:root{
  --bg:#f5f7fa; --panel:#ffffff; --ink:#1f2937; --muted:#6b7280;
  --line:#e5e7eb; --primary:#0d9488; --primary-d:#0f766e;
  --accent:#2563eb; --warn:#dc2626; --ok:#16a34a;
  --chip:#eef2f7; --shadow:0 1px 3px rgba(0,0,0,.08),0 4px 16px rgba(0,0,0,.05);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;height:100%}
body{
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;
  background:var(--bg); color:var(--ink); font-size:16px; line-height:1.6;
}
.topbar{
  position:sticky; top:0; z-index:30; display:flex; align-items:center; gap:12px;
  height:56px; padding:0 14px; background:var(--primary); color:#fff; box-shadow:var(--shadow);
}
.menu-btn{display:none; background:none; border:none; color:#fff; font-size:24px; cursor:pointer; padding:4px 8px; border-radius:8px}
.menu-btn:hover{background:rgba(255,255,255,.15)}
.brand{font-weight:700; font-size:18px; white-space:nowrap}
.search-box{margin-left:auto; display:flex; gap:6px; flex:1; max-width:460px}
.search-box input{
  flex:1; padding:8px 12px; border:none; border-radius:8px; font-size:15px; outline:none;
}
.search-box button{background:#fff; color:var(--primary-d); border:none; padding:0 14px; border-radius:8px; font-weight:600; cursor:pointer}
.layout{display:flex; min-height:calc(100vh - 56px)}
.sidebar{
  width:290px; flex:0 0 290px; background:var(--panel); border-right:1px solid var(--line);
  height:calc(100vh - 56px); position:sticky; top:56px; overflow-y:auto; padding:8px 0;
}
.nav-group{border-bottom:1px solid var(--line)}
.group-title{
  padding:12px 16px; font-weight:700; cursor:pointer; user-select:none;
  display:flex; align-items:center; justify-content:space-between; background:var(--chip); color:var(--primary-d);
}
.group-title::after{content:"▾"; font-size:12px; color:var(--muted)}
.group-title.collapsed::after{content:"▸"}
.group-body{display:block; padding:4px 0}
.group-body.hidden{display:none}
.subj{border-left:3px solid transparent}
.subj>.subj-head{
  padding:9px 16px; cursor:pointer; font-weight:600; display:flex; justify-content:space-between; align-items:center;
}
.subj>.subj-head:hover{background:var(--bg)}
.subj.open{border-left-color:var(--primary)}
.subj-body{display:none; padding:2px 0 6px}
.subj.open>.subj-body{display:block}
.chapter{padding:6px 16px 6px 24px; cursor:pointer; color:var(--ink); display:flex; align-items:center; gap:6px}
.chapter:hover{background:var(--bg); color:var(--primary-d)}
.chapter .pg{margin-left:auto; font-size:12px; color:var(--muted)}
.section{padding:5px 16px 5px 40px; cursor:pointer; font-size:14px; color:var(--muted)}
.section:hover{color:var(--primary-d); background:var(--bg)}
.point-item{padding:7px 16px 7px 24px; cursor:pointer; font-size:14px; display:flex; gap:6px; align-items:flex-start}
.point-item:hover{background:var(--bg); color:var(--primary-d)}
.point-item .pid{color:var(--primary); font-weight:700; flex:0 0 auto}
.done-mark{margin-left:auto; color:var(--ok); font-size:13px}
.content{flex:1; padding:18px; max-width:1000px; width:100%}
.welcome{max-width:760px; margin:0 auto; text-align:center; padding-top:30px}
.welcome h1{color:var(--primary-d)}
.welcome-cards{display:grid; grid-template-columns:repeat(2,1fr); gap:14px; margin:24px 0}
.wcard{background:var(--panel); border:1px solid var(--line); border-radius:14px; padding:18px; cursor:pointer; text-align:left; box-shadow:var(--shadow); transition:transform .12s}
.wcard:hover{transform:translateY(-3px); border-color:var(--primary)}
.wcard b{display:block; font-size:17px; color:var(--primary-d); margin-bottom:4px}
.wcard span{color:var(--muted); font-size:14px}
.tip{color:var(--muted); font-size:14px}

.reader-head{display:flex; align-items:center; flex-wrap:wrap; gap:10px; margin-bottom:12px}
.reader-head h2{margin:0; font-size:19px; color:var(--primary-d)}
.reader-head .nav-bt{margin-left:auto; display:flex; gap:8px}
.reader-head button{background:var(--panel); border:1px solid var(--line); padding:7px 12px; border-radius:8px; cursor:pointer; font-size:14px}
.reader-head button:hover{border-color:var(--primary); color:var(--primary-d)}
.reader-head button:disabled{opacity:.4; cursor:not-allowed}
.page-img{width:100%; max-width:900px; margin:0 auto 14px; display:block; border:1px solid var(--line); border-radius:8px; background:#fff; box-shadow:var(--shadow)}
.chapter-nav{display:flex; justify-content:space-between; margin:10px 0 24px; gap:10px}
.chapter-nav button{flex:1; padding:10px; border:1px solid var(--line); border-radius:10px; background:var(--panel); cursor:pointer; font-size:15px}
.chapter-nav button:hover{border-color:var(--primary); color:var(--primary-d)}

/* 内容页顶部工具条：吸顶，返回/翻页常驻 */
.reader-head{position:sticky; top:56px; z-index:10; background:var(--bg); padding:8px 0; margin-bottom:12px; border-bottom:1px solid var(--line)}
.reader-head h2{flex:1; min-width:0; margin:0; font-size:19px; color:var(--primary-d)}
.reader-head .back-btn{background:var(--panel); border:1px solid var(--primary); color:var(--primary-d); padding:7px 12px; border-radius:8px; cursor:pointer; font-size:14px; font-weight:600; white-space:nowrap}
.reader-head .back-btn:hover{background:var(--primary); color:#fff}
.reader-head .done-btn{background:var(--panel); border:1px solid var(--line); padding:7px 12px; border-radius:8px; cursor:pointer; font-size:14px; white-space:nowrap}
.reader-head .done-btn.on{background:var(--ok); border-color:var(--ok); color:#fff; font-weight:600}

/* 内容页「☰ 目录」按钮：默认隐藏，仅手机端显示 */
.cat-btn{display:none}
.reader-head .cat-btn{
  background:var(--primary); border:1px solid var(--primary); color:#fff;
  padding:7px 12px; border-radius:8px; cursor:pointer; font-size:14px; font-weight:600; white-space:nowrap;
}
.reader-head .cat-btn:hover{background:var(--primary-d); border-color:var(--primary-d); color:#fff}

/* 内容页内的“返回目录”列表 */
.toc-list{display:flex; flex-direction:column; gap:8px; max-width:860px}
.toc-item{display:flex; align-items:center; gap:10px; padding:12px 14px; background:var(--panel); border:1px solid var(--line); border-radius:10px; cursor:pointer; box-shadow:var(--shadow)}
.toc-item:hover{border-color:var(--primary); color:var(--primary-d)}
.toc-item.done{background:#f0fdf4; border-color:#bbf7d0}
.toc-idx{flex:0 0 auto; width:30px; text-align:center; font-weight:700; color:var(--primary); background:var(--chip); border-radius:6px; padding:2px 0; font-size:14px}
.toc-title{flex:1; min-width:0; font-size:15px; overflow:hidden; text-overflow:ellipsis; white-space:nowrap}
.toc-pg{margin-left:auto; font-size:12px; color:var(--muted); flex:0 0 auto}
.toc-sub{padding:8px 14px 8px 56px; cursor:pointer; font-size:14px; color:var(--muted); border-left:2px solid var(--line); margin-left:8px}
.toc-sub:hover{color:var(--primary-d); background:var(--bg)}

.point-card{background:var(--panel); border:1px solid var(--line); border-radius:14px; padding:22px; box-shadow:var(--shadow); max-width:860px; margin:0 auto}
.point-q{font-size:18px; font-weight:700; color:var(--primary-d); margin-bottom:14px; white-space:pre-wrap}
.point-a{background:var(--bg); border-left:4px solid var(--primary); border-radius:8px; padding:14px 16px; white-space:pre-wrap; font-size:16px}
.mnemonic{margin-top:12px; padding:10px 14px; background:#fff5f5; border-left:4px solid #d92b2b; border-radius:8px; color:#d92b2b; font-weight:700; font-size:16px; white-space:pre-wrap}
.point-a.hide{filter:blur(6px); user-select:none}
.toggle-a{margin-top:12px; background:var(--primary); color:#fff; border:none; padding:9px 16px; border-radius:8px; cursor:pointer; font-size:15px}
.tag{display:inline-block; background:#fffbeb; color:#92400e; border:1px solid #fde68a; font-size:12px; padding:2px 8px; border-radius:6px; margin-left:8px; font-weight:600}
.src{display:inline-block; color:var(--muted); font-size:12px; margin-left:8px; font-weight:400}

.q-card{background:var(--panel); border:1px solid var(--line); border-radius:12px; padding:16px 18px; margin-bottom:16px; box-shadow:var(--shadow)}
.q-card .qno{font-weight:700; color:var(--primary-d); margin-right:6px}
.q-card .qtype{font-size:12px; background:var(--chip); color:var(--muted); padding:2px 8px; border-radius:6px; margin-left:8px}
.q-stem{margin:8px 0 12px; white-space:pre-wrap; font-size:16px}
.opt{display:block; padding:9px 12px; border:1px solid var(--line); border-radius:8px; margin:6px 0; cursor:pointer}
.opt:hover{border-color:var(--primary)}
.opt.sel{background:#e0f2f1; border-color:var(--primary)}
.opt.correct{background:#dcfce7; border-color:var(--ok)}
.opt.wrong{background:#fee2e2; border-color:var(--warn)}
.opt input{margin-right:10px}
.feedback{margin-top:10px; font-size:14px; white-space:pre-wrap}
.feedback .ok{color:var(--ok); font-weight:700}
.feedback .bad{color:var(--warn); font-weight:700}
.explain{background:var(--bg); border-radius:8px; padding:10px 12px; margin-top:8px; color:var(--muted); white-space:pre-wrap}

.test-config{background:var(--panel); border:1px solid var(--line); border-radius:14px; padding:22px; max-width:520px; box-shadow:var(--shadow)}
.test-config h2{margin-top:0; color:var(--primary-d)}
.test-config label{display:block; margin:14px 0 6px; font-weight:600}
.test-config select{padding:9px 12px; border:1px solid var(--line); border-radius:8px; font-size:15px; width:100%}
.btn-primary{background:var(--primary); color:#fff; border:none; padding:11px 20px; border-radius:10px; font-size:16px; cursor:pointer; margin-top:18px; width:100%}
.btn-primary:hover{background:var(--primary-d)}
.score-bar{background:var(--panel); border:1px solid var(--line); border-radius:14px; padding:18px; margin-bottom:18px; text-align:center; box-shadow:var(--shadow)}
.score-bar .big{font-size:34px; font-weight:800; color:var(--primary-d)}

.search-results .sres{padding:12px 14px; border:1px solid var(--line); border-radius:10px; margin-bottom:10px; cursor:pointer; background:var(--panel)}
.search-results .sres:hover{border-color:var(--primary)}
.search-results .stag{font-size:12px; color:#fff; background:var(--accent); padding:2px 8px; border-radius:6px; margin-right:8px}
.search-results .snip{color:var(--muted); font-size:14px; margin-top:6px; white-space:pre-wrap}
.empty-hint{color:var(--muted); padding:12px 16px; font-size:14px}
.bank-note{background:#fffbeb; border:1px solid #fde68a; color:#92400e; padding:12px 14px; border-radius:10px; margin-bottom:14px; font-size:14px}
.overlay{display:none; position:fixed; inset:0; background:rgba(0,0,0,.35); z-index:20}
.overlay.show{display:block}

@media (max-width:820px){
  .menu-btn{display:block}
  .brand{font-size:16px}
  .search-box{max-width:none}
  .sidebar{
    position:fixed; left:0; top:56px; bottom:0; transform:translateX(-100%);
    transition:transform .2s; z-index:25; box-shadow:var(--shadow); width:68%; max-width:260px;
  }
  .sidebar.open{transform:translateX(0)}
  /* 手机端内容区占满整屏，点开内容后侧边栏自动收起 */
  .content{padding:12px; max-width:100%}
  .welcome-cards{grid-template-columns:1fr}

  /* 手机端显示「☰ 目录」按钮 */
  .cat-btn{display:inline-block}

  /* 内容页顶部工具条：小屏换行排布，按钮不挤成一团 */
  .reader-head{gap:8px}
  .reader-head .cat-btn{order:1; padding:6px 10px; font-size:13px}
  .reader-head .back-btn{order:1; padding:6px 10px; font-size:13px}
  .reader-head h2{order:2; flex-basis:100%; font-size:17px}
  .reader-head .nav-bt{order:3; margin-left:0; width:100%; flex-wrap:wrap}
  .reader-head button{padding:6px 10px; font-size:13px}
  .page-img{max-width:100%}
  .point-card{padding:16px}
  .point-q{font-size:17px}
  .point-a{font-size:17px; line-height:1.75}
}

/* 版本号显示：方便用户确认自己看到的是哪一版 */
.app-ver{margin-top:10px;font-size:12px;color:#9aa5ad;letter-spacing:.3px}
.side-foot{padding:10px 16px 16px;font-size:11px;color:#9aa5ad;border-top:1px solid #eceff1;margin-top:auto}