/* ============ THEME ============ */
:root{
  --bg:#f4f3ef; --surface:#ffffff; --surface2:#faf9f6; --ink:#1e222c; --ink2:#5d6475;
  --line:#e7e4dc; --line2:#d9d5cb; --accent:#4f46e5;
  --a:#c2740a; --b:#2563eb; --c:#059669; --d:#7c3aed; --e:#dc2626;
  --a-bg:#fff8ec; --b-bg:#eff5ff; --c-bg:#ecfdf5; --d-bg:#f6f1ff; --e-bg:#fef2f2;
  --code-bg:#0f172a; --code-head:#1e293b; --code-ink:#e2e8f0;
  --kw:#c792ea; --str:#c3e88d; --com:#64748b; --num:#f78c6c; --fn:#ffcb6b; --bi:#82aaff;
  --shadow:0 1px 2px rgba(16,20,32,.05), 0 8px 24px -12px rgba(16,20,32,.16);
}
[data-theme="dark"]{
  --bg:#0e1015; --surface:#161a22; --surface2:#1a1f29; --ink:#e8eaf0; --ink2:#9aa3b5;
  --line:#262c38; --line2:#333b4a; --accent:#818cf8;
  --a:#fbbf24; --b:#60a5fa; --c:#34d399; --d:#a78bfa; --e:#f87171;
  --a-bg:#231c0c; --b-bg:#101b30; --c-bg:#0c2019; --d-bg:#1a1430; --e-bg:#2a1213;
  --code-bg:#0a0d14; --code-head:#151a24; --code-ink:#e2e8f0;
  --shadow:0 1px 2px rgba(0,0,0,.4), 0 8px 24px -12px rgba(0,0,0,.6);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0; background:var(--bg); color:var(--ink);
  font:16.5px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",Inter,Roboto,Helvetica,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;
}
code,kbd,pre{font-family:ui-monospace,SFMono-Regular,"JetBrains Mono",Menlo,Consolas,monospace}
a{color:var(--accent); text-decoration:none}
a:hover{text-decoration:underline}

/* ============ SIDEBAR ============ */
.sidebar{
  position:fixed; inset:0 auto 0 0; width:284px; background:var(--surface);
  border-right:1px solid var(--line); padding:20px 16px; overflow-y:auto; z-index:50;
  display:flex; flex-direction:column; gap:16px;
}
.brand{display:flex; gap:11px; align-items:center}
.logo{
  width:40px; height:40px; border-radius:11px; flex:none;
  background:linear-gradient(135deg,#4f46e5,#8b5cf6); color:#fff;
  display:grid; place-items:center; font-weight:800; font-size:15px; letter-spacing:.5px;
}
.brand strong{display:block; font-size:15.5px; letter-spacing:-.2px}
.brand span{display:block; font-size:11.5px; color:var(--ink2)}
.progress-card{background:var(--surface2); border:1px solid var(--line); border-radius:12px; padding:11px 12px}
.progress-label{display:flex; justify-content:space-between; font-size:11.5px; color:var(--ink2); font-weight:600; text-transform:uppercase; letter-spacing:.6px}
.bar{height:7px; background:var(--line); border-radius:99px; margin:8px 0 7px; overflow:hidden}
.bar>i{display:block; height:100%; width:0%; border-radius:99px; background:linear-gradient(90deg,#4f46e5,#8b5cf6); transition:width .35s ease}
.mini{font-size:11.5px; color:var(--ink2); background:none; border:0; padding:0; cursor:pointer}
.mini:hover{color:var(--e); text-decoration:underline}
nav{display:flex; flex-direction:column; gap:2px}
.nav-track{
  font-size:10.5px; font-weight:800; letter-spacing:1.1px; text-transform:uppercase;
  color:var(--ink2); margin:14px 6px 5px; display:flex; align-items:center; gap:7px;
}
.nav-track::after{content:""; flex:1; height:1px; background:var(--line)}
.nav-track b{width:8px; height:8px; border-radius:3px; display:inline-block}
.nav-item{
  display:flex; align-items:baseline; gap:9px; padding:6px 9px; border-radius:8px;
  color:var(--ink2); font-size:13.4px; line-height:1.35;
}
.nav-item i{font-style:normal; font-size:10.5px; font-weight:700; opacity:.65; font-variant-numeric:tabular-nums}
.nav-item:hover{background:var(--surface2); color:var(--ink); text-decoration:none}
.nav-item.active{background:var(--surface2); color:var(--ink); font-weight:650; box-shadow:inset 2.5px 0 0 var(--accent)}
.nav-item.done i::after{content:" ✓"; color:var(--c); font-weight:800}
.side-foot{margin-top:auto; display:flex; gap:8px; align-items:center; padding-top:8px; border-top:1px solid var(--line)}
.icon-btn{
  border:1px solid var(--line2); background:var(--surface2); color:var(--ink2);
  border-radius:9px; padding:6px 10px; font-size:13px; cursor:pointer;
}
.icon-btn:hover{color:var(--ink); border-color:var(--ink2)}
.sidebar-toggle{display:none}

/* ============ MAIN ============ */
main{margin-left:284px; padding:34px 34px 90px}
.wrap{max-width:910px; margin:0 auto}
.hero{margin-bottom:30px}
.eyebrow{font-size:12px; font-weight:800; letter-spacing:1.6px; text-transform:uppercase; color:var(--accent)}
.hero h1{font-size:40px; line-height:1.12; letter-spacing:-1.2px; margin:8px 0 10px}
.hero p.lead{font-size:18px; color:var(--ink2); margin:0 0 18px; max-width:70ch}
.howto{display:grid; grid-template-columns:repeat(3,1fr); gap:12px; margin-top:18px}
.howto div{background:var(--surface); border:1px solid var(--line); border-radius:13px; padding:14px 15px; box-shadow:var(--shadow)}
.howto b{display:block; font-size:13.5px; margin-bottom:3px}
.howto span{font-size:13.2px; color:var(--ink2)}
.trackmap{display:grid; gap:9px; margin-top:18px}
.track-row{
  display:flex; gap:13px; align-items:flex-start; background:var(--surface);
  border:1px solid var(--line); border-left:4px solid var(--tc); border-radius:11px; padding:12px 15px;
}
.track-row b{font-size:14px}
.track-row p{margin:2px 0 0; font-size:13.4px; color:var(--ink2)}
.track-row .tnum{
  flex:none; width:26px; height:26px; border-radius:8px; background:var(--tc-bg); color:var(--tc);
  display:grid; place-items:center; font-weight:800; font-size:12.5px;
}

/* ============ MODULE CARD ============ */
.module{
  background:var(--surface); border:1px solid var(--line); border-radius:16px;
  padding:28px 32px 30px; margin-bottom:26px; box-shadow:var(--shadow);
  scroll-margin-top:18px; position:relative;
}
.module::before{
  content:""; position:absolute; left:0; top:22px; bottom:22px; width:4px;
  border-radius:0 4px 4px 0; background:var(--tc,var(--accent));
}
.mod-head{display:flex; align-items:flex-start; gap:14px; flex-wrap:wrap}
.mod-head h2{font-size:25px; letter-spacing:-.6px; margin:0; flex:1; min-width:240px}
.badge{
  font-size:10.5px; font-weight:800; letter-spacing:.9px; text-transform:uppercase;
  background:var(--tc-bg); color:var(--tc); padding:4px 9px; border-radius:99px;
}
.meta{display:flex; gap:14px; flex-wrap:wrap; font-size:12.5px; color:var(--ink2); margin:7px 0 0}
.done-toggle{
  display:flex; align-items:center; gap:7px; font-size:12.5px; font-weight:650; color:var(--ink2);
  border:1px solid var(--line2); background:var(--surface2); padding:6px 11px; border-radius:99px;
  cursor:pointer; user-select:none; white-space:nowrap;
}
.done-toggle:hover{border-color:var(--c); color:var(--c)}
.done-toggle.on{background:var(--c-bg); border-color:var(--c); color:var(--c)}
.module h3{
  font-size:17.5px; letter-spacing:-.3px; margin:26px 0 8px;
  padding-left:11px; border-left:3px solid var(--tc,var(--accent));
}
.module h4{font-size:15px; margin:18px 0 6px}
.module p{margin:9px 0}
.module ul,.module ol{margin:9px 0; padding-left:22px}
.module li{margin:5px 0}
.module li::marker{color:var(--tc,var(--accent)); font-weight:700}
strong{font-weight:680}
.lead-in{font-size:17px; color:var(--ink2); margin-top:14px !important}
code:not(pre code){
  background:var(--surface2); border:1px solid var(--line); border-radius:5px;
  padding:1px 5px; font-size:.87em; color:var(--accent);
}

/* boxes */
.goals{
  background:var(--surface2); border:1px solid var(--line); border-radius:12px;
  padding:14px 17px; margin-top:16px;
}
.goals h4{margin:0 0 6px; font-size:13px; letter-spacing:.8px; text-transform:uppercase; color:var(--ink2)}
.goals ul{margin:0 !important}
.callout{
  border-radius:11px; padding:13px 16px; margin:16px 0; font-size:15.2px;
  border:1px solid; border-left-width:4px;
}
.callout b.tag{display:block; font-size:11.5px; letter-spacing:.9px; text-transform:uppercase; margin-bottom:3px; opacity:.85}
.callout p{margin:5px 0}
.callout p:last-child{margin-bottom:0}
.tip{background:var(--b-bg); border-color:var(--b); color:var(--ink)}
.tip b.tag{color:var(--b)}
.pitfall{background:var(--e-bg); border-color:var(--e)}
.pitfall b.tag{color:var(--e)}
.remember{background:var(--a-bg); border-color:var(--a)}
.remember b.tag{color:var(--a)}
.prod{background:var(--d-bg); border-color:var(--d)}
.prod b.tag{color:var(--d)}
.exercise{
  background:var(--surface2); border:2px dashed var(--line2); border-radius:12px;
  padding:15px 18px; margin:18px 0 6px;
}
.exercise b.tag{display:block; font-size:11.5px; letter-spacing:.9px; text-transform:uppercase; color:var(--c); margin-bottom:4px}
.exercise ul{margin-bottom:0}

/* formula */
.formula{
  background:var(--surface2); border:1px solid var(--line); border-radius:11px;
  padding:13px 16px; margin:14px 0; text-align:center;
  font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace; font-size:15.2px;
  overflow-x:auto; letter-spacing:.2px;
}
.formula .note{display:block; font-family:inherit; font-size:12.5px; color:var(--ink2); margin-top:6px; letter-spacing:0}

/* code */
.code-block{margin:16px 0; border-radius:11px; overflow:hidden; border:1px solid #0b1220; box-shadow:var(--shadow)}
.code-bar{
  background:var(--code-head); color:#94a3b8; font-size:11.5px; font-weight:700;
  letter-spacing:.8px; text-transform:uppercase; padding:7px 13px;
  display:flex; justify-content:space-between; align-items:center;
}
.code-bar button{
  background:rgba(255,255,255,.07); border:1px solid rgba(255,255,255,.13); color:#cbd5e1;
  border-radius:6px; font-size:11px; padding:3px 9px; cursor:pointer; letter-spacing:.4px;
}
.code-bar button:hover{background:rgba(255,255,255,.16); color:#fff}
.code-block pre{
  margin:0; background:var(--code-bg); color:var(--code-ink); padding:15px 17px;
  overflow-x:auto; font-size:13.4px; line-height:1.62; tab-size:4;
}
.code-block .k{color:var(--kw)} .code-block .s{color:var(--str)}
.code-block .c{color:var(--com); font-style:italic} .code-block .n{color:var(--num)}
.code-block .f{color:var(--fn)} .code-block .b{color:var(--bi)}

/* tables */
.tablewrap{overflow-x:auto; margin:16px 0; border:1px solid var(--line); border-radius:11px}
table{border-collapse:collapse; width:100%; font-size:14.3px; background:var(--surface)}
th,td{padding:9px 13px; text-align:left; border-bottom:1px solid var(--line); vertical-align:top}
th{background:var(--surface2); font-size:12px; letter-spacing:.6px; text-transform:uppercase; color:var(--ink2)}
tr:last-child td{border-bottom:0}
tbody tr:hover{background:var(--surface2)}

/* flow chips */
.flow{display:flex; flex-wrap:wrap; gap:7px; align-items:center; margin:14px 0}
.chip{
  background:var(--surface2); border:1px solid var(--line2); border-radius:9px;
  padding:7px 12px; font-size:13.4px; font-weight:600;
}
.chip small{display:block; font-weight:400; font-size:11.6px; color:var(--ink2)}
.arrow{color:var(--ink2); font-size:13px}

/* steps */
.steps{counter-reset:s; list-style:none; padding:0 !important; margin:14px 0}
.steps li{counter-increment:s; position:relative; padding:0 0 12px 38px; margin:0}
.steps li::before{
  content:counter(s); position:absolute; left:0; top:1px; width:25px; height:25px;
  background:var(--tc-bg,var(--surface2)); color:var(--tc,var(--accent)); border:1px solid var(--line2);
  border-radius:50%; display:grid; place-items:center; font-size:12.5px; font-weight:800;
}
.steps li::after{content:""; position:absolute; left:12.5px; top:28px; bottom:2px; width:1.5px; background:var(--line)}
.steps li:last-child::after{display:none}

/* recall flashcards */
details.recall{
  background:var(--surface2); border:1px solid var(--line); border-radius:11px;
  padding:0; margin:9px 0; overflow:hidden;
}
details.recall summary{
  cursor:pointer; padding:12px 16px; font-weight:640; font-size:14.6px; list-style:none;
  display:flex; gap:10px; align-items:flex-start;
}
details.recall summary::-webkit-details-marker{display:none}
details.recall summary::before{
  content:"↺ recall"; flex:none; font-size:10px; font-weight:800; letter-spacing:.7px;
  text-transform:uppercase; color:var(--tc,var(--accent)); background:var(--surface);
  border:1px solid var(--line2); border-radius:99px; padding:2px 8px; margin-top:2px;
}
details.recall[open] summary::before{content:"✓ answered"; color:var(--c)}
details.recall summary:hover{background:var(--surface)}
details.recall .ans{
  padding:0 16px 14px 16px; font-size:14.6px; color:var(--ink2); border-top:1px dashed var(--line2);
  padding-top:11px; margin-top:0;
}
details.recall .ans strong{color:var(--ink)}

/* quiz */
.quiz{background:var(--surface2); border:1px solid var(--line); border-radius:12px; padding:6px 18px 14px; margin-top:14px}
.quiz ol{padding-left:22px}
.quiz li{margin:9px 0}

/* checklist */
.checklist{list-style:none; padding:0 !important}
.checklist li{
  background:var(--surface2); border:1px solid var(--line); border-radius:9px;
  padding:9px 13px 9px 40px; position:relative; margin:7px 0;
}
.checklist li::before{
  content:""; position:absolute; left:13px; top:12px; width:15px; height:15px;
  border:1.8px solid var(--line2); border-radius:4.5px; background:var(--surface);
}
.kicker{font-size:13px; color:var(--ink2); font-style:italic}
hr.sep{border:0; border-top:1px solid var(--line); margin:24px 0}

/* ============ RESPONSIVE ============ */
@media (max-width:960px){
  .sidebar{transform:translateX(-100%); transition:transform .28s ease; box-shadow:0 0 60px rgba(0,0,0,.25)}
  .sidebar.open{transform:none}
  main{margin-left:0; padding:20px 16px 70px}
  .module{padding:22px 18px 24px}
  .hero h1{font-size:30px}
  .howto{grid-template-columns:1fr}
  .sidebar-toggle{
    display:grid; place-items:center; position:fixed; left:14px; top:14px; z-index:60;
    width:44px; height:44px; border-radius:12px; border:1px solid var(--line2);
    background:var(--surface); color:var(--ink); font-size:18px; box-shadow:var(--shadow); cursor:pointer;
  }
  main{padding-top:74px}
}
@media print{
  .sidebar,.sidebar-toggle{display:none}
  main{margin:0; padding:0}
  .module{box-shadow:none; break-inside:avoid; border-color:#ccc}
  .done-toggle,.code-bar button{display:none}
}