/* precision.css — AI 精准学（网页版学习机核心闭环） */
/* ⚠ 变量约定：本文件同时被 PC 端（pc.css）与移动端（app.css）加载。
   pc.css 只有 --bg-raise、没有 --card / --bg2，所以这里一律写成
   var(--card, var(--bg-raise)) 形式，否则 PC 端卡片背景会变透明。 */

/* ===== 选科/年级/单元 ===== */
.pz-wrap { max-width: 920px; margin: 0 auto; padding: 8px 0 40px; }
.pz-back { display: inline-flex; align-items: center; gap: 6px; color: var(--muted); font-size: 13px; cursor: pointer; padding: 6px 10px; border-radius: 10px; }
.pz-back:hover { background: var(--card, var(--bg-raise)); color: var(--ink); }
.pz-title { font-size: 22px; font-weight: 800; margin: 6px 0 2px; }
.pz-sub { color: var(--muted); font-size: 13.5px; margin-bottom: 18px; }
.pz-sec { font-size: 14px; font-weight: 700; color: var(--muted); margin: 22px 0 10px; letter-spacing: .5px; }
.pz-chips { display: flex; flex-wrap: wrap; gap: 10px; }
.pz-chip { padding: 9px 16px; border-radius: 12px; background: var(--card, var(--bg-raise)); border: 1px solid var(--line); color: var(--ink); font-size: 14px; cursor: pointer; transition: .15s; }
.pz-chip:hover { border-color: var(--brand); }
.pz-chip.on { background: var(--brand); border-color: var(--brand); color: #fff; font-weight: 700; }
.pz-units { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px; margin-top: 8px; }
.pz-unit { background: var(--card, var(--bg-raise)); border: 1px solid var(--line); border-radius: 16px; padding: 18px 18px 16px; cursor: pointer; transition: .15s; position: relative; overflow: hidden; }
.pz-unit:hover { transform: translateY(-2px); border-color: var(--brand); box-shadow: 0 8px 24px rgba(0,0,0,.25); }
.pz-unit .pu-ic { font-size: 26px; }
.pz-unit .pu-name { font-size: 15.5px; font-weight: 700; margin: 8px 0 4px; }
.pz-unit .pu-meta { font-size: 12.5px; color: var(--muted); }
.pz-unit .pu-go { margin-top: 12px; font-size: 13px; color: var(--brand); font-weight: 700; }
.pz-unit .pu-tag { position: absolute; top: 12px; right: 12px; font-size: 11px; padding: 3px 8px; border-radius: 999px; background: rgba(124,109,255,.16); color: #b9b0ff; }

/* ===== 诊断 / 针对练 答题 ===== */
.pz-quiz { max-width: 640px; margin: 0 auto; padding: 8px 0 40px; }
.pz-prog { height: 8px; background: var(--card, var(--bg-raise)); border-radius: 999px; overflow: hidden; margin: 10px 0 4px; }
.pz-prog > i { display: block; height: 100%; background: var(--brand); border-radius: 999px; transition: width .25s; }
.pz-prog-t { font-size: 12.5px; color: var(--muted); margin-bottom: 18px; }
.pz-q { font-size: 19px; font-weight: 700; line-height: 1.55; margin-bottom: 20px; }
.pz-opts { display: grid; gap: 12px; }
.pz-opt { display: flex; align-items: center; gap: 12px; padding: 15px 16px; background: var(--card, var(--bg-raise)); border: 1.5px solid var(--line); border-radius: 14px; cursor: pointer; font-size: 15.5px; transition: .12s; }
.pz-opt:hover { border-color: var(--brand); }
.pz-opt .dot { width: 26px; height: 26px; flex: none; border-radius: 50%; background: var(--bg-side, var(--card, var(--bg-raise))); display: grid; place-items: center; font-size: 13px; color: var(--muted); font-weight: 700; }
.pz-opt.correct { border-color: #34d399; background: rgba(52,211,153,.14); }
.pz-opt.correct .dot { background: #34d399; color: #043; }
.pz-opt.wrong { border-color: #f87171; background: rgba(248,113,113,.14); }
.pz-opt.wrong .dot { background: #f87171; color: #410; }
.pz-opt.locked { pointer-events: none; }
.pz-feed { margin-top: 16px; font-size: 14.5px; font-weight: 700; min-height: 22px; }
.pz-feed.ok { color: #34d399; }
.pz-feed.no { color: #f87171; }
.pz-next { margin-top: 14px; display: inline-flex; align-items: center; gap: 6px; padding: 11px 22px; border-radius: 12px; background: var(--brand); color: #fff; font-weight: 700; cursor: pointer; border: none; font-size: 15px; }
.pz-next:disabled { opacity: .5; cursor: default; }

/* ===== 知识图谱 ===== */
.pz-graph { max-width: 840px; margin: 0 auto; padding: 8px 0 40px; }
.pz-summary { display: flex; gap: 12px; flex-wrap: wrap; margin: 14px 0 22px; }
.pz-sum { flex: 1; min-width: 120px; background: var(--card, var(--bg-raise)); border: 1px solid var(--line); border-radius: 14px; padding: 14px 16px; }
.pz-sum b { display: block; font-size: 26px; font-weight: 800; }
.pz-sum span { font-size: 12.5px; color: var(--muted); }
.pz-sum.red b { color: #f87171; } .pz-sum.yellow b { color: #fbbf24; } .pz-sum.green b { color: #34d399; }
.pz-map { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 12px; }
.pz-node { background: var(--card, var(--bg-raise)); border: 1.5px solid var(--line); border-radius: 14px; padding: 16px 14px; cursor: pointer; position: relative; transition: .15s; }
.pz-node:hover { transform: translateY(-2px); }
.pz-node .pn-st { position: absolute; top: 12px; right: 12px; width: 12px; height: 12px; border-radius: 50%; }
.pz-node .pn-name { font-size: 15px; font-weight: 700; padding-right: 18px; }
.pz-node .pn-act { font-size: 12px; margin-top: 8px; color: var(--muted); }
.pz-node.red { border-color: rgba(248,113,113,.5); } .pz-node.red .pn-st { background: #f87171; }
.pz-node.red .pn-act { color: #f87171; font-weight: 700; }
.pz-node.yellow { border-color: rgba(251,191,36,.5); } .pz-node.yellow .pn-st { background: #fbbf24; }
.pz-node.yellow .pn-act { color: #fbbf24; font-weight: 700; }
.pz-node.green { border-color: rgba(52,211,153,.5); } .pz-node.green .pn-st { background: #34d399; }
.pz-node.green .pn-act { color: #34d399; }
.pz-graph-actions { display: flex; gap: 12px; margin-top: 24px; flex-wrap: wrap; }
.pz-btn2 { padding: 11px 22px; border-radius: 12px; font-weight: 700; font-size: 14.5px; cursor: pointer; border: 1.5px solid var(--line); background: var(--card, var(--bg-raise)); color: var(--ink); }
.pz-btn2.primary { background: var(--brand); border-color: var(--brand); color: #fff; }
.pz-win { text-align: center; padding: 30px 16px; background: var(--card, var(--bg-raise)); border: 1px solid var(--line); border-radius: 18px; margin-top: 16px; }
.pz-win .pw-ic { font-size: 46px; }
.pz-win .pw-t { font-size: 20px; font-weight: 800; margin: 10px 0 6px; color: #34d399; }
.pz-win .pw-d { color: var(--muted); font-size: 14px; margin-bottom: 14px; }

@media (max-width: 560px) {
  .pz-title { font-size: 19px; }
  .pz-q { font-size: 17px; }
  .pz-units { grid-template-columns: 1fr; }
}

/* ===== 单元掌握进度条 ===== */
.pz-unit .pu-bar { height: 5px; border-radius: 3px; background: var(--bg-side, rgba(127,127,127,.18)); overflow: hidden; margin: 9px 0 5px; }
.pz-unit .pu-bar > i { display: block; height: 100%; border-radius: 3px; background: linear-gradient(90deg,#4338CA,#6D28D9); }

/* ===== 微讲解（红点先讲后练） ===== */
.pz-teach { background: var(--card, var(--bg-raise)); border: 1px solid var(--line); border-left: 3px solid var(--brand);
  border-radius: 14px; padding: 20px 22px; margin-bottom: 16px; }
.pz-teach .pt-tag { display: inline-block; font-size: 12px; font-weight: 700; color: var(--on-brand, var(--brand));
  background: rgba(124,109,255,.14); border-radius: 999px; padding: 4px 12px; margin-bottom: 12px; }
.pz-teach .pt-name { font-size: 19px; font-weight: 800; margin-bottom: 14px; }
.pz-teach .pt-t { font-size: 16px; font-weight: 700; margin-bottom: 8px; }
.pz-teach .pt-d { font-size: 14.5px; line-height: 1.9; color: var(--ink-2, var(--ink)); }
.pz-teach .pt-eg { margin-top: 14px; background: rgba(124,109,255,.10); border-radius: 10px;
  padding: 12px 14px; font-size: 14px; line-height: 1.7; }
.pz-teach .pt-eg b { display: block; font-size: 12.5px; color: var(--on-brand, var(--brand)); margin-bottom: 5px; }
.pz-teach .pt-key { margin-top: 14px; font-size: 13px; color: var(--muted); line-height: 1.7;
  border-top: 1px dashed var(--line); padding-top: 12px; }
.pz-teach .pt-pre { margin-top: 12px; font-size: 13px; line-height: 1.7; color: #fbbf24;
  background: rgba(251,191,36,.10); border-radius: 10px; padding: 10px 13px; }

/* ===== 错因提示 ===== */
.pz-why { margin-top: 6px; font-size: 13.5px; font-weight: 600; color: #fbbf24; }
.pz-node .pn-err { font-size: 11.5px; color: #f87171; margin-top: 7px; line-height: 1.5; }
.pz-foot { font-size: 12.5px; color: var(--muted); margin-top: 18px; line-height: 1.7; }

/* ===== 复测未通过态 / 结果按钮组 ===== */
.pz-win.no .pw-t { color: #fbbf24; }
.pz-win .pw-btns { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; margin-top: 6px; }

/* ============================================================
   数学排版（教材标准写法）—— 分数竖排
   供 AI 精准学（题干 / 选项 / 讲解 / 错因）与错题本共用。
   类名用 mathf 而非 frac：engine.css 里另有一套废弃的 .frac（无页面引入），
   取独立类名，避免将来引入 engine.css 时相互干扰。
   ============================================================ */
.mathf { display: inline-flex; flex-direction: column; align-items: center;
  justify-content: center; vertical-align: -0.42em; margin: 0 .16em;
  font-size: .88em; line-height: 1.06; font-weight: inherit;
  font-variant-numeric: tabular-nums; }
.mathf > i { font-style: normal; padding: 0 .26em; }
.mathf > b { font-weight: inherit; padding: 0 .26em; border-top: .12em solid currentColor; }
/* 含分数的行要留足行距，否则上下两行会贴在一起 */
.pz-q, .pt-d, .pt-eg, .pt-t, .pz-why { line-height: 1.78; }
/* 选项里的分数略缩，避免把选项卡片撑高；反馈行保持原大小，确保看清 */
.pz-opt .mathf { font-size: .92em; }
.pz-feed .mathf { font-size: 1em; vertical-align: -0.4em; }

/* ===== 周周清 / 月月清（遗忘回测） ===== */
/* 空状态（此前代码里用过 .pz-empty，但样式一直没定义 —— 这里补上） */
.pz-empty { text-align: center; color: var(--muted); font-size: 13.5px;
  padding: 26px 14px; line-height: 2; }
/* 选择页顶部的回测提醒卡片 */
.pz-revcard { background: linear-gradient(135deg, rgba(124,109,255,.16), rgba(124,109,255,.06));
  border: 1px solid rgba(124,109,255,.42); border-radius: 16px;
  padding: 14px 16px; margin: 0 0 20px; cursor: pointer; transition: .15s; position: relative; }
.pz-revcard:hover { transform: translateY(-2px); border-color: var(--brand); box-shadow: 0 8px 24px rgba(0,0,0,.22); }
.pz-revcard .pv-t { font-size: 15px; font-weight: 800; }
.pz-revcard .pv-d { font-size: 12.5px; color: var(--muted); margin-top: 5px; line-height: 1.85; }
.pz-revcard .pv-go { position: absolute; right: 16px; top: 50%; transform: translateY(-50%);
  font-size: 13px; font-weight: 700; color: var(--brand); }