:root{
  --navy:#243f66;
  --navy2:#31537f;
  --red:#b53333;
  --text:#26364a;
  --muted:#6c7887;
  --line:#e2e7ee;
  --soft:#f6f8fb;
  --soft2:#eef3f8;
  --success:#2f6b55;
  --warning:#926d20;
  --danger:#9d3636;
  --white:#fff;
  --shadow:0 12px 34px rgba(31,52,82,.10);
  --radius:18px;
}
*{box-sizing:border-box}
html,body{margin:0;min-height:100%;font-family:Inter,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;color:var(--text);background:#f4f6f9}
button,input{font:inherit}
button{cursor:pointer}
.app-shell{min-height:100vh}
.topbar{height:72px;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 28px;position:sticky;top:0;z-index:5}
.brand{display:flex;align-items:center;gap:12px;color:var(--navy);font-weight:700}
.brand-mark{width:34px;height:34px;border-radius:50%;background:var(--navy);position:relative;box-shadow:inset 0 0 0 6px #fff;border:2px solid var(--navy)}
.brand-mark:after{content:"";position:absolute;width:8px;height:8px;border-radius:50%;background:var(--red);right:-3px;top:-3px;border:2px solid #fff}
.brand-copy small{display:block;font-size:11px;letter-spacing:.13em;text-transform:uppercase;color:var(--muted);font-weight:600;margin-top:2px}
.top-actions{display:flex;gap:10px;align-items:center}.student-name{font-size:14px;color:var(--muted)}
.page{max-width:1180px;margin:0 auto;padding:34px 24px 64px}
.hero{background:linear-gradient(135deg,var(--navy),var(--navy2));color:#fff;border-radius:24px;padding:32px;box-shadow:var(--shadow);display:flex;justify-content:space-between;gap:20px;align-items:center}
.hero h1{font-family:"Libre Baskerville",serif;margin:0 0 8px;font-size:34px}.hero p{margin:0;color:#dfe8f3}.hero-badge{background:rgba(255,255,255,.13);padding:12px 15px;border:1px solid rgba(255,255,255,.2);border-radius:14px;white-space:nowrap}
.section-title{margin:30px 0 14px;display:flex;justify-content:space-between;align-items:end}.section-title h2{margin:0;color:var(--navy);font-size:22px}.section-title p{margin:4px 0 0;color:var(--muted);font-size:14px}
.card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);box-shadow:0 4px 16px rgba(40,60,85,.04)}
.assignment-card{padding:22px;display:grid;grid-template-columns:1fr auto;gap:18px;align-items:center}.assignment-card h3{margin:0 0 6px;color:var(--navy)}.assignment-meta{display:flex;gap:14px;flex-wrap:wrap;color:var(--muted);font-size:13px}.pill{display:inline-flex;align-items:center;border-radius:999px;padding:6px 10px;background:var(--soft2);color:var(--navy);font-size:12px;font-weight:600}
.btn{border:0;border-radius:12px;padding:11px 16px;font-weight:700;background:var(--navy);color:#fff;box-shadow:none}.btn:hover{filter:brightness(1.04)}.btn.secondary{background:#fff;color:var(--navy);border:1px solid var(--line)}.btn.ghost{background:transparent;color:var(--navy);border:1px solid transparent}.btn.red{background:var(--red)}.btn.small{padding:8px 12px;font-size:13px}.btn:disabled{opacity:.55;cursor:not-allowed}
.login-wrap{min-height:100vh;display:grid;grid-template-columns:1.1fr .9fr;background:#fff}.login-art{background:linear-gradient(145deg,var(--navy),#172b49);padding:60px;color:white;display:flex;flex-direction:column;justify-content:space-between}.login-art h1{font-family:"Libre Baskerville",serif;font-size:46px;line-height:1.08;margin:0;max-width:650px}.login-art p{max-width:560px;color:#dfe8f3;font-size:17px;line-height:1.6}.login-panel{display:flex;align-items:center;justify-content:center;padding:40px}.login-card{width:100%;max-width:420px}.login-card h2{font-size:28px;color:var(--navy);margin:0 0 8px}.login-card .sub{color:var(--muted);margin-bottom:28px}.field{margin-bottom:16px}.field label{display:block;font-size:13px;font-weight:700;margin-bottom:7px;color:var(--navy)}.field input{width:100%;border:1px solid var(--line);border-radius:12px;padding:13px 14px;outline:none}.field input:focus{border-color:var(--navy2);box-shadow:0 0 0 3px rgba(49,83,127,.10)}.login-card .btn{width:100%;margin-top:4px;padding:13px}.error{margin-top:14px;padding:12px 14px;border-radius:12px;background:#fff0f0;color:var(--danger);font-size:13px;border:1px solid #f2caca}.tiny{font-size:12px;color:var(--muted)}
.assignment-shell{display:grid;grid-template-columns:260px 1fr;gap:22px;align-items:start}.sidebar{position:sticky;top:92px;padding:18px}.progress-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px}.progress-bar{height:8px;background:var(--soft2);border-radius:999px;overflow:hidden}.progress-fill{height:100%;background:var(--navy);transition:.2s}.navigator{display:grid;grid-template-columns:repeat(5,1fr);gap:8px;margin-top:18px}.navq{aspect-ratio:1;border:1px solid var(--line);background:#fff;border-radius:10px;color:var(--navy);font-size:12px;font-weight:700;position:relative}.navq.active{outline:2px solid var(--navy);outline-offset:1px}.navq.correct{background:#edf7f2;color:var(--success);border-color:#cde6da}.navq.retry{background:#fff8ea;color:var(--warning);border-color:#ecdcae}.navq.flagged:after{content:"★";position:absolute;right:-4px;top:-7px;color:var(--red);font-size:11px}.sidebar-actions{display:grid;gap:8px;margin-top:18px}
.question-card{padding:28px}.crumb{font-size:12px;font-weight:700;color:var(--red);text-transform:uppercase;letter-spacing:.09em;margin-bottom:10px}.question-title{font-size:25px;line-height:1.35;color:var(--navy);margin:0 0 24px}.question-input{width:100%;max-width:360px;border:1px solid var(--line);border-radius:14px;padding:16px;font-size:18px;outline:none}.question-input:focus{border-color:var(--navy2);box-shadow:0 0 0 3px rgba(49,83,127,.1)}.feedback{margin:18px 0 0;padding:14px 16px;border-radius:13px;font-weight:600}.feedback.correct{background:#edf7f2;color:var(--success)}.feedback.retry{background:#fff8ea;color:var(--warning)}.q-actions{display:flex;justify-content:space-between;gap:12px;margin-top:24px;flex-wrap:wrap}.q-actions-left,.q-actions-right{display:flex;gap:10px}.flag-active{color:var(--red)!important;border-color:#e5b5b5!important;background:#fffafa!important}
.guide{padding:18px 20px;border-left:4px solid var(--red);background:#fffafa;margin-bottom:18px;border-radius:12px}.guide h4{margin:0 0 8px;color:var(--navy)}.guide p{margin:6px 0;line-height:1.5}.example{background:white;border:1px solid #efdede;padding:12px 14px;border-radius:10px;margin-top:10px}.support{margin-top:18px;padding:16px;border-radius:13px;background:var(--soft);border:1px solid var(--line)}.support h4{margin:0 0 8px;color:var(--navy)}.support-item{padding:10px 0;border-top:1px solid var(--line)}.support-item:first-of-type{border-top:0}.support-item a{color:var(--navy);font-weight:700;text-decoration:none}.support-item a:hover{text-decoration:underline}
.save-state{font-size:12px;color:var(--muted);min-height:16px}.empty{padding:26px;color:var(--muted);text-align:center}.loading{min-height:60vh;display:flex;align-items:center;justify-content:center;color:var(--muted)}
@media(max-width:820px){.login-wrap{grid-template-columns:1fr}.login-art{display:none}.topbar{padding:0 16px}.page{padding:22px 14px 48px}.hero{padding:24px;display:block}.hero h1{font-size:28px}.hero-badge{display:inline-block;margin-top:16px}.assignment-shell{grid-template-columns:1fr}.sidebar{position:static}.navigator{grid-template-columns:repeat(10,1fr)}.question-card{padding:22px}.assignment-card{grid-template-columns:1fr}.assignment-card .btn{width:100%}}
@media(max-width:520px){.navigator{grid-template-columns:repeat(5,1fr)}.student-name{display:none}.q-actions-left,.q-actions-right{width:100%}.q-actions .btn{flex:1}.login-panel{padding:24px}}

.teacher-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin-top:18px}
.stat-card{padding:18px}.stat-card span{display:block;color:var(--muted);font-size:12px;font-weight:700;text-transform:uppercase;letter-spacing:.06em}.stat-card strong{display:block;color:var(--navy);font-size:28px;margin-top:6px}
.teacher-list{display:grid;gap:12px}.teacher-row{padding:18px;display:grid;grid-template-columns:1.8fr repeat(4,.75fr) auto;gap:18px;align-items:center}.teacher-main h3{margin:8px 0 5px;color:var(--navy)}.metric span{display:block;color:var(--muted);font-size:11px;text-transform:uppercase;letter-spacing:.05em}.metric strong{display:block;color:var(--navy);font-size:20px;margin-top:4px}
.teacher-detail{overflow:hidden}.detail-head,.detail-row{display:grid;grid-template-columns:2.2fr .9fr .7fr .6fr .7fr .5fr .8fr;gap:12px;align-items:center;padding:14px 18px}.detail-head{background:var(--soft2);color:var(--navy);font-size:12px;text-transform:uppercase;letter-spacing:.04em}.detail-row{border-top:1px solid var(--line);font-size:13px}.detail-row>div:first-child{display:grid;gap:3px}.detail-row span{color:var(--muted)}
@media(max-width:900px){.teacher-stats{grid-template-columns:repeat(2,1fr)}.teacher-row{grid-template-columns:1fr 1fr}.teacher-main{grid-column:1/-1}.teacher-detail{overflow-x:auto}.detail-head,.detail-row{min-width:820px}}


.glossary-term{
  display:inline;
  border:0;
  border-bottom:1px dotted currentColor;
  background:transparent;
  color:inherit;
  font:inherit;
  padding:0;
  cursor:pointer;
  text-align:inherit;
}
.glossary-term:hover,.glossary-term:focus{
  background:rgba(31,78,121,.08);
  border-bottom-style:solid;
  outline:none;
}
.glossary-term span{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  width:14px;
  height:14px;
  margin-left:3px;
  border:1px solid currentColor;
  border-radius:50%;
  font-size:9px;
  line-height:1;
  vertical-align:2px;
  opacity:.65;
}
.glossary-bubble{
  position:fixed;
  z-index:1000;
  padding:14px 16px;
  border:1px solid var(--line);
  border-radius:12px;
  background:white;
  box-shadow:0 12px 32px rgba(10,30,50,.18);
  font-size:14px;
  line-height:1.45;
}
.glossary-bubble-head{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  margin-bottom:6px;
  color:var(--navy);
}
.glossary-close{
  border:0;
  background:transparent;
  font-size:22px;
  line-height:1;
  cursor:pointer;
  color:inherit;
}
.glossary-example{
  margin-top:8px;
  padding-top:8px;
  border-top:1px solid var(--line);
  font-size:12px;
  color:var(--muted);
}

.equation-answer-row{display:flex;align-items:center;gap:12px;max-width:440px}.equation-answer-label{font-size:22px;font-weight:700;color:var(--navy);white-space:nowrap}.equation-answer-row .question-input{min-width:0;flex:1}