:root{
  --bg:#f4f6fb;
  --card:#ffffff;
  --ink:#1f2937;
  --muted:#6b7280;
  --brand:#2563eb;
  --brand-dark:#1d4ed8;
  --brand-soft:#eff6ff;
  --ok:#16a34a;
  --ok-soft:#ecfdf5;
  --bad:#dc2626;
  --bad-soft:#fef2f2;
  --warn:#d97706;
  --line:#e5e7eb;
  --radius:14px;
  --shadow:0 2px 10px rgba(15,23,42,.06);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:var(--bg);
  color:var(--ink);
  font-family:"PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
  font-size:15px;
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none}
h1,h2,h3,h4{margin:0 0 .5em;line-height:1.4;font-weight:700}
p{margin:0 0 1em}
ul,ol{margin:0 0 1em;padding-left:1.4em}
code,.math{font-family:"Cambria Math","Times New Roman",serif;font-style:italic}

/* ---------- nav ---------- */
.nav{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.92);
  backdrop-filter:blur(8px);
  border-bottom:1px solid var(--line);
}
.nav-inner{
  max-width:1120px;margin:0 auto;padding:0 20px;height:60px;
  display:flex;align-items:center;gap:24px;
}
.logo{display:flex;align-items:center;gap:9px;font-weight:800;font-size:17px;color:var(--brand-dark);white-space:nowrap}
.logo .badge{
  width:30px;height:30px;border-radius:9px;background:var(--brand);color:#fff;
  display:flex;align-items:center;justify-content:center;font-size:15px;font-weight:700;
}
.nav-links{display:flex;gap:4px;margin-left:auto}
.nav-links a{
  padding:7px 14px;border-radius:9px;color:var(--muted);font-size:14.5px;font-weight:600;transition:.15s;
}
.nav-links a:hover{background:var(--brand-soft);color:var(--brand)}
.nav-links a.active{background:var(--brand);color:#fff}
@media(max-width:900px){
  .nav-inner{gap:8px;padding:0 10px}
  .nav-links{gap:0;margin-left:auto;flex:1;min-width:0;overflow-x:auto;scrollbar-width:none}
  .nav-links::-webkit-scrollbar{display:none}
  .nav-links a{padding:6px 8px;font-size:13px;white-space:nowrap}
  .logo span.txt{display:none}
}

/* ---------- layout ---------- */
.wrap{max-width:1120px;margin:0 auto;padding:24px 20px 60px}
.page-head{margin-bottom:20px}
.page-head h1{font-size:24px}
.page-head p{color:var(--muted);margin:0;font-size:14px}
.grid{display:grid;gap:16px}
.g2{grid-template-columns:repeat(2,1fr)}
.g3{grid-template-columns:repeat(3,1fr)}
.g4{grid-template-columns:repeat(4,1fr)}
@media(max-width:900px){.g3,.g4{grid-template-columns:repeat(2,1fr)}}
@media(max-width:620px){.g2,.g3{grid-template-columns:1fr}.g4{grid-template-columns:repeat(2,1fr)}}

.card{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:18px;box-shadow:var(--shadow);
}
.card h3{font-size:16px;margin-bottom:10px}
.muted{color:var(--muted);font-size:13.5px}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:6px;
  border:1px solid var(--line);background:#fff;color:var(--ink);
  padding:9px 18px;border-radius:10px;font-size:14.5px;font-weight:600;cursor:pointer;
  transition:.15s;font-family:inherit;
}
.btn:hover{border-color:var(--brand);color:var(--brand)}
.btn.primary{background:var(--brand);border-color:var(--brand);color:#fff}
.btn.primary:hover{background:var(--brand-dark);color:#fff}
.btn.ghost{background:var(--brand-soft);border-color:transparent;color:var(--brand)}
.btn:disabled{opacity:.45;cursor:not-allowed}
.btn-row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}

/* ---------- stat ---------- */
.stat{text-align:center}
.stat .num{font-size:28px;font-weight:800;color:var(--brand);line-height:1.2}
.stat .num.green{color:var(--ok)}
.stat .num.orange{color:var(--warn)}
.stat .label{font-size:13px;color:var(--muted)}

/* ---------- chips ---------- */
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip{
  padding:6px 14px;border:1px solid var(--line);border-radius:999px;background:#fff;
  font-size:13.5px;cursor:pointer;color:var(--muted);transition:.15s;user-select:none;
}
.chip:hover{border-color:var(--brand);color:var(--brand)}
.chip.on{background:var(--brand);border-color:var(--brand);color:#fff;font-weight:600}

/* ---------- progress bar ---------- */
.bar{height:8px;background:#eef2f7;border-radius:99px;overflow:hidden}
.bar > i{display:block;height:100%;background:var(--brand);border-radius:99px;transition:width .4s}
.bar.ok > i{background:var(--ok)}
.bar.warn > i{background:var(--warn)}

/* ---------- knowledge layout ---------- */
.kc{display:grid;grid-template-columns:230px 1fr;gap:18px;align-items:start}
@media(max-width:820px){.kc{grid-template-columns:1fr}}
.kc-side{position:sticky;top:80px}
@media(max-width:820px){.kc-side{position:static}}
.kc-side a{
  display:block;padding:9px 13px;border-radius:10px;font-size:14px;color:var(--muted);
  border-left:3px solid transparent;margin-bottom:2px;
}
.kc-side a:hover{background:var(--brand-soft);color:var(--brand)}
.kc-side a.on{background:var(--brand-soft);color:var(--brand-dark);border-left-color:var(--brand);font-weight:700}
.kc-body h2{font-size:20px;padding-bottom:10px;border-bottom:1px solid var(--line);margin-bottom:14px}

.point{
  background:var(--brand-soft);border-left:4px solid var(--brand);
  padding:10px 14px;border-radius:0 10px 10px 0;margin:10px 0;
}
.trap{
  background:#fff7ed;border-left:4px solid var(--warn);
  padding:10px 14px;border-radius:0 10px 10px 0;margin:10px 0;
}
.trap b{color:var(--warn)}
details.ex{border:1px solid var(--line);border-radius:12px;margin:10px 0;overflow:hidden}
details.ex > summary{
  padding:12px 16px;cursor:pointer;font-weight:600;background:#fafbfe;list-style:none;
}
details.ex > summary::-webkit-details-marker{display:none}
details.ex > summary::before{content:"▸ ";color:var(--brand)}
details.ex[open] > summary::before{content:"▾ "}
details.ex .body{padding:4px 16px 14px;border-top:1px solid var(--line);background:#fff}

/* ---------- quiz ---------- */
.q-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.q-meta{display:flex;gap:10px;align-items:center;margin-bottom:12px;flex-wrap:wrap}
.tag{font-size:12px;padding:3px 10px;border-radius:6px;background:#eef2f7;color:var(--muted);font-weight:600}
.tag.topic{background:var(--brand-soft);color:var(--brand)}
.q-stem{font-size:16.5px;font-weight:600;margin-bottom:14px}
.opts{display:grid;gap:10px}
.opt{
  display:flex;gap:10px;align-items:flex-start;padding:11px 14px;border:1px solid var(--line);
  border-radius:11px;cursor:pointer;transition:.15s;background:#fff;
}
.opt:hover{border-color:var(--brand);background:#fbfdff}
.opt .k{
  width:24px;height:24px;flex:0 0 24px;border-radius:50%;background:#eef2f7;color:var(--muted);
  display:flex;align-items:center;justify-content:center;font-size:13px;font-weight:700;
}
.opt.sel{border-color:var(--brand);background:var(--brand-soft)}
.opt.sel .k{background:var(--brand);color:#fff}
.opt.right{border-color:var(--ok);background:var(--ok-soft)}
.opt.right .k{background:var(--ok);color:#fff}
.opt.wrong{border-color:var(--bad);background:var(--bad-soft)}
.opt.wrong .k{background:var(--bad);color:#fff}
.fill-in{
  width:220px;padding:10px 14px;border:1px solid var(--line);border-radius:10px;font-size:16px;
  font-family:inherit;outline:none;
}
.fill-in:focus{border-color:var(--brand)}
.fb{margin-top:16px;padding:14px 16px;border-radius:12px;border:1px solid var(--line);background:#fafbfe}
.fb.ok{background:var(--ok-soft);border-color:#a7f3d0}
.fb.no{background:var(--bad-soft);border-color:#fecaca}
.fb .verdict{font-weight:800;margin-bottom:6px}
.fb.ok .verdict{color:var(--ok)}
.fb.no .verdict{color:var(--bad)}
.fb .sol{white-space:pre-wrap}
.ans-line{font-weight:700}

/* ---------- result ---------- */
.res-hero{text-align:center;padding:20px 0}
.res-hero .big{font-size:46px;font-weight:800;color:var(--brand);line-height:1.1}
.res-hero .big.green{color:var(--ok)}
.res-hero .big.orange{color:var(--warn)}

/* ---------- formula ---------- */
.f-group{margin-bottom:8px}
.f-item{
  border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin-bottom:10px;background:#fff;
}
.f-item .fx{font-size:17px;font-family:"Cambria Math",serif;font-style:italic;color:var(--brand-dark);font-weight:600}
.f-item .note{font-size:13.5px;color:var(--muted);margin-top:4px}
.search{
  width:100%;padding:11px 16px;border:1px solid var(--line);border-radius:11px;font-size:15px;
  outline:none;font-family:inherit;margin-bottom:16px;
}
.search:focus{border-color:var(--brand)}

/* ---------- graph lab ---------- */
.lab{display:grid;grid-template-columns:1fr 260px;gap:16px;align-items:start}
@media(max-width:820px){.lab{grid-template-columns:1fr}}
.slider-row{margin-bottom:12px}
.slider-row label{display:flex;justify-content:space-between;font-size:14px;font-weight:600;margin-bottom:4px}
.slider-row label b{color:var(--brand);font-variant-numeric:tabular-nums}
input[type=range]{width:100%;accent-color:var(--brand)}
.lab-info{background:#fafbfe;border:1px solid var(--line);border-radius:12px;padding:12px 14px;font-size:14px}
.lab-info div{display:flex;justify-content:space-between;padding:3px 0}
.lab-info div span:last-child{font-weight:700;font-variant-numeric:tabular-nums}
canvas{width:100%;max-width:640px;background:#fff;border:1px solid var(--line);border-radius:12px;display:block;margin:0 auto}
#grid{max-width:560px}

/* ---------- 题卡 ---------- */
.cards{display:flex;flex-wrap:wrap;gap:6px}
.cards .cell{
  width:32px;height:32px;border:1px solid var(--line);border-radius:8px;background:#fff;
  display:flex;align-items:center;justify-content:center;font-size:13px;color:var(--muted);
  cursor:pointer;transition:.15s;user-select:none;
}
.cards .cell:hover{border-color:var(--brand);color:var(--brand)}
.cards .cell.on{background:var(--brand-soft);border-color:#bfdbfe;color:var(--brand-dark);font-weight:700}
.cards .cell.cur{background:var(--brand);border-color:var(--brand);color:#fff;font-weight:800}

/* ---------- 模型库 ---------- */
.model{
  border:1px solid var(--line);border-radius:12px;background:#fff;overflow:hidden;margin-bottom:12px;
}
.model > summary{
  padding:13px 16px;cursor:pointer;list-style:none;display:flex;align-items:center;gap:10px;
  background:#fafbfe;font-weight:700;
}
.model > summary::-webkit-details-marker{display:none}
.model > summary .st{font-weight:400;color:var(--muted);font-size:13.5px}
.model > summary::before{content:"▸ ";color:var(--brand)}
.model[open] > summary::before{content:"▾ "}
.model .body{padding:14px 16px;border-top:1px solid var(--line)}
.model .body .d{white-space:pre-wrap;margin-bottom:10px}
.model .tip{
  background:#fff7ed;border-left:4px solid var(--warn);padding:8px 12px;border-radius:0 8px 8px 0;font-size:14px;
}
.cat-title{display:flex;align-items:center;gap:10px;margin:22px 0 10px}
.cat-title .dot{width:10px;height:10px;border-radius:50%}

/* ---------- 学习计划 ---------- */
.plan-progress{
  display:flex;align-items:center;gap:14px;background:#fff;border:1px solid var(--line);
  border-radius:var(--radius);padding:16px 18px;margin-bottom:18px;box-shadow:var(--shadow);
}
.plan-progress .bar{flex:1}
.task{
  display:flex;gap:11px;align-items:flex-start;padding:9px 0;border-bottom:1px dashed var(--line);
}
.task:last-child{border-bottom:none}
.task input{width:18px;height:18px;margin-top:3px;accent-color:var(--brand);cursor:pointer;flex:0 0 18px}
.task label{cursor:pointer;font-size:14.5px}
.task.done label{color:var(--muted);text-decoration:line-through}

/* ---------- wrong book ---------- */
.wrong-item{border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin-bottom:12px;background:#fff}
.empty{text-align:center;padding:50px 20px;color:var(--muted)}
.empty .ico{font-size:44px;margin-bottom:8px}

.footer{text-align:center;color:var(--muted);font-size:13px;padding:30px 0 10px}
.hide{display:none !important}

/* ---------- 首页今日复习提示 ---------- */
.callout{
  display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;
  background:linear-gradient(135deg,#eff6ff,#f5f3ff);
  border:1px solid #dbeafe;border-radius:12px;padding:12px 14px;margin-top:14px;
}

/* ---------- 错题本 · 复习排期 ---------- */
.review-panel{margin-bottom:14px}
.review-nums{display:flex;gap:30px;margin-bottom:10px;flex-wrap:wrap}
.review-nums .n{font-size:26px;font-weight:800;color:var(--brand);line-height:1.2}
.review-nums .n.warn{color:var(--warn)}
.review-nums .n.ok{color:var(--ok)}
.dots{display:inline-flex;gap:3px;align-items:center;padding:0 2px}
.dots i{width:6px;height:6px;border-radius:50%;background:#e5e7eb;display:block}
.dots i.on{background:var(--brand)}
.wrong-item.due{border-color:#fde68a;background:#fffdf5}
.tag-warn{background:#fef3c7;color:#b45309}

/* ---------- 公式自测 ---------- */
.f-item.mask .fx{
  color:transparent;background:#eef2f7;border-radius:6px;cursor:pointer;
  user-select:none;position:relative;
}
.f-item.mask .fx::after{
  content:"点击核对公式";position:absolute;left:10px;top:0;
  color:#94a3b8;font-family:inherit;font-style:normal;font-size:13px;font-weight:400;
}
.f-item.mask:hover .fx{background:#e0e7ff}

/* ---------- 学习报告 ---------- */
.countdown{display:flex;align-items:center;gap:22px;flex-wrap:wrap}
.cd-main{display:flex;align-items:baseline;gap:6px}
.cd-num{font-size:56px;font-weight:800;color:var(--brand);line-height:1;font-variant-numeric:tabular-nums}
.cd-unit{font-size:16px;color:var(--muted);font-weight:600}
.cd-text{flex:1;min-width:220px}
.cd-set{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.cd-set input{
  padding:8px 10px;border:1px solid var(--line);border-radius:9px;
  font-family:inherit;font-size:14px;color:var(--ink);background:#fff;outline:none;
}
.cd-set input:focus{border-color:var(--brand)}
.cv-wrap{width:100%}
.cv-wrap.narrow{max-width:420px;margin:0 auto}
.chart-legend{display:flex;gap:16px;flex-wrap:wrap;margin-top:10px;font-size:12.5px;color:var(--muted)}
.chart-legend span{display:inline-flex;align-items:center;gap:6px}
.chart-legend i{width:10px;height:10px;border-radius:3px;display:inline-block}
.action-item{display:flex;align-items:center;gap:14px;padding:13px 0;border-bottom:1px dashed var(--line)}
.action-item:last-child{border-bottom:none;padding-bottom:0}
.action-item .ai-main{flex:1}
.action-item .muted{margin-top:2px}

@media(max-width:620px){
  .cd-num{font-size:42px}
  .review-nums{gap:18px}
  .action-item{align-items:flex-start;flex-direction:column;gap:8px}
  .action-item .btn{width:100%}
}

/* ---------- 错题照片 ---------- */
.photo-slot{margin-top:10px;display:flex;align-items:flex-start;gap:10px;flex-wrap:wrap}
.photo-slot:empty{display:none}
.photo-link{display:inline-block;line-height:0}
.photo-slot img{
  max-width:170px;max-height:130px;border-radius:10px;
  border:1px solid var(--line);cursor:zoom-in;display:block;
}

/* ---------- AI 讲题 ---------- */
.ai-form{display:grid;gap:10px;max-width:520px}
.ai-form label{display:grid;gap:4px;font-size:13px;font-weight:600;color:#374151}
.ai-form input{
  padding:9px 12px;border:1px solid var(--line);border-radius:9px;
  font-family:inherit;font-size:14px;outline:none;background:#fff;color:var(--ink);
}
.ai-form input:focus{border-color:var(--brand)}
.ai-box{
  margin-top:12px;border:1px solid #dbeafe;background:#f8fbff;
  border-radius:12px;padding:12px 14px;font-size:14px;line-height:1.75;
}
.ai-box.bad{border-color:#fecaca;background:var(--bad-soft)}
.ai-box .ai-head{font-weight:700;color:var(--brand-dark);margin-bottom:6px}
.ai-box.bad .ai-head{color:var(--bad)}
.ai-loading{color:var(--muted);font-size:14px}
.ai-text{white-space:normal;word-break:break-word}

/* ---------- 同步码 ---------- */
#code-text{
  width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:10px;
  font-family:Consolas,Monaco,monospace;font-size:12px;line-height:1.5;
  resize:vertical;outline:none;background:#fafbfe;color:var(--ink);
}
#code-text:focus{border-color:var(--brand)}

/* ---------- 指令行走 ---------- */
#code{
  width:100%;padding:12px 14px;border:1px solid var(--line);border-radius:11px;
  font-family:Consolas,Monaco,monospace;font-size:14px;line-height:1.7;
  resize:vertical;outline:none;background:#fafbfe;color:var(--ink);
}
#code:focus{border-color:var(--brand);background:#fff}
.state-row{display:flex;justify-content:space-between;gap:10px;padding:7px 0;border-bottom:1px dashed var(--line);font-size:14px}
.state-row:last-child{border-bottom:none}
.math-note{margin-top:14px;background:var(--brand-soft);border-radius:12px;padding:12px 14px;font-size:13.5px;line-height:1.9}
.math-note .mono{font-family:Consolas,Monaco,monospace;font-size:13px;margin-top:4px}
.msg{margin-top:10px;font-size:13.5px;color:var(--ok);min-height:20px}
.msg.bad{color:var(--bad)}
.walk-grid{align-items:start}