100%}

/* --- 首页 --- */
.searchrow{
  display:flex;align-items:center;gap:9px;background:var(--s-container);
  border:1px solid var(--line);border-radius:14px;padding:11px 14px;color:var(--on-var);
  box-shadow:var(--shadow);margin-bottom:14px;
}
.searchrow svg{flex:0 0 auto;opacity:.7}
.searchrow input{
  flex:1;border:none;outline:none;background:none;color:var(--on-surface);
  font-size:15px;font-family:inherit;min-width:0;
}
.searchrow input::placeholder{color:var(--on-var);opacity:.85}

.banner{
  border-radius:20px;padding:20px 18px;color:#fff;margin-bottom:16px;
  background:linear-gradient(135deg,var(--banner1),var(--banner2));
  box-shadow:0 6px 20px rgba(70,88,158,.22);
}
.banner h2{font-size:20px;font-weight:700;letter-spacing:.4px}
.bsub{font-size:12.5px;opacity:.9;margin-top:3px}
.bstat{font-size:11.5px;opacity:.82;margin-top:9px;
  border-top:1px solid rgba(255,255,255,.22);padding-top:8px}

.entry6{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-bottom:6px}
.ecard{
  background:var(--card);border:1px solid var(--line);border-radius:16px;
  padding:13px 8px 11px;display:flex;flex-direction:column;align-items:center;gap:3px;
  box-shadow:var(--shadow);transition:transform .12s;
}
.ecard:active{transform:scale(.96)}
.ecard i{font-style:normal;font-size:17px;color:var(--primary);
  width:32px;height:32px;border-radius:10px;background:var(--p-container);
  display:grid;place-items:center;margin-bottom:3px}
.ecard b{font-size:13px;font-weight:600}
.ecard span{font-size:10.5px;color:var(--on-var);line-height:1.4}

.sech{
  font-size:13px;font-weight:700;color:var(--on-surface);
  margin:20px 0 10px;display:flex;align-items:center;gap:7px;
}
.sech::before{content:"";width:3px;height:13px;border-radius:2px;background:var(--primary)}
.sech.first{margin-top:4px}

.chlist{display:flex;flex-direction:column;gap:8px}
.chrow{
  display:flex;align-items:center;gap:11px;width:100%;text-align:left;
  background:var(--card);border:1px solid var(--line);border-radius:14px;
  padding:11px 13px;box-shadow:var(--shadow);
}
.chrow:active{transform:scale(.99)}
.chno{
  flex:0 0 22px;height:22px;border-radius:8px;background:var(--p-container);
  color:var(--primary);font-size:11.5px;font-weight:700;display:grid;place-items:center;
}
.chmid{flex:1;min-width:0}
.chmid b{display:block;font-size:13.5px;font-weight:600;line-height:1.4;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.chmid span{font-size:11px;color:var(--on-var)}
.chev{color:var(--outline);flex:0 0 auto}
.chrow.classic .chno{background:#FDF0DC;color:#B4761C}
html[data-theme="dark"] .chrow.classic .chno{background:#3A2E1C;color:#E0AE63}

.ovcard{background:var(--card);border:1px solid var(--line);border-radius:18px;
  padding:15px 14px 13px;box-shadow:var(--shadow);margin-top:10px}
.ovhead{display:flex;align-items:center;justify-content:space-between;margin-bottom:12px}
.ovhead b{font-size:13.5px;font-weight:700}
.mini{font-size:11px;color:var(--on-var);padding:2px 7px;border-radius:7px;}
.mini:active{background:var(--p-container)}
.ovbody{display:flex;align-items:center;gap:16px}
.ring{position:relative;flex:0 0 auto;display:grid;place-items:center}
.ringv{position:absolute;text-align:center;line-height:1.2}
.ringv b{display:block;font-size:14px;font-weight:700;color:var(--primary)}
.ringv span{font-size:9.5px;color:var(--on-var)}
.ovstats{flex:1;display:grid;grid-template-columns:1fr 1fr;gap:8px 10px}
.st{background:var(--s-container);border-radius:10px;padding:6px 9px}
.st b{display:block;font-size:14.5px;font-weight:700;line-height:1.25}
.st span{font-size:10.5px;color:var(--on-var)}
.bars{margin-top:13px;display:flex;flex-direction:column;gap:7px}
.bar{display:flex;align-items:center;gap:9px}
.bar .bl{flex:0 0 42px;font-size:11px;color:var(--on-var)}
.bar .bt{flex:1;height:7px;border-radius:4px;background:var(--p-container);overflow:hidden}
.bar .bf{height:100%;border-radius:4px;background:var(--primary);width:0;transition:width .3s}
.bar .bn{flex:0 0 62px;text-align:right;font-size:10.5px;color:var(--on-var)}

.exmgrid{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.exmgrid.sm .exm{padding:10px 11px}
.exm{
  background:var(--card);border:1px solid var(--line);border-radius:14px;
  padding:12px 13px;text-align:left;box-shadow:var(--shadow);transition:transform .12s;
}
.exm:active{transform:scale(.98)}
.exm b{display:block;font-size:13.5px;font-weight:600}
.exm span{font-size:11px;color:var(--on-var)}
.exm.on{border-color:var(--primary);background:var(--p-container);box-shadow:0 0 0 2px rgba(70,88,158,.16)}
.exm.on b{color:var(--primary-d)}

.examref{background:var(--card);border:1px solid var(--line);border-radius:16px;
  padding:14px;box-shadow:var(--shadow)}
.examtags{display:flex;gap:7px;margin-bottom:11px;flex-wrap:wrap}
.pill{font-size:10.5px;padding:3px 9px;border-radius:20px;
  background:var(--p-container);color:var(--primary);font-weight:600}
.extab{width:100%;border-collapse:collapse;font-size:12px}
.extab th,.extab td{padding:6px 4px;text-align:left;border-bottom:1px solid var(--line)}
.extab th{font-size:10.5px;color:var(--on-var);font-weight:600}
.extab td:first-child{font-weight:600}
.extab tr:last-child td{border-bottom:none}
.exnote{font-size:11.5px;color:var(--on-var);margin-top:10px;line-height:1.65}
.exnote b{color:var(--primary-d)}
.exnote.dim{opacity:.8;margin-top:6px}

.dlrow{display:grid;grid-template-columns:repeat(3,1fr);gap:9px}
.dlbtn{background:var(--card);border:1px solid var(--line);border-radius:12px;
  padding:11px 6px;font-size:12.5px;font-weight:600;box-shadow:var(--shadow)}
.dlbtn:active{transform:scale(.96)}
.wiperow{display:flex}
.wipe{font-size:11.5px;color:var(--on-var);padding:7px 12px;border-radius:10px;
  border:1px dashed var(--outline);width:100%}
.wipe:active{background:var(--p-container)}

.discfoot{margin-top:24px;padding-top:14px;border-top:1px solid var(--line)}
.discfoot p{font-size:10.5px;line-height:1.8;color:var(--on-var);opacity:.85}

/* --- 底部导航 --- */
.bnav{
  position:fixed;left:0;right:0;bottom:0;z-index:50;display:flex;
  background:var(--s-container);border-top:1px solid var(--line);
  padding:6px 0 calc(6px + env(safe-area-inset-bottom));
  max-width:1080px;margin:0 auto;
}
.bnav button{flex:1;display:flex;flex-direction:column;align-items:center;gap:2px;
  color:var(--on-var);font-size:10px;padding:3px 0}
.bnav button.on{color:var(--primary);font-weight:600}
body.plainbot .bnav{display:none}

/* --- 主题球 --- */
.themebar{display:flex;gap:8px;justify-content:center;padding:8px 0 20px}
.themebtn{display:flex;align-items:center;gap:5px;font-size:10.5px;
  color:var(--on-var);padding:5px 9px;border-radius:20px;background:var(--s-container);
  border:1px solid var(--line)}
.themebtn .sw{width:11px;height:11px;border-radius:50%;display:inline-block;
  border:1px solid rgba(0,0,0,.12)}
.themebtn.on{box-shadow:inset 0 0 0 2px var(--primary);color:var(--primary)}

/* --- 开始练习设置 --- */
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip{
  font-size:12.5px;padding:8px 13px;border-radius:11px;
  background:var(--card);border:1px solid var(--line);color:var(--on-surface);
  transition:transform .1s;
}
.chip:active{transform:scale(.96)}
.chip.on{background:var(--primary);border-color:var(--primary);color:#fff;font-weight:600}
.chip .cn{font-size:10.5px;opacity:.72;margin-left:4px}
.footnote{font-size:11px;color:var(--on-var);margin-top:8px;line-height:1.6}
.startrow{margin-top:22px}
.btn2{
  display:inline-flex;align-items:center;justify-content:center;
  font-size:13px;font-weight:600;padding:10px 20px;border-radius:12px;
  background:var(--primary);color:#fff;box-shadow:0 4px 12px rgba(70,88,158,.22);
  min-width:76px;height:38px;
}
.btn2:active{transform:scale(.97)}
.btn2.big{width:100%;height:46px;font-size:15px;border-radius:14px}
.btn2.ghost{background:var(--card);color:var(--primary);border:1px solid var(--outline);
  box-shadow:none;height:34px;font-size:12px;padding:8px 14px;min-width:0}
.btn2[disabled]{opacity:.45;pointer-events:none}

/* --- 练题 --- */
.drillhead{margin-bottom:12px}
.drillsub{font-size:12px;color:var(--on-var);font-weight:600}
.drillhint{font-size:11px;color:var(--on-var);opacity:.8;margin-top:2px}
.sqgrid{display:flex;flex-direction:column;gap:12px}
body.plainbot .view.on{padding-bottom:0}

.qcard{
  background:var(--card);border:1px solid var(--line);border-radius:18px;
  padding:15px 14px 14px;box-shadow:0 4px 16px rgba(20,20,45,.06);position:relative;
}
.qhead{display:flex;align-items:center;gap:7px;margin-bottom:9px;padding-right:52px}
.qno{min-width:22px;height:22px;border-radius:8px;background:var(--p-container);
  color:var(--primary);font-size:11.5px;font-weight:700;display:grid;place-items:center;
  padding:0 5px;flex:0 0 auto}
.qch{font-size:10.5px;color:var(--on-var);flex:1;min-width:0;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.qtype{font-size:10px;color:var(--primary);background:var(--p-container);
  padding:1px 6px;border-radius:6px;flex:0 0 auto;font-weight:600}
.qredo{
  position:absolute;top:13px;right:12px;font-size:11px;color:var(--on-var);
  background:var(--s-container);padding:2px 7px;border-radius:9px;line-height:1.5;
}
.qredo:active{background:var(--p-container)}
.qstem{font-size:15.5px;line-height:1.8;font-weight:600;margin-bottom:11px;
  word-break:break-word}
.qstem p{margin:0 0 6px}
.qstem p:last-child{margin-bottom:0}
.qimg{display:block;max-width:100%;height:auto;border-radius:10px;margin:8px 0 10px;
  border:1px solid var(--line);background:#fff}

/* 选项 */
.opts{display:flex;flex-direction:column;gap:9px}
.aopt{
  display:flex;align-items:flex-start;gap:10px;
  padding:12px 13px;border-radius:14px;background:var(--s-container);
  border:1px solid var(--line);font-size:15px;line-height:1.72;text-align:left;width:100%;
  transition:transform .1s,background .15s,border-color .15s;
}
.aopt .ol{
  flex:0 0 23px;width:23px;height:23px;border-radius:50%;
  display:grid;place-items:center;font-size:12px;font-weight:700;
  background:var(--p-container);color:var(--primary);margin-top:1px;
}
.aopt .ot{flex:1;min-width:0;word-break:break-word}
.aopt .os{font-size:10.5px;font-weight:700;color:var(--primary);flex:0 0 auto;
  align-self:center;opacity:0;transition:opacity .12s}
.aopt.sel{background:var(--p-container);border-color:var(--primary);
  box-shadow:0 0 0 2px rgba(70,88,158,.18)}
.aopt.sel .ol{background:var(--primary);color:#fff}
.aopt.sel .os{opacity:1}
.aopt.hit{background:var(--ok-bg);border-color:var(--ok)}
.aopt.hit .ol{background:var(--ok);color:#fff}
.aopt.hit .ol::after{content:"✓"}
.aopt.hit .ol span{display:none}
.aopt.miss{background:var(--no-bg);border-color:var(--no)}
.aopt.miss .ol{background:var(--no);color:#fff}
.aopt.miss .ol::after{content:"✕"}
.aopt.miss .ol span{display:none}
.aopt.lock{pointer-events:none}
@keyframes pickPop{0%{transform:scale(1)}45%{transform:scale(.975)}100%{transform:scale(1)}}
.aopt.pop{animation:pickPop .22s ease}

/* 判题行 */
.ansline{margin-top:11px;font-size:12.5px;padding:9px 12px;border-radius:11px;
  background:var(--s-container);border-left:3px solid var(--outline);line-height:1.65}
.ansline.right{border-left-color:var(--ok);color:var(--ok);background:var(--ok-bg)}
.ansline.wrong{border-left-color:var(--no);color:var(--no);background:var(--no-bg)}

/* 解析 */
.exwrap{margin-top:10px;font-size:13px;line-height:1.78}
.exwrap[hidden]{display:none}
.exbrief{color:var(--on-var)}
.exbadge{display:inline-block;font-size:9.5px;font-weight:700;padding:1px 6px;
  border-radius:5px;background:var(--p-container);color:var(--primary);margin-right:6px;
  vertical-align:1px}
.extip{font-weight:600;color:var(--on-surface);margin-bottom:7px;font-size:12.5px}
.ex-opt{display:block;padding:7px 0;border-bottom:1px dashed var(--line)}
.ex-opt:last-child{border-bottom:none}
.ex-opt .el{display:inline-block;width:17px;height:17px;border-radius:5px;
  background:var(--p-container);color:var(--primary);font-size:10.5px;font-weight:700;
  text-align:center;line-height:17px;margin-right:6px;vertical-align:1px}
.ex-opt .et{color:var(--on-surface);font-weight:600}
.ex-opt .ew{display:block;color:var(--on-var);font-size:12px;margin-top:3px;
  padding-left:23px}
.ex-opt.good .el{background:var(--ok);color:#fff}
.ex-opt.bad .el{background:var(--no);color:#fff}
.ex-more{margin-top:9px;padding:8px 11px;background:var(--s-container);border-radius:9px;
  font-size:12px;color:var(--on-var);line-height:1.7}
.ex-more b{color:var(--primary-d)}

/* 问答自评 */
.qa-hint{margin-top:10px;font-size:12px;color:var(--on-var);padding:9px 12px;
  border-radius:11px;background:var(--s-container);border:1px dashed var(--outline)}
.qa-btns{display:flex;gap:8px;margin-top:9px;flex-wrap:wrap}
.qa-btn{font-size:11.5px;padding:6px 12px;border-radius:9px;
  background:var(--s-container);border:1px solid var(--line);color:var(--on-var)}
.qa-btn:active{background:var(--p-container)}
.qa-ans{margin-top:10px;font-size:13px;line-height:1.8;color:var(--on-surface);
  padding:11px 13px;border-radius:11px;background:var(--s-container);
  border-left:3px solid var(--primary)}
.qa-ans[hidden]{display:none}
.qa-ans b{color:var(--primary-d)}

/* 底栏：透明浮层，只有一颗按钮 */
.drillfoot{
  display:flex;justify-content:flex-end;position:fixed;left:0;right:0;bottom:0;z-index:55;
  max-width:600px;margin:0 auto;padding:0 16px calc(12px + env(safe-area-inset-bottom));
  background:none;pointer-events:none;
}
.drillfoot .btn2{pointer-events:auto;box-shadow:0 4px 12px rgba(20,20,45,.20);}
#v-drill,#v-exam{padding-bottom:calc(104px + env(safe-area-inset-bottom));}

/* 结算 */
.settled{background:var(--card);border:1px solid var(--line);border-radius:18px;
  padding:16px 15px;box-shadow:var(--shadow);margin-bottom:12px;text-align:center}
.settled .big{font-size:26px;font-weight:700;color:var(--primary);line-height:1.3}
.settled .big small{font-size:13px;color:var(--on-var);font-weight:600}
.settled p{font-size:12px;color:var(--on-var);margin-top:6px}

/* --- 知识学习 --- */
.knowtop{display:flex;align-items:center;gap:16px;background:var(--card);
  border:1px solid var(--line);border-radius:18px;padding:14px;box-shadow:var(--shadow)}
.kring{position:relative;display:grid;place-items:center;flex:0 0 auto}
.kstats{flex:1;display:grid;grid-template-columns:1fr 1fr;gap:6px 12px}
.kstats div{font-size:11px;color:var(--on-var)}
.kstats b{display:block;font-size:15px;font-weight:700;color:var(--on-surface)}
.knowbtns{display:flex;gap:8px;margin:12px 0 4px;flex-wrap:wrap}

.kp{
  background:var(--card);border:1px solid var(--line);border-radius:16px;
  padding:14px;box-shadow:var(--shadow);margin-top:11px;
}
.kp h4{font-size:13.5px;font-weight:700;margin:0 0 8px;
  padding-left:9px;border-left:3px solid var(--primary);line-height:1.4}
.kp p{font-size:13px;line-height:1.8;color:var(--on-surface);margin:0 0 7px}
.kp p:last-child{margin-bottom:0}
.kp .dimb{color:var(--on-var);font-size:12px}
.ktab{width:100%;border-collapse:collapse;font-size:11.5px;margin:8px 0}
.ktab th,.ktab td{border:1px solid var(--line);padding:6px 7px;text-align:left}
.ktab th{background:var(--p-container);color:var(--primary-d);font-weight:600}
.kpill{display:inline-block;font-size:11px;padding:2px 8px;border-radius:7px;
  background:var(--ok-bg);color:var(--ok);margin:2px 4px 2px 0}
.kwarn{background:var(--no-bg);border-left:3px solid var(--no);border-radius:9px;
  padding:8px 11px;font-size:12px;color:var(--on-surface);margin:7px 0}

/* --- 列表（错题/收藏） --- */
.listops{display:flex;gap:9px;margin-bottom:12px;flex-wrap:wrap}
.empty{text-align:center;font-size:12.5px;color:var(--on-var);
  padding:48px 20px;line-height:1.9}

/* --- 试卷 --- */
.examhead{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:12px}
.examtimer{font-size:15px;font-weight:700;color:var(--primary);
  font-variant-numeric:tabular-nums;background:var(--p-container);
  padding:4px 11px;border-radius:10px}
.examtimer.warn{color:var(--no);background:var(--no-bg)}

/* --- 统计 --- */
.statgrid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:14px}
.statbox{background:var(--card);border:1px solid var(--line);border-radius:14px;
  padding:13px;box-shadow:var(--shadow)}
.statbox b{display:block;font-size:22px;font-weight:700;color:var(--primary);line-height:1.3}
.statbox span{font-size:11.5px;color:var(--on-var)}
.spark{display:flex;align-items:flex-end;gap:6px;height:74px;margin-top:8px}
.spark .sp{flex:1;background:var(--p-container);border-radius:5px 5px 0 0;position:relative}
.spark .sp i{position:absolute;bottom:0;left:0;right:0;background:var(--primary);
  border-radius:5px 5px 0 0;display:block}
.sparklab{display:flex;gap:6px;margin-top:4px}
.sparklab span{flex:1;text-align:center;font-size:9px;color:var(--on-var)}

/* --- 搜索 --- */
.srrow{background:var(--card);border:1px solid var(--line);border-radius:13px;
  padding:11px 13px;margin-bottom:8px;box-shadow:var(--shadow);width:100%;text-align:left}
.srrow b{font-size:13px;font-weight:600;display:block;line-height:1.6}
.srrow span{font-size:10.5px;color:var(--on-var)}

/* --- toast / modal --- */
.toast{
  position:fixed;left:50%;bottom:96px;transform:translate(-50%,14px);z-index:200;
  background:rgba(28,30,40,.92);color:#fff;font-size:12.5px;padding:9px 16px;
  border-radius:11px;opacity:0;pointer-events:none;transition:opacity .2s,transform .2s;
  max-width:78vw;text-align:center;line-height:1.6;
}
.toast.on{opacity:1;transform:translate(-50%,0)}
.modal{position:fixed;inset:0;z-index:300;background:rgba(10,12,20,.42);
  display:none;align-items:center;justify-content:center;padding:24px}
.modal.on{display:flex}
.modalbox{background:var(--card);border-radius:18px;padding:20px 18px 16px;
  max-width:360px;width:100%;box-shadow:0 12px 40px rgba(0,0,0,.24)}
.modalbox h3{font-size:14.5px;font-weight:700;margin-bottom:8px}
.modalbox p{font-size:12.5px;color:var(--on-var);line-height:1.75;margin-bottom:14px}
.modalacts{display:flex;gap:9px;justify-content:flex-end}
.modalacts .btn2{height:34px;font-size:12px;padding:8px 16px;min-width:0}
.modalacts .btn2.ghost{background:var(--s-container);color:var(--on-var);
  border:1px solid var(--line);box-shadow:none}

/* --- LaTeX --- */
.tex{font-family:"Cambria Math","Times New Roman",Georgia,serif;font-style:italic;
  font-size:1.02em;letter-spacing:.2px;white-space:nowrap}
.tex u{text-decoration:none}
.tex sup,.tex sub{font-size:.72em;font-style:normal}
.tex .frac{display:inline-flex;flex-direction:column;vertical-align:middle;
  text-align:center;font-size:.9em;line-height:1.15;margin:0 .18em}
.tex .frac>span{display:block;padding:0 .22em}
.tex .frac>span:first-child{border-bottom:1px solid currentColor}
.tex .bigop{font-size:1.25em;font-style:normal}
.texvar{font-style:italic}
.mono{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  font-size:12px;background:var(--s-container);padding:9px 11px;border-radius:9px;
  display:block;white-space:pre-wrap;word-break:break-word;line-height:1.7;
  border:1px solid var(--line);margin:7px 0;overflow-x:auto}

/* --- 字号三档 --- */
html[data-fs="0"] .qstem{font-size:15.5px}
html[data-fs="0"] .aopt{font-size:15px}
html[data-fs="1"] .qstem{font-size:16.5px}
html[data-fs="1"] .aopt{font-size:16px}
html[data-fs="2"] .qstem{font-size:17.5px}
html[data-fs="2"] .aopt{font-size:17px}

/* --- 双栏 --- */
@media (min-width:900px){
  .page{padding:18px 20px 56px}
  .entry6{grid-template-columns:repeat(6,1fr)}
  .sqgrid{display:grid;grid-template-columns:1fr 1fr;column-gap:16px;align-items:start}
  .sqgrid .qcard.wide{grid-column:1/-1}
  .drillfoot{max-width:1080px}
  .bnav{max-width:1080px}
}
@media (max-width:400px){
  .page{padding:12px 11px 36px}
  .entry6{gap:8px}
  .ecard{padding:11px 6px 9px}
  .ecard b{font-size:12px}
  .ecard span{font-size:10px}
  .qstem{font-size:15px}
  .aopt{font-size:14.5px;padding:11px 12px}
  .banner h2{font-size:18px}
}

/* --- 分段函数 cases --- */
.cascase{font-size:1.35em;font-style:normal;line-height:1;vertical-align:-.12em;margin-right:.1em}
.casbody{display:inline-flex;flex-direction:column;vertical-align:middle;
  text-align:left;line-height:1.42;font-size:.96em}
.casbody .casrow{display:grid;grid-template-columns:auto auto;gap:.55em}
.casbody .casl{text-align:left}
.casbody .casr{text-align:left}

/* --- 图片加载失败兜底 --- */
.qimgfail{font-size:11.5px;color:var(--no);background:var(--no-bg);
  border-radius:9px;padding:8px 11px;margin:8px 0;border:1px dashed var(--no)}