:root{
  --green:#58cc02; --green-d:#46a302; --blue:#1cb0f6; --ink:#3c3c3c; --muted:#777;
  --line:#e5e7eb; --bg:#f7f9fb; --card:#fff; --radius:16px;
  --shadow:0 2px 0 var(--line),0 6px 20px rgba(0,0,0,.05);
}
*{box-sizing:border-box}
html,body{margin:0}
body{font-family:'Segoe UI',system-ui,-apple-system,sans-serif;color:var(--ink);background:var(--bg);
  display:flex;flex-direction:column;min-height:100vh}
.hidden{display:none !important}
.muted{color:var(--muted)}
.loader{padding:60px;text-align:center;color:var(--muted)}
button{font-family:inherit;cursor:pointer}

/* header */
header#topbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;gap:14px;
  padding:10px 18px;background:#fff;border-bottom:1px solid var(--line)}
.brand{font-size:22px;font-weight:800;color:var(--green);cursor:pointer;user-select:none}
.brand .sub{color:var(--blue)}
#hstats{flex:1;display:flex;gap:8px;justify-content:center}
.usermenu{display:flex;align-items:center;gap:10px}
.userchip{font-size:13px;color:var(--muted);max-width:200px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.pill{background:#fff;border:2px solid var(--line);border-radius:999px;padding:4px 12px;font-weight:700;font-size:14px}
.pill.streak{color:#ff9600;border-color:#ffe0b2}
.pill.xp{color:#febc2e;border-color:#ffe9b0}
.navbtn{border:2px solid var(--line);background:#fff;border-radius:12px;padding:8px 12px;font-weight:700;color:var(--ink)}
.navbtn:hover{background:#f2f5f8}
.navbtn.ghost{color:var(--muted)}
.navbtn.dl{text-decoration:none;display:inline-block;color:var(--green-d);border-color:#cdeeb5}

main#app{flex:1;width:100%;max-width:880px;margin:0 auto;padding:22px 16px}
footer#foot{text-align:center;color:var(--muted);font-size:12.5px;padding:18px;max-width:680px;margin:0 auto}

/* buttons */
.btn{background:var(--green);color:#fff;border:none;border-bottom:4px solid var(--green-d);
  border-radius:14px;padding:13px 22px;font-weight:800;font-size:15px;letter-spacing:.3px}
.btn:hover{filter:brightness(1.03)}
.btn:active{transform:translateY(2px);border-bottom-width:2px}
.btn.disabled{background:#e5e7eb;color:#aab;border-bottom-color:#d2d6db;pointer-events:none}
.btn.blue{background:var(--blue);border-bottom-color:#1799d6}
.btn.full{width:100%;margin-top:6px}

/* auth */
.authcard{max-width:380px;margin:40px auto;background:var(--card);border:1px solid var(--line);
  border-radius:var(--radius);box-shadow:var(--shadow);padding:28px}
.authbrand{font-size:28px;font-weight:800;color:var(--green);text-align:center}
.authsub{text-align:center;color:var(--muted);margin:6px 0 18px}
.authtabs{display:flex;gap:8px;margin-bottom:16px}
.atab{flex:1;border:2px solid var(--line);background:#fff;border-radius:12px;padding:10px;font-weight:700;color:var(--muted)}
.atab.on{border-color:var(--blue);color:var(--blue);background:#f1faff}
.field{margin-bottom:12px}
.field label{display:block;font-size:12px;font-weight:700;color:var(--muted);margin-bottom:5px}
.field input{width:100%;border:2px solid var(--line);border-radius:12px;padding:11px 12px;font-size:15px;outline:none}
.field input:focus{border-color:var(--blue)}
.autherr{color:#e03;font-size:13px;min-height:18px;margin:4px 0 8px}

/* course picker */
.coursewrap{padding-top:6px}
.h1{font-size:24px;margin:0 0 4px}
.coursegrid{display:flex;flex-direction:column;gap:14px;margin-top:18px}
.course{display:flex;gap:16px;align-items:center;background:var(--card);border:1px solid var(--line);
  border-radius:var(--radius);box-shadow:var(--shadow);padding:18px}
.cemoji{font-size:40px}
.cmain{flex:1}
.cmain h3{margin:0 0 6px;font-size:18px}
.cmain .muted{font-size:13px;line-height:1.45;margin:0 0 8px;
  display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}
.cmeta{font-size:12px;color:var(--muted)}
.cright{display:flex;flex-direction:column;align-items:center;gap:10px}
.ring{width:64px;height:64px}
.ring .ringbg{fill:none;stroke:#eef1f4;stroke-width:7}
.ring circle:not(.ringbg){fill:none;stroke-width:7;stroke-linecap:round;transition:stroke-dashoffset .6s}
.ring text{font-size:15px;font-weight:800;fill:var(--ink)}

/* toolbar (practice / map) */
.toolbar{display:flex;align-items:center;gap:10px;margin-bottom:14px;flex-wrap:wrap}
.ctitle{font-weight:800;font-size:16px}
.tbpills{flex:1;display:flex;gap:8px;justify-content:center}
.tbnav{display:flex;gap:8px}

/* progress bar */
.progresswrap{height:14px;background:#e9edf1;border-radius:999px;overflow:hidden;margin-bottom:16px}
#progressbar{height:100%;width:0;background:linear-gradient(90deg,var(--green),#7ed957);transition:width .5s}

/* lesson / exercise card */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:22px;animation:pop .25s ease}
@keyframes pop{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
.tag{display:inline-block;font-size:12px;font-weight:800;color:var(--blue);background:#eaf7ff;
  border-radius:999px;padding:4px 11px;margin-bottom:12px}
.tag.lesson{color:#7c4dff;background:#f0ebff}
.tag.review{color:#ff9600;background:#fff2df}
.card .title{margin:4px 0 10px;font-size:21px}
.body{line-height:1.6;font-size:15.5px}
.body p{margin:.6em 0}
.prompt{font-size:16px;line-height:1.55;margin-bottom:14px}
.actions{margin-top:18px}
.choices{display:flex;flex-direction:column;gap:10px}
.choice{text-align:left;border:2px solid var(--line);background:#fff;border-radius:14px;padding:13px 16px;font-size:15px}
.choice:hover{border-color:var(--blue);background:#f6fbff}
.choice.sel{border-color:var(--blue);background:#eaf7ff}
.choice.correct{border-color:var(--green);background:#eafce0}
.choice.wrong{border-color:#ff4b4b;background:#ffeceb}
.tfrow{display:flex;gap:12px}
.tf{flex:1;border:2px solid var(--line);background:#fff;border-radius:14px;padding:14px;font-weight:800;font-size:16px}
.tf.sel{border-color:var(--blue);background:#eaf7ff}
.num,.txt{width:100%;border:2px solid var(--line);border-radius:14px;padding:13px 15px;font-size:16px;outline:none}
.num:focus,.txt:focus{border-color:var(--blue)}
.feedback{margin-top:16px;border-radius:14px;padding:14px 16px;display:none}
.feedback.ok,.feedback.no{display:block}
.feedback.ok{background:#eafce0;border:1px solid #bfe9a3}
.feedback.no{background:#ffeceb;border:1px solid #f6b6b2}
.fh{font-weight:800;margin-bottom:6px}
.ex{font-size:14px;line-height:1.55}
.mline{margin-top:10px;font-size:13px;color:#555}
.mbar{height:8px;background:#e9edf1;border-radius:999px;overflow:hidden;margin-top:5px}
.mbar i{display:block;height:100%;background:var(--green)}
.card.done{text-align:center}.card.done .big{font-size:56px}

/* knowledge map */
.mapwrap{display:flex;flex-direction:column;gap:14px}
.graphbox{position:relative;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);overflow:hidden}
#graph{display:block;width:100%;cursor:grab;background:
  radial-gradient(circle at 50% 40%,#fbfdff,#eef3f7)}
.legend{position:absolute;left:12px;bottom:12px;display:flex;gap:12px;background:rgba(255,255,255,.85);
  border:1px solid var(--line);border-radius:10px;padding:7px 10px;font-size:12px}
.legend span{display:flex;align-items:center;gap:5px}
.legend i{width:11px;height:11px;border-radius:50%;display:inline-block}
.nodepanel{position:absolute;top:12px;right:12px;width:260px;max-height:calc(100% - 24px);overflow:auto;
  background:#fff;border:1px solid var(--line);border-radius:14px;box-shadow:0 8px 26px rgba(0,0,0,.12);padding:16px}
.nodepanel .x{position:absolute;top:8px;right:10px;border:none;background:none;font-size:20px;color:#999}
.nptag{display:inline-block;color:#fff;font-size:11px;font-weight:700;border-radius:999px;padding:3px 10px;margin-bottom:8px}
.nodepanel h3{margin:0 0 8px;font-size:16px}
.npmastery{font-size:13px;color:#555;margin-bottom:10px}
.nplbl{font-size:11px;font-weight:800;color:var(--muted);text-transform:uppercase;margin:10px 0 5px}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chip{font-size:12px;border:2px solid var(--line);border-radius:999px;padding:3px 9px;background:#fff}
.mapfoot{text-align:center;color:var(--muted);font-size:13px}

/* module breakdown grid */
.modgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:14px}
.modcard{background:var(--card);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow);padding:16px}
.modcard.locked{opacity:.7}
.modhead{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px}
.modhead h3{margin:0;font-size:15px;display:flex;align-items:center;gap:7px}
.moddot{width:11px;height:11px;border-radius:50%;display:inline-block}
.mp{font-weight:800;color:var(--muted);font-size:13px}
.cgrid{display:flex;flex-direction:column;gap:9px}
.concept .cn{display:flex;justify-content:space-between;font-size:13px}
.dot{font-size:12px}

/* global-map button on the course page */
.gmapbtn{margin:10px 0 4px;background:#f1faff;border-color:#bfe6ff;color:#1187c9}
.gmapbtn:hover{background:#e6f6ff}

/* create course / upload */
.courseactions{display:flex;gap:10px;flex-wrap:wrap;margin:10px 0 4px}
.createbtn{background:#eafce0;border-color:#bfe9a3;color:var(--green-d)}
.createbtn:hover{background:#e0f8d2}
.ownedtag{font-size:11px;font-weight:700;color:#7c4dff;background:#f0ebff;border-radius:999px;padding:2px 8px;margin-left:8px;vertical-align:middle}
.cdel{font-size:12px;padding:6px 10px;color:#c0392b}
input[type=file]{width:100%;border:2px dashed var(--line);border-radius:12px;padding:14px;background:#fafcfe;font-size:14px}
.upprogress{margin-top:18px}
.genbar{height:14px;background:#e9edf1;border-radius:999px;overflow:hidden}
.genbar i{display:block;height:100%;background:linear-gradient(90deg,var(--blue),#7ed957);transition:width .5s}
.genlabel{text-align:center;margin-top:8px;font-size:13px}
.gendone{text-align:center}
.gendone .big{font-size:48px}

/* settings / API keys */
.settingswrap{max-width:640px}
.keycard{margin-top:14px}
.keyhead{display:flex;justify-content:space-between;align-items:center;gap:10px}
.keyhead h3{margin:0;font-size:16px}
.keystatus{font-size:12px;font-weight:700;color:var(--muted);background:#f1f3f5;border-radius:999px;padding:4px 10px;white-space:nowrap}
.keystatus.on{color:var(--green-d);background:#eafce0}
.hint{font-size:12.5px;margin:6px 0 12px}
.keyrow{display:flex;gap:10px;flex-wrap:wrap}
.keyinput{flex:1;min-width:200px}
.keysave,.keydel{padding:11px 18px}
.keymsg{color:#e03;font-size:13px;min-height:16px;margin-top:8px}

/* placement exam */
.examintro{margin-bottom:14px}
.examintro h2{margin:0 0 6px;font-size:22px}
.examform{display:flex;flex-direction:column;gap:14px}
.examq .tag{color:#7c4dff;background:#f0ebff}
.examactions{margin-top:18px}

@media(max-width:640px){
  .course{flex-direction:column;text-align:center}
  .nodepanel{position:static;width:auto;max-height:none;margin-top:10px}
  #hstats{display:none}
}