:root{
    --navy:#13294b; --cobalt:#2456c4; --coral:#ff6b4a;
    --paper:#f7f6f2; --ink:#1d2433; --muted:#7a8194;
    --line:#e3e1d9; --card:#ffffff;
    --green:#2f9e5e; --amber:#e8a317; --red:#d64545;
    --shadow:0 1px 2px rgba(19,41,75,.06),0 6px 18px rgba(19,41,75,.07);
    --exercise-font:Arial,"KaiTi","STKaiti","Kaiti SC","DFKai-SB",serif;
  }
  *{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
  html,body{margin:0;height:100%}
  body{font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Segoe UI",sans-serif;
       background:var(--paper);color:var(--ink);font-size:15px;line-height:1.55;
       display:flex;flex-direction:column;height:100%;overflow:hidden}
  button{font-family:inherit;cursor:pointer;border:none;background:none;color:inherit}
  input,textarea{font-family:inherit}
  .hidden{display:none!important}

  /* 习题内容：中文优先使用楷体；英文与拼音（拉丁字母）优先使用 Arial。界面说明保持原字体。 */
  .qb-stem,.interactive-stem,.interactive-options .optbtn,.passageblock h3,.passageblock .passagecontent,
  .paper-sheet,.sectionhead,.modelans,.typed,.mistake-title,.mistake-answer{font-family:var(--exercise-font)}
  .ai-template-note{margin:10px 0 0;padding:10px 12px;border:1px solid #cfe0fa;border-radius:10px;background:#f7faff;color:#40506a;font-size:12px;line-height:1.65}
  .ai-template-note b{color:var(--navy)}
  .manager-head + .ai-template-note{margin:0 0 12px}

  /* 顶栏 */
  header{flex:0 0 auto;display:flex;align-items:center;gap:10px;padding:9px 14px;background:var(--card);
         border-bottom:1px solid var(--line);z-index:30}
  .logo{display:flex;align-items:center;gap:7px;font-weight:800;color:var(--navy);font-size:14px}
  .logo .mon{width:22px;height:18px;border-radius:4px;background:var(--navy);position:relative;flex:0 0 auto}
  .logo .mon::after{content:"";position:absolute;right:2.5px;top:2.5px;width:4px;height:4px;border-radius:50%;background:var(--green)}
  .htitle{font-size:13px;font-weight:600;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;max-width:38vw}
  .spacer{flex:1}
  .roleswitch{display:flex;background:var(--paper);border:1px solid var(--line);border-radius:8px;padding:2px}
  .roleswitch button{padding:5px 9px;border-radius:6px;font-weight:600;font-size:12px;color:var(--muted)}
  .roleswitch button.on{background:var(--card);color:var(--navy);box-shadow:var(--shadow)}

  /* 主体：分屏各自滚动。竖屏=上下，横屏=左右 */
  .scroll{flex:1;display:flex;flex-direction:column;overflow:hidden;min-height:0}

  /* PDF 区 */
  .pdfzone{flex:0 0 62%;background:#eceae3;display:flex;flex-direction:column;position:relative;min-height:0;overflow:hidden}
  .pdfbar{flex:0 0 auto;display:flex;align-items:center;gap:5px;padding:6px 10px;background:var(--card);
          border-bottom:1px solid var(--line);flex-wrap:wrap}
  .pdfbar .seg{font-size:12px;color:var(--muted);margin-left:auto;display:flex;align-items:center;gap:3px}
  .pdfbar .seg button{width:26px;height:26px;border-radius:6px;font-size:16px}
  .pdfbar .seg button:active{background:var(--paper)}
  .pdfscroll{flex:1;overflow:auto;-webkit-overflow-scrolling:touch;display:block;padding:10px;min-height:0;
             touch-action:pan-x pan-y;overscroll-behavior:contain;scrollbar-gutter:stable}
  /* 课堂跟随开启时，学生只能跟随老师视角；老师暂停后才恢复自由滚动。
     overflow:hidden 不影响脚本设置 scrollTop/scrollLeft，因此老师仍能带动学生页面。 */
  .pdfscroll.follow-locked{overflow:hidden!important;touch-action:none!important;overscroll-behavior:none!important}
  .pdfscroll.follow-locked::-webkit-scrollbar{display:none}
  .pdfbar button:disabled{opacity:.35;pointer-events:none}
  .pdfpages{display:flex;flex-direction:column;align-items:center;gap:12px;min-width:100%;width:max-content;
            margin:0 auto;padding-bottom:12px;transform-origin:top center}
  .pdfpage{position:relative;flex:0 0 auto;background:#fff;box-shadow:var(--shadow)}
  .pdfpage canvas{display:block}
  .pdfpage .annoCanvas{position:absolute;left:0;top:0;pointer-events:none;touch-action:none}
  .pdfpages.draw-mode .annoCanvas{pointer-events:auto}
  .pagebadge{position:absolute;right:7px;bottom:7px;z-index:3;padding:2px 7px;border-radius:999px;
             background:rgba(19,41,75,.72);color:#fff;font-size:10px;pointer-events:none}
  .livepill{display:none;align-items:center;gap:5px;padding:3px 8px;border-radius:999px;background:var(--paper);
            border:1px solid var(--line);font-size:10px;font-weight:700;color:var(--muted);white-space:nowrap}
  .livepill.show{display:flex}.livepill.connected{color:var(--green);background:#ecf8f1;border-color:#cfe9da}
  .livepill.connecting{color:var(--amber);background:#fff8e6}.livepill.offline{color:var(--red);background:#fdeeee}
  .livedot{width:7px;height:7px;border-radius:50%;background:currentColor;box-shadow:0 0 0 3px rgba(47,158,94,.12)}
  .zoomseg{display:flex;align-items:center;gap:2px;margin-left:auto;border:1px solid var(--line);border-radius:7px;padding:1px;background:var(--paper)}
  .zoomseg button{height:25px;min-width:27px;padding:0 6px;border-radius:5px;font-size:14px;color:var(--ink)}
  .zoomseg button:active{background:var(--card)}
  .zoomseg #zoomLabel{min-width:48px;font-size:11px;font-weight:700;color:var(--navy)}
  @media (max-width:520px){.pdfbar{gap:4px}.livepill{order:3;margin-left:0}.pdfbar .seg{margin-left:0}.zoomseg{margin-left:auto}}
  .annobtns{display:flex;gap:4px;flex-wrap:wrap}
  .tbtn{width:30px;height:30px;border-radius:7px;display:flex;align-items:center;justify-content:center;color:var(--ink)}
  .tbtn svg{width:17px;height:17px}
  .tbtn.text-tool b{font:800 18px/1 Arial,sans-serif}
  .tbtn:active{background:var(--paper)}
  .tbtn.on{background:var(--navy);color:#fff}
  .tbtn.disabled,.tbtn:disabled{opacity:.35;pointer-events:none}
  .pdfperm{display:flex;align-items:center;gap:7px;margin-top:9px;padding:9px 10px;border-radius:10px;background:var(--paper);border:1px solid var(--line);font-size:12px;color:var(--muted)}
  .pdfperm b{color:var(--navy)}
  .pdfperm .permstate{margin-left:auto;font-weight:700}
  .pdfperm .permstate.on{color:var(--green)}
  .pdfperm .permstate.off{color:var(--red)}
  .switchbtn{padding:7px 10px!important;border-radius:8px!important;font-size:12px!important;font-weight:700!important}
  .switchbtn.allow{background:var(--green)!important;color:#fff!important}
  .switchbtn.revoke{background:var(--red)!important;color:#fff!important}
  .clearstudent{border-color:#efc5c5!important;color:var(--red)!important;background:#fff8f8!important}
  .viewsync{display:flex;align-items:center;gap:7px;flex-wrap:wrap;margin-top:8px;padding:9px 10px;border-radius:10px;background:#eef4ff;border:1px solid #cfe0fa;font-size:12px;color:var(--muted)}
  .viewsync b{color:var(--navy)}
  .viewsync .syncstate{margin-left:auto;font-weight:700;color:var(--green)}
  .viewsync .syncstate.paused{color:var(--amber)}
  .viewsync .syncnow{padding:7px 10px!important;border:1px solid #cfe0fa!important;background:#fff!important;color:var(--cobalt)!important;border-radius:8px!important;font-size:12px!important;font-weight:700!important}
  .viewsync .synctoggle{padding:7px 10px!important;border-radius:8px!important;font-size:12px!important;font-weight:700!important}
  .viewsync .synctoggle.on{background:var(--red)!important;color:#fff!important}
  .viewsync .synctoggle.off{background:var(--green)!important;color:#fff!important}
  .csw{width:18px;height:18px;border-radius:50%;border:2px solid #fff;box-shadow:0 0 0 1px var(--line)}
  .csw.on{box-shadow:0 0 0 2px var(--navy)}

  .pdfempty{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:14px;color:var(--muted);text-align:center;padding:24px}
  .pdfempty .ic{width:48px;height:48px;border-radius:13px;background:var(--card);border:1px dashed var(--line);display:flex;align-items:center;justify-content:center;color:var(--cobalt)}

  /* 答题卡区：独立滚动 */
  .cardzone{flex:1;min-height:0;overflow-y:auto;-webkit-overflow-scrolling:touch;background:var(--paper);padding:14px 14px 100px}

  /* 横屏（电脑/平板）：左右分栏，各自滚动 */
  @media (min-aspect-ratio: 1/1) and (min-width: 820px){
    .scroll{flex-direction:row}
    .pdfzone{flex:0 0 58%;height:100%;border-right:1px solid var(--line)}
    .cardzone{flex:1;height:100%;padding-bottom:100px}
  }
  .cardhead{display:flex;align-items:baseline;gap:8px;margin-bottom:12px}
  .cardhead h2{margin:0;font-size:16px;color:var(--navy)}
  .cardhead .sc{margin-left:auto;font-size:13px;color:var(--muted)}
  .cardhead .sc b{color:var(--navy)}
  .scorebreakdown{display:none;grid-template-columns:repeat(3,minmax(0,1fr));gap:7px;margin:-3px 0 12px}
  .scorebreakdown.show{display:grid}
  .scoreitem{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:8px 9px;min-width:0}
  .scoreitem span{display:block;font-size:10px;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
  .scoreitem b{display:block;margin-top:2px;font-size:14px;color:var(--navy)}
  .scoreitem.teacher b{color:var(--coral)}
  .scoreitem.auto b{color:var(--green)}
  @media(max-width:430px){.scorebreakdown{grid-template-columns:1fr 1fr}.scoreitem.auto{grid-column:1/-1}}

  .q{background:var(--card);border:1px solid var(--line);border-radius:13px;padding:13px;margin-bottom:11px;box-shadow:var(--shadow)}
  .qh{display:flex;align-items:center;gap:8px;margin-bottom:11px}
  .qn{min-width:30px;width:auto;height:30px;padding:0 8px;border-radius:9px;background:var(--navy);color:#fff;font-weight:700;font-size:13px;display:flex;align-items:center;justify-content:center;flex:0 0 auto;white-space:nowrap}
  .sectionhead{margin:18px 2px 9px;padding:9px 12px;border-left:4px solid var(--cobalt);border-radius:0 10px 10px 0;background:#eef4ff;color:var(--navy);font-size:14px;font-weight:800;box-shadow:0 1px 2px rgba(19,41,75,.04)}
  .sectionhead:first-child{margin-top:2px}
  .qt{font-size:11px;font-weight:600;padding:2px 8px;border-radius:6px;background:var(--paper);color:var(--muted)}
  .qp{margin-left:auto;font-size:12px;color:var(--muted)}

  /* 客观题：选项横排圆点 */
  .opts{display:flex;gap:8px;flex-wrap:wrap}
  .optbtn{flex:1;min-width:54px;height:48px;border:1.5px solid var(--line);border-radius:11px;background:var(--card);
          font-size:17px;font-weight:700;color:var(--ink);display:flex;align-items:center;justify-content:center;transition:.12s}
  .optbtn:active{transform:scale(.96)}
  .optbtn.sel{border-color:var(--cobalt);background:#eef4ff;color:var(--cobalt)}
  .optbtn.correct{border-color:var(--green);background:#ecf8f1;color:var(--green)}
  .optbtn.wrong{border-color:var(--red);background:#fdeeee;color:var(--red)}
  .optbtn.locked{pointer-events:none}
  .reschip{margin-top:10px;font-size:13px;font-weight:700;display:inline-flex;align-items:center;gap:5px;padding:4px 10px;border-radius:8px}
  .reschip.ok{background:#e7f6ee;color:var(--green)} .reschip.no{background:#fbe9e9;color:var(--red)}

  /* 简答题 */
  .saqtabs{display:flex;gap:6px;margin-bottom:10px}
  .saqtab{flex:1;padding:7px;border:1px solid var(--line);border-radius:9px;font-size:12px;font-weight:600;color:var(--muted);text-align:center;background:var(--card)}
  .saqtab.on{border-color:var(--cobalt);color:var(--cobalt);background:#eef4ff}
  .saqtab.disabled{opacity:.4;pointer-events:none}

  .canvasbox{border:1px solid var(--line);border-radius:11px;overflow:hidden;background:#fffdf7;position:relative}
  .canvasbox .ctools{display:flex;align-items:center;gap:5px;padding:6px 8px;border-bottom:1px solid var(--line);background:var(--card)}
  .canvasbox .ctools .grow{flex:1}
  .canvasbox .ctools button{font-size:12px;color:var(--muted);padding:4px 8px;border-radius:7px;font-weight:600}
  .canvasbox .ctools button:active{background:var(--paper)}
  .canvasbox canvas{display:block;width:100%;min-height:180px;touch-action:pan-y;background:
    repeating-linear-gradient(to bottom,transparent 0,transparent 35px,rgba(36,86,196,.08) 36px)}
  .canvasbox canvas.draw-mode{touch-action:none;cursor:crosshair}
  .canvasbox canvas.scroll-mode{touch-action:pan-y;cursor:grab}
  .canvasbox .ctools button.mode-on{background:#eef4ff;color:var(--cobalt);box-shadow:inset 0 0 0 1px #cfe0fa}
  .canvasbox .ctools button:disabled{opacity:.38;cursor:not-allowed}
  .canvasgrowhint{padding:6px 9px;border-top:1px dashed var(--line);font-size:10px;color:var(--muted);background:#fff}
  .canvasbox.live-edit{border-color:#aac4f2;box-shadow:0 0 0 2px rgba(36,86,196,.06)}
  .photobox .uploadstate{margin-top:9px;padding:7px 9px;border-radius:8px;background:#eef4ff;color:var(--cobalt);font-size:12px}
  .photobox .thumbs .th a{display:block;width:100%;height:100%}

  .photobox{border:1px dashed var(--line);border-radius:11px;padding:14px;text-align:center;color:var(--muted);background:var(--card)}
  .photobox .thumbs{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px}
  .photobox .thumbs .th{position:relative;width:72px;height:72px;border-radius:9px;overflow:hidden;border:1px solid var(--line)}
  .photobox .thumbs .th img{width:100%;height:100%;object-fit:cover}
  .photobox .thumbs .th.photoerr{display:flex;align-items:center;justify-content:center;background:#fdeeee;padding:5px;text-align:center}
  .photobox .thumbs .th.photoerr a{font-size:10px;color:var(--red);text-decoration:none;line-height:1.25}
  .photobox .thumbs .th button{position:absolute;top:2px;right:2px;width:18px;height:18px;border-radius:50%;background:rgba(0,0,0,.55);color:#fff;font-size:12px;line-height:1}

  textarea.typed{width:100%;border:1px solid var(--line);border-radius:11px;padding:11px;font-size:14px;resize:vertical;min-height:84px;background:#fffdf7}
  textarea.typed:focus{outline:none;border-color:var(--cobalt)}
  textarea.typed:disabled{background:var(--paper);color:var(--ink)}
  .lockhint{font-size:12px;color:var(--muted);text-align:center;padding:14px;background:var(--paper);border-radius:10px}

  /* 评分 */
  .gradebox{margin-top:12px;border-top:1px dashed var(--line);padding-top:11px}
  .modelans{background:#f1faf4;border:1px solid #cfe9da;border-radius:10px;padding:9px 11px;font-size:13px;margin-bottom:10px}
  .modelans .lbl{font-size:11px;font-weight:700;color:var(--green);margin-bottom:3px}
  .grow{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
  .grow .lbl{font-size:12px;color:var(--muted)}
  .si{width:58px;padding:7px;border:1px solid var(--line);border-radius:8px;font-size:14px;text-align:center}
  .si:focus{outline:none;border-color:var(--cobalt)}
  .teach{margin-top:10px;padding:10px;border-radius:10px;background:#fff7f3;border:1px solid #f7d9c9}
  .teach .lbl{font-size:11px;font-weight:700;color:var(--coral);margin-bottom:6px}

  /* 底部固定操作栏 */
  .actionbar{position:fixed;left:0;right:0;bottom:0;background:var(--card);border-top:1px solid var(--line);
             padding:11px 14px calc(11px + env(safe-area-inset-bottom));display:flex;flex-direction:column;gap:7px;z-index:25}
  .btn{padding:12px;border-radius:11px;font-weight:700;font-size:15px;text-align:center}
  .btn.primary{background:var(--cobalt);color:#fff}
  .btn.primary:disabled{opacity:.45}
  .btn.ghost{background:var(--card);border:1px solid var(--line);color:var(--ink);font-size:13px;padding:9px}
  .barhint{font-size:12px;color:var(--muted);text-align:center}
  .barhint.done{color:var(--green);font-weight:600}

  /* 出题面板（底部抽屉） */
  .sheet{position:fixed;inset:0;background:rgba(19,41,75,.4);z-index:50;display:flex;align-items:flex-end}
  .sheet .panel{background:var(--card);border-radius:18px 18px 0 0;width:100%;max-height:90vh;overflow:auto;padding-bottom:20px}
  .sheet .ph{position:sticky;top:0;background:var(--card);padding:15px 16px;border-bottom:1px solid var(--line);display:flex;align-items:center;z-index:2}
  .sheet .ph h3{margin:0;font-size:16px;color:var(--navy)}
  .sheet .pb{padding:15px 16px}
  .linkcard{background:#eef4ff;border:1px solid #cfe0fa;border-radius:11px;padding:12px;margin-bottom:14px}
  .linkcard .lbl{font-size:12px;font-weight:700;color:var(--cobalt);margin-bottom:6px}
  .linkhint{font-size:11px;color:var(--muted);margin:4px 0 9px}
  .pdfpickrow{display:flex;align-items:center;gap:8px;padding:10px;border:1px solid var(--line);border-radius:10px;background:var(--paper);margin-bottom:12px}
  .pdfpickrow .pdfname{flex:1;min-width:0;font-size:12px;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
  .renumberbtn{margin-top:7px;padding:7px 10px;border:1px solid var(--line);border-radius:8px;font-size:12px;font-weight:600;color:var(--cobalt);background:#fff}
  .modebadge{display:inline-flex;align-items:center;padding:2px 7px;border-radius:999px;font-size:10px;font-weight:700;margin-left:6px}
  .modebadge.homework{background:#e7f6ee;color:var(--green)}
  .modebadge.classroom{background:#fff4df;color:#a66b00}
  .linkrow{display:flex;gap:7px}
  .linkrow input{flex:1;padding:8px 10px;border:1px solid var(--line);border-radius:8px;font-size:12px;color:var(--muted);background:#fff}
  .fld{margin-bottom:12px}
  .fld label{display:block;font-size:12px;font-weight:600;color:var(--muted);margin-bottom:5px}
  .fld input,.fld textarea,.fld select{width:100%;padding:9px 11px;border:1px solid var(--line);border-radius:9px;font-size:14px}
  .fld input:focus,.fld textarea:focus,.fld select:focus{outline:none;border-color:var(--cobalt)}
  .draft{border:1px solid var(--line);border-radius:12px;padding:12px;margin-bottom:10px;position:relative}
  .draft .dh{display:flex;align-items:center;gap:8px;margin-bottom:9px}
  .draft .dh .qn{width:26px;height:26px;border-radius:8px;font-size:13px}
  .draft .del{margin-left:auto;color:var(--muted);font-size:18px;width:26px;height:26px;border-radius:7px}
  .draft .del:active{background:var(--paper);color:var(--red)}
  .typesel{display:flex;gap:6px;margin-bottom:10px}
  .typesel button{flex:1;padding:7px;border:1px solid var(--line);border-radius:8px;font-size:12px;font-weight:600;color:var(--muted)}
  .typesel button.on{border-color:var(--cobalt);color:var(--cobalt);background:#eef4ff}
  .corrrow{display:flex;gap:6px;flex-wrap:wrap;margin-top:6px}
  .corrbtn{width:40px;height:40px;border:1.5px solid var(--line);border-radius:9px;font-weight:700;color:var(--ink)}
  .corrbtn.on{border-color:var(--green);background:#ecf8f1;color:var(--green)}
  .toggle{display:flex;align-items:center;gap:8px;font-size:13px;margin-top:8px}
  .toggle input{width:auto;transform:scale(1.2)}
  .addrow{display:flex;gap:8px;margin-top:6px}
  .addrow button{flex:1;padding:11px;border:1px solid var(--line);border-radius:10px;font-weight:600;font-size:13px;color:var(--cobalt)}
  .sheetfoot{position:sticky;bottom:0;background:var(--card);padding:12px 16px;border-top:1px solid var(--line);display:flex;gap:8px}
  .sheetfoot .btn{flex:1}

  /* 学生身份与老师收作业 */
  .identitybox{display:none;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:11px 12px;margin-bottom:12px;box-shadow:var(--shadow)}
  .identitybox.show{display:block}
  .identitybox .idtitle{font-size:12px;font-weight:700;color:var(--navy);margin-bottom:6px}
  .identityrow{display:flex;align-items:center;gap:8px}
  .identityrow input{flex:1;min-width:0;padding:9px 10px;border:1px solid var(--line);border-radius:9px;font-size:14px;background:#fff}
  .identityrow input:focus{outline:none;border-color:var(--cobalt)}
  .identityhint{font-size:11px;color:var(--muted);margin-top:5px}
  .reviewwho{display:flex;align-items:center;gap:9px}
  .reviewavatar{width:34px;height:34px;border-radius:10px;background:#eef4ff;color:var(--cobalt);font-weight:800;display:flex;align-items:center;justify-content:center}
  .reviewwho b{display:block;color:var(--navy)}
  .reviewwho span{font-size:12px;color:var(--muted)}
  .statuspill{margin-left:auto;padding:4px 9px;border-radius:999px;font-size:11px;font-weight:700;white-space:nowrap}
  .statuspill.answering{background:#f2f3f5;color:var(--muted)}
  .statuspill.selfGrading{background:#fff5df;color:#a26b00}
  .statuspill.submitted{background:#eaf2ff;color:var(--cobalt)}
  .statuspill.finalized{background:#e7f6ee;color:var(--green)}

  .receivepanel{max-width:680px;margin:0 auto}
  .receiveheadtools{display:flex;align-items:center;gap:5px}
  .receive-summary{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin-bottom:12px}
  .sumcard{background:var(--paper);border:1px solid var(--line);border-radius:11px;padding:10px;text-align:center}
  .sumcard b{display:block;font-size:20px;color:var(--navy)}
  .sumcard span{font-size:11px;color:var(--muted)}
  .submission-list{display:flex;flex-direction:column;gap:9px}
  .submission-card{border:1px solid var(--line);border-radius:12px;padding:12px;background:#fff;box-shadow:var(--shadow)}
  .submission-top{display:flex;align-items:center;gap:9px}
  .submission-avatar{width:36px;height:36px;border-radius:10px;background:#eef4ff;color:var(--cobalt);font-weight:800;display:flex;align-items:center;justify-content:center;flex:0 0 auto}
  .submission-main{min-width:0;flex:1}
  .submission-main b{display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--navy)}
  .submission-main span{font-size:11px;color:var(--muted)}
  .submission-bottom{display:flex;align-items:center;gap:8px;margin-top:10px;padding-top:9px;border-top:1px dashed var(--line)}
  .submission-score{font-size:12px;color:var(--muted);flex:1}
  .submission-score strong{color:var(--navy)}
  .emptyrecv{text-align:center;color:var(--muted);padding:38px 16px;background:var(--paper);border-radius:12px;border:1px dashed var(--line)}
  .recv-error{background:#fdeeee;color:var(--red);border-radius:10px;padding:11px;font-size:13px}
  .btnrow{display:flex;gap:8px}
  .btnrow .btn{flex:1}
  .countbadge{display:inline-flex;align-items:center;justify-content:center;min-width:20px;height:20px;padding:0 6px;border-radius:999px;background:var(--coral);color:#fff;font-size:11px;margin-left:5px}

  .toast{position:fixed;bottom:96px;left:50%;transform:translateX(-50%);background:var(--navy);color:#fff;
         padding:10px 16px;border-radius:10px;font-size:13px;z-index:80;opacity:0;transition:.25s;pointer-events:none;white-space:nowrap}
  .toast.show{opacity:1}

  /* AI 识别框 */
  .aibox{border:1px solid #cfe0fa;background:linear-gradient(180deg,#f4f8ff,#fff);border-radius:13px;padding:13px;margin-bottom:14px}
  .aihead{display:flex;align-items:center;gap:8px}
  .aibadge{font-size:11px;font-weight:800;color:#fff;background:var(--cobalt);padding:2px 7px;border-radius:6px;letter-spacing:.5px}
  .aistatus{margin-top:10px;font-size:13px;padding:9px 11px;border-radius:9px;display:flex;align-items:center;gap:8px}
  .aistatus.loading{background:#eef4ff;color:var(--cobalt)}
  .aistatus.ok{background:#ecf8f1;color:var(--green)}
  .aistatus.err{background:#fdeeee;color:var(--red)}
  .aispin{width:15px;height:15px;border:2px solid #cfe0fa;border-top-color:var(--cobalt);border-radius:50%;animation:spin .8s linear infinite;flex:0 0 auto}
  @keyframes spin{to{transform:rotate(360deg)}}
  .aithumb{margin-top:10px}
  .aithumb img{max-width:100%;border-radius:9px;border:1px solid var(--line)}
  .setpicker{margin-top:10px}
  .setpicker .lbl{font-size:12px;font-weight:600;color:var(--muted);margin-bottom:7px}
  .setbtn{display:flex;flex-direction:column;align-items:flex-start;gap:2px;width:100%;text-align:left;
          padding:10px 12px;border:1px solid #cfe0fa;border-radius:10px;background:#fff;margin-bottom:7px}
  .setbtn:active{background:#eef4ff}
  .setbtn b{font-size:14px;color:var(--navy)}
  .setbtn span{font-size:12px;color:var(--muted)}

  /* Excel 批量导入 */
  .batchbox{border:1px solid #d7e6d8;background:linear-gradient(180deg,#f4fbf5,#fff);border-radius:13px;padding:13px;margin-bottom:14px}
  .batchhead{display:flex;align-items:center;gap:8px}
  .batchbadge{font-size:11px;font-weight:800;color:#fff;background:var(--green);padding:2px 7px;border-radius:6px;letter-spacing:.5px}
  .batchtools{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-top:10px}
  .batchmode{width:100%;padding:9px 10px;border:1px solid var(--line);border-radius:9px;background:#fff;font-size:13px;color:var(--ink)}
  .batchstatus{margin-top:10px;font-size:12px;padding:9px 11px;border-radius:9px;line-height:1.5}
  .batchstatus.ok{background:#ecf8f1;color:var(--green)}
  .batchstatus.err{background:#fdeeee;color:var(--red)}
  .batchstatus.info{background:#eef4ff;color:var(--cobalt)}
  @media(max-width:520px){.batchtools{grid-template-columns:1fr}}


  /* ===== V12：老师作业库与双评分 ===== */
  .headerlib{padding:6px 10px;border:1px solid var(--line);border-radius:8px;background:var(--card);font-size:12px;font-weight:700;color:var(--navy);white-space:nowrap}
  .headerlib:active{background:var(--paper)}
  .libraryscreen{position:fixed;inset:47px 0 0;background:var(--paper);z-index:24;overflow-y:auto;-webkit-overflow-scrolling:touch;padding:18px 14px 90px}
  .librarywrap{max-width:1080px;margin:0 auto}
  .libraryhero{display:flex;align-items:center;gap:12px;margin-bottom:14px}
  .libraryhero h1{margin:0;color:var(--navy);font-size:22px;line-height:1.2}
  .libraryhero p{margin:4px 0 0;color:var(--muted);font-size:13px}
  .libraryhero .btn{margin-left:auto;min-width:132px}
  .librarytools{display:flex;gap:8px;margin-bottom:12px;position:sticky;top:-18px;z-index:4;padding:10px 0;background:linear-gradient(var(--paper) 78%,rgba(247,246,242,0))}
  .librarysearch{flex:1;min-width:0;padding:11px 13px;border:1px solid var(--line);border-radius:11px;background:#fff;font-size:14px;box-shadow:var(--shadow)}
  .librarysearch:focus{outline:none;border-color:var(--cobalt)}
  .librarystats{display:grid;grid-template-columns:repeat(4,1fr);gap:9px;margin-bottom:14px}
  .libstat{background:#fff;border:1px solid var(--line);border-radius:12px;padding:11px;text-align:center;box-shadow:var(--shadow)}
  .libstat b{display:block;color:var(--navy);font-size:21px}.libstat span{font-size:11px;color:var(--muted)}
  .librarygrid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
  .libcard{background:#fff;border:1px solid var(--line);border-radius:14px;padding:14px;box-shadow:var(--shadow);min-width:0}
  .libcardtop{display:flex;gap:10px;align-items:flex-start}
  .libicon{width:40px;height:46px;border-radius:10px;background:#eef4ff;color:var(--cobalt);display:flex;align-items:center;justify-content:center;font-size:20px;flex:0 0 auto}
  .libtitle{min-width:0;flex:1}.libtitle h3{margin:0;color:var(--navy);font-size:16px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.libtitle p{margin:4px 0 0;color:var(--muted);font-size:11px}
  .libmeta{display:grid;grid-template-columns:repeat(3,1fr);gap:7px;margin:12px 0}
  .libmeta div{background:var(--paper);border-radius:9px;padding:7px;text-align:center;font-size:10px;color:var(--muted)}
  .libmeta b{display:block;color:var(--navy);font-size:15px}
  .libmainactions{display:grid;grid-template-columns:1fr 1fr 1fr;gap:7px;margin-bottom:8px}
  .libmainactions button{padding:9px 7px;border-radius:9px;font-size:12px;font-weight:700}
  .libopen{background:var(--cobalt);color:#fff}.libedit{background:#eef4ff;color:var(--cobalt);border:1px solid #cfe0fa}.libreceive{background:#ecf8f1;color:var(--green);border:1px solid #cfe9da}
  .liblinks{border-top:1px dashed var(--line);padding-top:9px;display:grid;grid-template-columns:repeat(3,1fr);gap:6px}
  .liblinks button,.libfoot button{padding:7px 5px;border:1px solid var(--line);border-radius:8px;background:#fff;font-size:11px;color:var(--muted);font-weight:600}
  .liblinks button:active,.libfoot button:active{background:var(--paper)}
  .libfoot{display:flex;gap:6px;justify-content:flex-end;margin-top:8px}.libfoot .danger{color:var(--red);border-color:#efc5c5}.libfoot .duplicate{color:var(--cobalt)}
  .libraryempty{grid-column:1/-1;padding:54px 18px;text-align:center;color:var(--muted);border:1px dashed var(--line);border-radius:14px;background:#fff}.libraryempty b{display:block;color:var(--navy);font-size:17px;margin-bottom:6px}
  .libraryloading{padding:46px;text-align:center;color:var(--muted)}
  @media(max-width:720px){
    .libraryscreen{inset:47px 0 0;padding:14px 10px 90px}.libraryhero{align-items:flex-start;flex-wrap:wrap}.libraryhero h1{font-size:19px}.libraryhero .btn{width:100%;margin-left:0}
    .librarystats{grid-template-columns:repeat(2,1fr)}.librarygrid{grid-template-columns:1fr}.libmainactions{grid-template-columns:1fr 1fr}.libmainactions .libreceive{grid-column:1/-1}.liblinks{grid-template-columns:1fr 1fr 1fr}
  }


  /* ===== V15：双语、文件夹、题库与智能组卷 ===== */
  .langtoggle{padding:6px 9px;border:1px solid var(--line);border-radius:8px;background:#fff;color:var(--navy);font-size:12px;font-weight:800;white-space:nowrap}
  .libheroactions{display:flex;gap:8px;margin-left:auto}.libheroactions .btn{min-width:128px}
  .setupnotice{display:flex;align-items:center;gap:12px;padding:11px 12px;margin-bottom:12px;border:1px solid #f0d49a;background:#fff8e6;border-radius:12px}.setupnotice div{min-width:0}.setupnotice b,.setupnotice span{display:block}.setupnotice b{color:#875b00}.setupnotice span{font-size:12px;color:var(--muted)}.setupnotice button{margin-left:auto;flex:0 0 auto}
  .folderbar{display:flex;align-items:center;gap:7px;overflow-x:auto;padding:2px 0 10px;scrollbar-width:thin}.folderchip{display:inline-flex;align-items:center;gap:5px;white-space:nowrap;padding:7px 10px;border:1px solid var(--line);border-radius:999px;background:#fff;color:var(--muted);font-size:12px;font-weight:700}.folderchip.on{background:var(--navy);color:#fff;border-color:var(--navy)}.folderchip.add{color:var(--cobalt);border-style:dashed}.folderchip .x{font-size:14px;opacity:.75}
  .libfolder{display:inline-flex;margin:0 0 9px;padding:3px 8px;border-radius:999px;background:#eef4ff;color:var(--cobalt);font-size:11px;font-weight:700}.libfoot .movefolder{color:var(--green)}
  .manager-screen{position:fixed;inset:47px 0 0;background:var(--paper);z-index:26;overflow:auto;padding:18px 14px 80px}.manager-wrap{max-width:1320px;margin:0 auto}.manager-head{display:flex;align-items:center;gap:12px;margin-bottom:14px}.manager-head>div{flex:1}.manager-head h1{margin:0;color:var(--navy);font-size:22px}.manager-head p{margin:3px 0 0;color:var(--muted);font-size:13px}
  .qb-layout{display:grid;grid-template-columns:210px minmax(0,1fr) 310px;gap:12px;align-items:start}.qb-filters,.paper-cart,.qb-main{background:#fff;border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow)}.qb-filters,.paper-cart{position:sticky;top:12px;padding:13px}.qb-filters h3,.paper-cart h3{margin:0 0 10px;color:var(--navy)}.qb-filters input,.qb-filters select,.paper-cart input,.paper-cart select,.question-form input,.question-form select,.question-form textarea{width:100%;padding:9px 10px;margin:0 0 9px;border:1px solid var(--line);border-radius:9px;background:#fff;font:inherit}.qb-main{padding:12px;min-height:430px}.qb-summary{font-size:12px;color:var(--muted);margin:0 0 10px}.qb-list{display:flex;flex-direction:column;gap:9px}.qb-item{display:grid;grid-template-columns:auto minmax(0,1fr) auto;gap:10px;padding:11px;border:1px solid var(--line);border-radius:11px;background:#fff}.qb-item.selected{border-color:var(--cobalt);background:#f7faff}.qb-check{width:20px;height:20px;margin-top:2px}.qb-stem{font-weight:650;color:var(--ink);white-space:pre-wrap}.qb-tags{display:flex;gap:5px;flex-wrap:wrap;margin-top:6px}.qb-tag{padding:2px 6px;border-radius:999px;background:var(--paper);font-size:10px;color:var(--muted)}.qb-actions{display:flex;flex-direction:column;gap:5px}.qb-actions button{padding:5px 8px;border:1px solid var(--line);border-radius:7px;font-size:11px}.qb-actions .delete{color:var(--red)}.qb-head-actions{display:flex;gap:7px;flex-wrap:wrap;margin-left:auto}.qb-head-actions .btn{white-space:nowrap}
  .paper-cart label{display:block;font-size:12px;font-weight:650;color:var(--muted)}.paper-cart .checkline{display:flex;align-items:center;gap:7px;margin:5px 0 10px}.paper-cart .checkline input{width:auto;margin:0}.paper-count{padding:8px;border-radius:9px;background:#eef4ff;color:var(--cobalt);font-size:12px;font-weight:800;text-align:center}.paper-selected{max-height:330px;overflow:auto;margin:9px 0;display:flex;flex-direction:column;gap:6px}.paper-sel-item{display:grid;grid-template-columns:28px 1fr auto;gap:6px;align-items:center;padding:7px;border:1px solid var(--line);border-radius:8px;font-size:11px}.paper-sel-item .num{width:24px;height:24px;border-radius:7px;background:var(--navy);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:800}.paper-sel-item .name{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.paper-sel-item button{padding:2px 5px;border-radius:5px}.paper-cart>.btn{width:100%;margin-top:7px}
  .modal{position:fixed;inset:0;z-index:90;background:rgba(19,41,75,.5);display:flex;align-items:center;justify-content:center;padding:16px}.modal-card{width:min(720px,100%);max-height:92vh;overflow:auto;background:#fff;border-radius:16px;box-shadow:0 18px 60px rgba(0,0,0,.2)}.modal-head,.modal-foot{display:flex;align-items:center;gap:8px;padding:13px 15px;border-bottom:1px solid var(--line)}.modal-head h3{margin:0;color:var(--navy)}.modal-head .tbtn{margin-left:auto}.modal-body{padding:14px}.modal-foot{border-top:1px solid var(--line);border-bottom:none;justify-content:flex-end}.question-form label{display:block;font-size:12px;font-weight:700;color:var(--muted)}.form-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}.paper-print-host{position:fixed;left:-20000px;top:0;width:794px;background:#fff}.paper-sheet{width:794px;min-height:1123px;padding:36px 46px 44px;background:#fff;color:#111;font-family:var(--exercise-font);font-size:15px;line-height:1.75}.paper-brand{text-align:center;font-family:Arial,sans-serif;font-size:10px;letter-spacing:1.6px;color:#666;text-transform:uppercase}.paper-sheet h1{text-align:center;margin:5px 0 16px;font-size:26px;letter-spacing:1px}.paper-info{width:100%;border-collapse:collapse;margin:0 0 13px;font-size:12px}.paper-info td{border:1px solid #333;padding:7px 9px;height:24px}.paper-info td:first-child,.paper-info td:nth-child(3){width:70px;font-weight:700;background:#f4f4f4}.paper-instructions{margin:0 0 20px;padding:9px 12px;border:1px solid #777;background:#fafafa;font-size:12px;line-height:1.55}.paper-section-title{break-after:avoid;margin:22px 0 12px;padding:7px 10px;border-top:2px solid #111;border-bottom:1px solid #777;font-size:17px;font-weight:800}.paper-passage{break-inside:auto;margin:8px 0 18px;padding:15px 18px;border:1px solid #777;border-radius:0;background:#fff}.paper-passage h2{margin:0 0 9px;text-align:center;font-size:18px}.paper-passage .passage-no{text-align:center;font-family:Arial,sans-serif;font-size:11px;font-weight:700;color:#555;margin-bottom:4px}.paper-passage-text p{margin:0 0 .65em;text-indent:2em;text-align:justify;line-height:1.95}.paper-passage-text p:last-child{margin-bottom:0}.paper-question{break-inside:avoid;margin:0 0 19px;padding-bottom:4px;font-size:15px}.paper-question-head{display:grid;grid-template-columns:30px minmax(0,1fr) 74px;gap:3px;align-items:start}.paper-number{font-family:Arial,sans-serif;font-weight:800}.paper-stem{white-space:pre-wrap}.paper-marks{text-align:right;font-family:Arial,sans-serif;font-size:12px;white-space:nowrap}.paper-options{display:grid;grid-template-columns:1fr 1fr;gap:7px 24px;margin:9px 0 0 31px}.paper-option{display:grid;grid-template-columns:22px 1fr;gap:2px;align-items:start}.paper-option-letter{font-family:Arial,sans-serif;font-weight:700}.paper-answer-lines{height:105px;margin:9px 0 0 31px;background:repeating-linear-gradient(to bottom,transparent 0,transparent 25px,#aaa 26px,#aaa 27px)}.paper-answer-key{page-break-before:always}.paper-answer-key h2{text-align:center;margin-bottom:18px}.paper-answer-table{width:100%;border-collapse:collapse;font-size:13px}.paper-answer-table th,.paper-answer-table td{border:1px solid #777;padding:7px;vertical-align:top}.paper-answer-table th{background:#f2f2f2}.paper-page-note{text-align:right;margin-top:16px;font-family:Arial,sans-serif;font-size:10px;color:#666}
  @media(max-width:980px){.qb-layout{grid-template-columns:1fr}.qb-filters,.paper-cart{position:static}.qb-filters{display:grid;grid-template-columns:1fr 1fr;gap:7px}.qb-filters h3,.qb-filters .btn{grid-column:1/-1}.paper-selected{max-height:220px}}
  @media(max-width:720px){.libheroactions{width:100%;margin-left:0}.libheroactions .btn{flex:1;min-width:0}.manager-head{flex-wrap:wrap}.manager-head>div:not(.qb-head-actions){order:-1;flex-basis:100%}.manager-head .btn{flex:1}.qb-head-actions{width:100%;margin-left:0}.qb-head-actions .btn{min-width:0}.form-grid{grid-template-columns:1fr 1fr}.qb-filters{grid-template-columns:1fr}.qb-filters h3,.qb-filters .btn{grid-column:auto}.qb-item{grid-template-columns:auto minmax(0,1fr)}.qb-actions{grid-column:2;flex-direction:row}}


  /* ===== V17：学生档案与错题集 ===== */
  .mistake-layout{display:grid;grid-template-columns:270px minmax(0,1fr);gap:13px;align-items:start}
  .student-panel,.mistake-main{background:#fff;border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow)}
  .student-panel{padding:13px;position:sticky;top:12px}.student-panel h3,.mistake-main h3{margin:0;color:var(--navy)}
  .student-create{padding:10px;margin:11px 0;border-radius:10px;background:var(--paper)}.student-create input{width:100%;padding:8px 9px;border:1px solid var(--line);border-radius:8px;margin:0 0 7px;font:inherit}.student-create .btn{width:100%;padding:8px}
  .student-list{display:flex;flex-direction:column;gap:7px;max-height:58vh;overflow:auto}.student-item{width:100%;display:flex;align-items:center;gap:8px;padding:9px;border:1px solid var(--line);border-radius:9px;background:#fff;text-align:left}.student-item.on{border-color:var(--cobalt);background:#eef4ff}.student-avatar{width:31px;height:31px;border-radius:9px;background:var(--navy);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:800;flex:0 0 auto}.student-info{min-width:0;flex:1}.student-info b,.student-info span{display:block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.student-info span{font-size:10px;color:var(--muted)}.student-count{font-size:11px;color:var(--red);font-weight:800}
  .mistake-main{padding:14px;min-height:430px}.mistake-toolbar{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-bottom:12px}.mistake-toolbar select{padding:8px 9px;border:1px solid var(--line);border-radius:8px;background:#fff}.mistake-toolbar .spacer{flex:1}.mistake-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-bottom:12px}.mistake-stat{padding:10px;border-radius:10px;background:var(--paper);text-align:center}.mistake-stat b{display:block;color:var(--navy);font-size:19px}.mistake-stat span{font-size:10px;color:var(--muted)}
  .mistake-list{display:flex;flex-direction:column;gap:9px}.mistake-card{display:grid;grid-template-columns:auto minmax(0,1fr) auto;gap:10px;padding:12px;border:1px solid var(--line);border-radius:11px;background:#fff}.mistake-card.mastered{opacity:.7}.mistake-card input[type=checkbox]{width:19px;height:19px;margin-top:3px}.mistake-title{font-weight:700;color:var(--ink);white-space:pre-wrap}.mistake-source{font-size:11px;color:var(--muted);margin-top:3px}.mistake-badges{display:flex;gap:5px;flex-wrap:wrap;margin-top:7px}.mistake-badge{padding:2px 7px;border-radius:999px;background:var(--paper);font-size:10px;color:var(--muted);font-weight:700}.mistake-badge.bad{background:#fdeeee;color:var(--red)}.mistake-badge.review{background:#fff4dc;color:#9a6700}.mistake-badge.good{background:#ecf8f1;color:var(--green)}.mistake-answer{margin-top:8px;padding:8px 9px;border-radius:8px;background:#f8fafc;font-size:12px;white-space:pre-wrap}.mistake-answer b{color:var(--navy)}.mistake-actions{display:flex;flex-direction:column;gap:5px}.mistake-actions button{padding:6px 8px;border:1px solid var(--line);border-radius:7px;font-size:11px;white-space:nowrap}.mistake-actions .danger{color:var(--red)}
  .student-code-block{margin-top:9px;padding-top:9px;border-top:1px dashed var(--line)}.student-code-block label{display:block;font-size:11px;font-weight:700;color:var(--muted);margin-bottom:5px}.student-code-row{display:flex;gap:7px}.student-code-row input{flex:1;min-width:0;padding:8px 9px;border:1px solid var(--line);border-radius:8px;font:inherit;text-transform:uppercase}.student-code-row .btn{padding:7px 9px;font-size:11px}.mistake-self-btn{width:100%;margin-top:9px;padding:9px!important}
  .mistake-result{margin:10px 0;padding:10px;border:1px solid #cfe9da;border-radius:9px;background:#ecf8f1;font-size:12px}.mistake-result input{width:100%;margin-top:6px;padding:7px;border:1px solid var(--line);border-radius:7px}
  .manual-mistake{margin-top:10px}.manual-mistake button{padding:7px 10px;border:1px solid #efc5c5;border-radius:8px;color:var(--red);font-size:12px;font-weight:700;background:#fff8f8}
  @media(max-width:820px){.mistake-layout{grid-template-columns:1fr}.student-panel{position:static}.student-list{max-height:230px}.mistake-stats{grid-template-columns:repeat(2,1fr)}.mistake-card{grid-template-columns:auto minmax(0,1fr)}.mistake-actions{grid-column:2;flex-direction:row;flex-wrap:wrap}}


  /* ===== V18：错题集第二阶段 ===== */
  .mistake-head-actions{display:flex;gap:7px;align-items:center;flex-wrap:wrap;justify-content:flex-end}
  .mistake-toolbar .checkline{margin:0;padding:7px 9px;border:1px solid var(--line);border-radius:8px;background:#fff;font-size:12px}
  .mistake-due{color:#a85b00!important;background:#fff1d6!important}
  .mistake-crop-thumb{display:block;max-width:min(520px,100%);max-height:260px;object-fit:contain;margin:9px 0 5px;border:1px solid var(--line);border-radius:9px;background:#f7f7f7}
  .mastery-analysis{margin:12px 0;padding:12px;border:1px solid var(--line);border-radius:11px;background:#fbfcff}
  .mastery-analysis h4{margin:0 0 9px;color:var(--navy)}
  .mastery-row{display:grid;grid-template-columns:minmax(90px,1.4fr) 2fr auto;gap:9px;align-items:center;margin:7px 0;font-size:12px}
  .mastery-label{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-weight:700;color:var(--ink)}
  .mastery-bar{height:9px;border-radius:999px;background:#e7eaf0;overflow:hidden}.mastery-bar i{display:block;height:100%;background:var(--green);border-radius:999px}
  .mastery-numbers{white-space:nowrap;color:var(--muted)}
  .crop-modal .modal-card{width:min(1040px,100%)}
  .crop-tools{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-bottom:10px}.crop-tools .spacer{flex:1}.crop-tools button{padding:7px 10px;border:1px solid var(--line);border-radius:8px}
  .crop-stage-wrap{overflow:auto;max-height:68vh;border:1px solid var(--line);border-radius:11px;background:#d8d8d8;padding:10px}
  .crop-stage{position:relative;width:max-content;max-width:none;margin:auto;background:#fff;box-shadow:var(--shadow)}
  .crop-stage canvas{display:block}.crop-stage #mistakeCropOverlay{position:absolute;inset:0;touch-action:none;cursor:crosshair}
  .crop-manual-fields{display:grid;grid-template-columns:minmax(0,1fr) 120px;gap:10px;margin-top:10px;padding:12px;border:1px solid #d9e2f1;border-radius:12px;background:#f8fbff}
  .crop-manual-fields label{display:grid;gap:5px;font-size:12px;font-weight:700;color:var(--ink)}
  .crop-manual-fields input,.crop-manual-fields textarea{width:100%;box-sizing:border-box;border:1px solid #cbd5e1;border-radius:9px;padding:9px;background:#fff;font:inherit}
  .crop-manual-fields textarea{min-height:66px;resize:vertical}
  .crop-manual-fields .wide{grid-column:1/-1}
  .crop-manual-fields .checkline{display:flex;align-items:center;gap:8px;font-weight:600}
  .crop-manual-fields .checkline input{width:auto}
  @media(max-width:640px){.crop-manual-fields{grid-template-columns:1fr}.crop-manual-fields .wide{grid-column:auto}}
  .crop-hint{font-size:12px;color:var(--muted);margin-top:8px}.crop-hint b{color:var(--cobalt)}
  .mistake-result .result-links{display:grid;gap:7px;margin-top:8px}.mistake-result .result-link-row{display:flex;gap:6px}.mistake-result .result-link-row input{flex:1;min-width:0}
  @media(max-width:820px){.mistake-head-actions{width:100%;justify-content:flex-start}.mastery-row{grid-template-columns:1fr}.mastery-numbers{text-align:left}.crop-stage-wrap{max-height:62vh}}


  /* ===== V19：分层文件夹、阅读材料分组、互动式组卷 ===== */
  .qb-bulkbar{display:flex;gap:7px;align-items:center;flex-wrap:wrap;margin:0 0 10px;padding:8px;border-radius:10px;background:var(--paper)}
  .qb-bulkbar button{padding:7px 10px;border:1px solid var(--line);border-radius:8px;background:#fff;font-size:12px;font-weight:700;color:var(--cobalt)}
  .qb-bulkbar button.danger{color:var(--red);border-color:#efc5c5;background:#fff8f8}.qb-bulkbar button.danger:disabled{opacity:.55;cursor:not-allowed}
  .passage-editor{margin:10px 0;padding:11px;border:1px solid #cfe0fa;border-radius:11px;background:#f7faff}.passage-editor h4{margin:0 0 7px;color:var(--navy);font-size:13px}.passage-editor small{display:block;color:var(--muted);line-height:1.5}
  .qb-passage-badge{display:inline-flex;margin-top:6px;padding:3px 7px;border-radius:999px;background:#fff4dc;color:#8a5b00;font-size:10px;font-weight:800}
  .paper-passage{break-inside:avoid;margin:10px 0 17px;padding:14px 16px;border:1px solid #bbb;border-radius:8px;background:#fafafa;white-space:pre-wrap;line-height:1.75}.paper-passage h2{margin:0 0 8px;font-size:18px;text-align:left}.paper-passage .passage-no{font-size:12px;font-weight:800;color:#555;margin-bottom:5px}
  .interactive-assignment .pdfzone{display:none!important}.interactive-assignment .cardzone{height:100%;max-width:960px;width:100%;margin:0 auto;padding-top:18px}.interactive-assignment .scroll{display:block;overflow:hidden}
  .interactive-stem{margin:0 0 12px;padding:11px 12px;border-radius:10px;background:#f8fafc;border:1px solid #e7ebf0;font-size:15px;font-weight:650;white-space:pre-wrap;line-height:1.65}
  .interactive-options{display:grid;grid-template-columns:1fr;gap:8px}.interactive-options .optbtn{min-height:48px;height:auto;justify-content:flex-start;text-align:left;padding:11px 13px;font-size:14px;font-weight:600;line-height:1.45;white-space:normal}
  .passageblock{margin:4px 0 12px;padding:14px;border:1px solid #cfe0fa;border-radius:13px;background:linear-gradient(180deg,#f7faff,#fff);box-shadow:var(--shadow)}.passageblock h3{margin:0 0 8px;color:var(--navy);font-size:16px}.passageblock .passagecontent{white-space:pre-wrap;line-height:1.8;font-size:14px}.passageblock .passagekey{font-size:11px;font-weight:800;color:var(--cobalt);margin-bottom:5px}
  .folderchip .folderpath{max-width:230px;overflow:hidden;text-overflow:ellipsis}.folderchip.manage{color:var(--green);border-style:dashed}
  @media(max-width:600px){.interactive-assignment .cardzone{padding-left:10px;padding-right:10px}.paper-cart>.btn{font-size:13px}.qb-bulkbar button{flex:1}}

  /* ===== V24：课堂讲评隐藏答案 + 集中重做错题 ===== */
  .reviewcontrols{margin-top:10px;padding:10px 12px;border:1px solid #dce5f2;border-radius:12px;background:#f8fbff;display:flex;align-items:center;gap:8px;flex-wrap:wrap}
  .reviewcontrols>b{font-size:13px;color:var(--navy);margin-right:2px}
  .reviewcontrols .reviewhint{font-size:12px;color:var(--muted);flex:1 1 220px}
  .redobanner{margin:0 0 12px;padding:12px 14px;border-radius:14px;background:#fff7df;border:1px solid #f2d785;color:#6f5200;font-size:13px;line-height:1.55}
  .redobanner b{display:block;color:#5a4200;margin-bottom:2px}
  .redo-original{margin-top:8px;padding:7px 9px;border-radius:9px;background:#f6f7fa;color:var(--muted);font-size:12px}
  .answer-hidden-note{margin-top:8px;padding:8px 10px;border-radius:10px;background:#f7f8fb;border:1px dashed #ccd5e2;color:var(--muted);font-size:12px}
  .reschip.neutral{background:#eef2f7;color:#506077}
  .statuspill.redo{background:#fff1c7;color:#7a5700}



  /* ===== V24：移动端工具栏、正式试卷排版、单链接与课堂资料切换 ===== */
  .libmainactions{grid-template-columns:1fr}
  .liblinks{grid-template-columns:1fr}
  .libmainactions .libopen,.liblinks button{min-height:42px}
  .lesson-resource-list{display:flex;flex-direction:column;gap:8px;margin-top:10px}
  .lesson-resource-item{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:10px;align-items:center;padding:11px 12px;border:1px solid var(--line);border-radius:11px;background:#fff}
  .lesson-resource-item b{display:block;color:var(--navy);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
  .lesson-resource-item small{display:block;color:var(--muted);margin-top:2px}
  .lesson-resource-item.active{border-color:var(--cobalt);background:#f5f8ff}
  .lesson-resource-empty{padding:18px;text-align:center;color:var(--muted);border:1px dashed var(--line);border-radius:11px}
  .lesson-resource-search{width:100%;padding:10px 11px;border:1px solid var(--line);border-radius:9px;font:inherit}
  .lesson-resource-upload{margin-top:12px;padding-top:12px;border-top:1px solid var(--line)}

  /* A4 由内容本身留边，不再叠加 html2pdf 外边距，避免分值及右侧文字被裁掉。 */
  .paper-print-host{width:794px}
  .paper-sheet{width:794px;min-height:1123px;padding:34px 48px 42px;overflow:hidden;font-size:15px;line-height:1.72}
  .paper-sheet *{box-sizing:border-box}
  .paper-section-title{margin:24px 0 13px;padding:8px 5px 7px;border-top:2.5px solid #111;border-bottom:1px solid #888;font-size:18px}
  .paper-passage{width:100%;max-width:100%;overflow:hidden;margin:9px 0 18px;padding:14px 16px;page-break-inside:auto}
  .paper-passage-text{max-width:100%;overflow-wrap:anywhere}
  .paper-question{width:100%;max-width:100%;margin:0 0 20px;padding:0 1px 4px;break-inside:avoid;page-break-inside:avoid}
  .paper-question-head{display:grid;grid-template-columns:31px minmax(0,1fr) 58px;column-gap:5px;align-items:start;width:100%}
  .paper-number{font-weight:800;white-space:nowrap}
  .paper-stem{min-width:0;white-space:pre-wrap;overflow-wrap:anywhere}
  .paper-marks{text-align:right;font-family:Arial,sans-serif;font-size:11px;line-height:1.25;white-space:normal;overflow-wrap:anywhere;padding-top:2px}
  .paper-options{display:grid;grid-template-columns:1fr 1fr;gap:7px 22px;margin:10px 2px 0 34px}
  .paper-options.cloze{grid-template-columns:1fr;gap:5px;margin-left:42px}
  .paper-option{display:grid;grid-template-columns:31px minmax(0,1fr);gap:3px;align-items:start;min-width:0}
  .paper-option-letter{font-family:Arial,sans-serif;font-weight:700;white-space:nowrap}
  .paper-option span:last-child{min-width:0;overflow-wrap:anywhere}
  .paper-option-bank{margin:8px 0 15px;padding:12px 14px;border:1px solid #888;display:grid;grid-template-columns:1fr 1fr;gap:7px 20px;page-break-inside:avoid}
  .paper-option-bank .paper-option{grid-template-columns:24px minmax(0,1fr)}
  .paper-dialogue-label{font-weight:800;margin:12px 0 7px}
  .paper-answer-lines{height:auto;margin:9px 2px 0 34px;background:none}
  .paper-answer-line{height:27px;border-bottom:1px solid #999}
  .paper-question.dialogue-question{margin-bottom:12px}
  .paper-question.dialogue-question .paper-options{display:none}

  @media(max-width:720px){
    .manager-head{display:block!important}
    .manager-head>div:not(.qb-head-actions){width:100%;margin-bottom:10px}
    .qb-head-actions{display:grid!important;grid-template-columns:1fr 1fr;width:100%;margin:0!important;gap:8px}
    .qb-head-actions .btn{width:100%;min-width:0;min-height:46px;padding:9px 6px;white-space:normal!important;line-height:1.25;text-align:center}
    .qb-head-actions #qbAddQuestion{grid-column:1/-1}
    .question-bank-screen{padding-left:12px!important;padding-right:12px!important;overflow-x:hidden}
    .libmainactions,.liblinks{grid-template-columns:1fr!important}
  }



  /* ===== V26：错题批量定位、学生错题集宽屏布局 ===== */
  .crop-wrong-panel{margin:0 0 12px;padding:11px;border:1px solid #cfe0fa;border-radius:12px;background:#f7faff}
  .crop-wrong-head{display:flex;gap:8px;align-items:center;flex-wrap:wrap}.crop-wrong-head b{color:var(--navy)}
  .crop-wrong-head .spacer{flex:1}.crop-wrong-head button{padding:6px 9px;border:1px solid var(--line);border-radius:8px;background:#fff;font-size:12px;font-weight:700}
  .crop-wrong-list{display:flex;gap:7px;flex-wrap:wrap;margin-top:9px;max-height:150px;overflow:auto}
  .crop-wrong-item{display:grid;grid-template-columns:auto minmax(0,1fr);gap:7px;align-items:start;min-width:190px;max-width:310px;padding:8px 9px;border:1px solid #d8e2ef;border-radius:9px;background:#fff;cursor:pointer;text-align:left}
  .crop-wrong-item.on{border-color:var(--cobalt);box-shadow:0 0 0 2px rgba(36,86,196,.1)}
  .crop-wrong-item.located{background:#f3fbf6;border-color:#bde4cc}.crop-wrong-item.missing{background:#fffaf0;border-color:#eed9a5}
  .crop-wrong-item input{width:18px;height:18px;margin-top:2px}.crop-wrong-copy{min-width:0}.crop-wrong-copy b,.crop-wrong-copy span,.crop-wrong-copy small{display:block}
  .crop-wrong-copy b{color:var(--navy);font-size:12px}.crop-wrong-copy span{font-size:11px;color:var(--muted);margin-top:2px}.crop-wrong-copy small{font-size:10px;margin-top:4px;color:#8a5b00}
  .crop-wrong-note{font-size:11px;color:var(--muted);line-height:1.55;margin-top:8px}.crop-wrong-note strong{color:var(--cobalt)}
  .mistake-screen-student .mistake-layout{grid-template-columns:minmax(0,1fr)}
  .mistake-screen-student .mistake-main{grid-column:1/-1;width:100%;min-width:0;box-sizing:border-box}
  .mistake-screen-student .mistake-stats{grid-template-columns:repeat(5,minmax(95px,1fr))}
  .student-code-help{font-size:11px;color:var(--muted);line-height:1.45;margin-top:6px}
  @media(max-width:900px){.mistake-screen-student .mistake-stats{grid-template-columns:repeat(2,minmax(0,1fr))}.crop-wrong-item{min-width:160px;max-width:100%}}


  /* ===== V27：更大的批注工具、画笔粗细、直线与画圈 ===== */
  .annobtns{align-items:center;gap:5px}
  .tbtn{width:38px;height:38px;border-radius:9px;flex:0 0 auto}
  .tbtn svg{width:22px;height:22px}
  .csw{width:22px;height:22px;cursor:pointer;flex:0 0 auto}
  .anno-divider{width:5px;height:1px;flex:0 0 auto}
  .anno-width-wrap{display:flex;align-items:center;gap:4px;padding:3px 6px;border:1px solid var(--line);border-radius:9px;background:#fff;font-size:10px;color:var(--muted);white-space:nowrap}
  .anno-width-wrap select{border:0;outline:0;background:transparent;color:var(--navy);font:700 12px inherit;min-width:38px;padding:4px 1px}
  .subject-category-note{margin:8px 0 12px;padding:9px 12px;border-left:3px solid var(--green);border-radius:8px;background:#f1faf5;color:#40506a;font-size:12px;line-height:1.65}
  .subject-category-note b{color:var(--navy)}
  .mistake-badge.category{background:#eef4ff;color:var(--cobalt);font-size:11px}
  @media (pointer:coarse), (max-width:900px){
    .pdfbar{padding:7px 8px;gap:6px}
    .annobtns{gap:6px;width:100%;overflow-x:auto;flex-wrap:nowrap;padding:1px 0 3px;scrollbar-width:none}
    .annobtns::-webkit-scrollbar{display:none}
    .tbtn{width:44px;height:44px;border-radius:11px}
    .tbtn svg{width:25px;height:25px}
    .csw{width:26px;height:26px}
    .anno-width-wrap{height:42px;padding:4px 8px;font-size:11px}
    .anno-width-wrap select{font-size:14px;min-width:44px}
  }


/* ===== V28：班级实时课堂、批注清空与稳定双语 ===== */
.classroom-bulk-controls{margin:10px 0 12px;padding:11px;border:1px solid #cfe0fa;border-radius:12px;background:#f7faff;display:flex;align-items:center;gap:9px;flex-wrap:wrap}
.classroom-bulk-controls label{display:flex;align-items:center;gap:7px;font-size:13px;font-weight:700;color:var(--navy)}
.classroom-bulk-controls .class-count{margin-left:auto;font-size:12px;color:var(--muted);font-weight:700}
.class-pick{display:flex;align-items:center;justify-content:center;width:30px;height:30px;flex:0 0 30px;border-radius:8px;background:#eef4ff}
.class-pick input{width:18px;height:18px}
.submission-card.v28-selected{border-color:#7da3ee;box-shadow:0 0 0 2px rgba(36,86,196,.1)}
.class-roster{margin:8px 0;padding:9px 10px;border:1px solid #cfe0fa;border-radius:10px;background:#f7faff;font-size:12px;color:var(--muted);display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.class-roster b{color:var(--navy)}
.class-roster .class-chip{padding:4px 8px;border-radius:999px;background:#fff;border:1px solid #d9e4f7;color:var(--navy)}
.class-permission-list{display:grid;gap:8px;margin-top:10px}
.class-permission-row{display:flex;align-items:center;gap:10px;padding:10px;border:1px solid var(--line);border-radius:10px;background:#fff}
.class-permission-row input{width:19px;height:19px}
.class-permission-row span{flex:1;font-weight:700;color:var(--navy)}
.class-permission-row small{color:var(--muted)}
.student-mistake-actions{margin-top:9px;display:flex;gap:8px;flex-wrap:wrap}
.student-mistake-actions .btn{padding:8px 10px;font-size:12px}
.class-answer-reveal{margin-top:8px;padding:8px 10px;border-radius:8px;background:#eaf7ef;color:#157a45;font-size:12px;font-weight:700}
@media(max-width:720px){
 .classroom-bulk-controls{align-items:stretch}.classroom-bulk-controls .btn{flex:1 1 42%}.classroom-bulk-controls .class-count{width:100%;margin-left:0;text-align:center}
 .class-pick{width:36px;height:36px;flex-basis:36px}
}



  /* V28.3：像 Kami 一样直接在 PDF 上建立、拖动和调整文字框。 */
  .pdf-text-editor{position:absolute;z-index:12;min-width:130px;min-height:82px;border:2px solid #8b3fd6;border-radius:6px;background:rgba(255,255,255,.96);box-shadow:0 8px 24px rgba(76,29,149,.22);display:flex;flex-direction:column;overflow:visible;touch-action:none}
  .pdf-text-editor textarea{display:block;flex:1 1 auto;width:100%;height:auto;min-height:0;box-sizing:border-box;border:0;outline:0;resize:none;padding:8px 10px;background:transparent;color:inherit;font-family:Arial,"KaiTi","STKaiti",sans-serif;line-height:1.28;overflow:auto;touch-action:manipulation;-webkit-user-select:text;user-select:text}
  .pdf-text-toolbar{height:32px;flex:0 0 32px;display:flex;align-items:center;gap:4px;padding:3px 5px;background:#f3e8ff;border-bottom:1px solid #d8b4fe;cursor:move;touch-action:none;user-select:none;-webkit-user-select:none}
  .pdf-text-toolbar .dragmark{font:900 15px/1 Arial;color:#6b21a8;padding:0 3px;letter-spacing:-1px}
  .pdf-text-toolbar button{height:25px;min-width:27px;padding:0 6px;border-radius:5px;border:1px solid #d8b4fe;background:#fff;color:#4c1d95;font:700 12px/1 Arial,sans-serif}
  .pdf-text-toolbar button.primary{background:#7e22ce;color:#fff;border-color:#7e22ce}
  .pdf-text-toolbar button.danger{color:#b42318}
  .pdf-text-toolbar .size-label{min-width:38px;text-align:center;color:#4c1d95;font:700 11px/1 Arial,sans-serif}
  .pdf-text-toolbar .color-dot{width:20px;height:20px;border-radius:50%;border:2px solid #fff;box-shadow:0 0 0 1px #c4b5fd;flex:0 0 auto}
  .pdf-text-toolbar .color-dot.on{box-shadow:0 0 0 2px #6d28d9}
  .pdf-text-resize{position:absolute;right:-7px;bottom:-7px;width:18px;height:18px;border-radius:50%;background:#7e22ce;border:2px solid #fff;box-shadow:0 1px 5px rgba(0,0,0,.25);cursor:nwse-resize;touch-action:none}
  .pdf-text-hint{position:absolute;left:0;top:100%;margin-top:7px;padding:4px 7px;border-radius:5px;background:rgba(19,41,75,.9);color:#fff;font-size:10px;white-space:nowrap;pointer-events:none}
  @media(max-width:820px){.pdf-text-editor{min-width:150px}.pdf-text-toolbar{height:38px;flex-basis:38px;gap:5px}.pdf-text-toolbar button{height:30px;min-width:31px;font-size:13px}.pdf-text-toolbar .color-dot{width:23px;height:23px}.pdf-text-resize{width:22px;height:22px;right:-9px;bottom:-9px}}

  /* ===== V28.4：Google 老师登录 ===== */
  .authgate{position:fixed;inset:0;z-index:9999;background:linear-gradient(145deg,#f7f6f2 0%,#eef4ff 55%,#fff 100%);display:flex;align-items:center;justify-content:center;padding:24px}
  .authcard{width:min(430px,100%);background:#fff;border:1px solid var(--line);border-radius:22px;box-shadow:0 18px 60px rgba(19,41,75,.14);padding:30px;text-align:center}
  .authmark{width:62px;height:54px;border-radius:14px;background:var(--navy);margin:0 auto 18px;position:relative;box-shadow:0 10px 24px rgba(19,41,75,.18)}
  .authmark:after{content:"";position:absolute;right:8px;top:8px;width:11px;height:11px;border-radius:50%;background:var(--green)}
  .authcard h1{margin:0;color:var(--navy);font-size:25px;line-height:1.25}
  .authcard .authsub{margin:9px 0 22px;color:var(--muted);font-size:14px}
  .googlelogin{width:100%;display:flex;align-items:center;justify-content:center;gap:11px;padding:13px 16px;border:1px solid #d7dbe3;border-radius:12px;background:#fff;font-size:15px;font-weight:700;box-shadow:0 2px 8px rgba(19,41,75,.06)}
  .googlelogin:hover{background:#f8faff}.googlelogin:disabled{opacity:.55;cursor:wait}
  .googlelogin .gicon{width:21px;height:21px;display:grid;place-items:center;font:900 19px/1 Arial;color:#4285f4}
  .authhint{margin-top:17px;padding-top:15px;border-top:1px solid var(--line);font-size:12px;color:var(--muted);line-height:1.65}
  .autherror{display:none;margin-top:12px;padding:9px 10px;border-radius:9px;background:#fdeeee;color:var(--red);font-size:12px;text-align:left}
  .authuser{display:flex;align-items:center;gap:7px;min-width:0;max-width:230px;padding:3px 6px 3px 3px;border:1px solid var(--line);border-radius:999px;background:var(--paper)}
  .authuser img,.authavatar{width:27px;height:27px;border-radius:50%;object-fit:cover;background:#dfe7f5;display:grid;place-items:center;color:var(--navy);font-size:11px;font-weight:800;flex:0 0 auto}
  .authwho{min-width:0;line-height:1.15}.authwho b,.authwho small{display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.authwho b{font-size:10px;color:var(--navy)}.authwho small{font-size:9px;color:var(--muted);margin-top:2px}
  .authlogout{width:25px;height:25px;border-radius:50%;font-size:14px;color:var(--muted);flex:0 0 auto}.authlogout:hover{background:#fff;color:var(--red)}
  .authmigrating{margin-top:12px;color:var(--cobalt);font-size:12px;font-weight:700}
  @media(max-width:720px){.authwho{display:none}.authuser{padding-right:3px}.authcard{padding:25px 20px}.authcard h1{font-size:22px}}