/* ===== GRE Quant Mastery — stylesheet ===== */
:root{
  --bg:#0f172a;            /* slate-900 */
  --bg-soft:#1e293b;       /* slate-800 */
  --panel:#ffffff;
  --ink:#0f172a;
  --ink-soft:#475569;
  --line:#e2e8f0;
  --brand:#4f46e5;         /* indigo-600 */
  --brand-dark:#3730a3;
  --brand-soft:#eef2ff;
  --accent:#0ea5e9;
  --good:#16a34a;
  --good-soft:#dcfce7;
  --bad:#dc2626;
  --bad-soft:#fee2e2;
  --warn:#d97706;
  --warn-soft:#fef3c7;
  --easy:#16a34a;
  --medium:#d97706;
  --hard:#dc2626;
  --shadow:0 1px 3px rgba(15,23,42,.08),0 8px 24px rgba(15,23,42,.06);
  --radius:14px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  color:var(--ink);
  background:#f1f5f9;
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%}

/* ---- top nav ---- */
.nav{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.9);backdrop-filter:saturate(180%) blur(10px);
  color:var(--ink);border-bottom:1px solid var(--line);
  box-shadow:0 1px 2px rgba(15,23,42,.04);
}
.nav-inner{
  max-width:1080px;margin:0 auto;padding:12px 20px;
  display:flex;align-items:center;gap:18px;flex-wrap:wrap;
}
.brand{font-weight:800;font-size:1.05rem;letter-spacing:.3px;color:var(--brand-dark);display:flex;align-items:center;gap:8px}
.brand:hover{text-decoration:none}
.nav-links{display:flex;gap:6px;flex-wrap:wrap;margin-left:auto}
.nav-links a{
  color:var(--ink-soft);padding:6px 12px;border-radius:8px;font-size:.92rem;font-weight:600;
}
.nav-links a:hover{background:var(--brand-soft);color:var(--brand-dark);text-decoration:none}
.nav-links a.active{background:var(--brand);color:#fff}

/* ---- layout ---- */
.wrap{max-width:1080px;margin:0 auto;padding:28px 20px 80px}
.narrow{max-width:820px}
.hero{
  background:linear-gradient(120deg,#eef2ff,#e0f2fe 70%,#f0fdfa);
  color:var(--ink);border:1px solid var(--line);border-radius:var(--radius);
  padding:38px 32px;margin-bottom:28px;box-shadow:var(--shadow);
}
.hero h1{margin:0 0 8px;font-size:2rem;line-height:1.2;color:var(--brand-dark)}
.hero p{margin:6px 0;color:var(--ink-soft);max-width:680px}
.hero .target{display:inline-block;background:#fff;border:1px solid var(--brand);color:var(--brand-dark);
  padding:4px 14px;border-radius:999px;font-weight:700;margin-top:10px}

h2.section{font-size:1.4rem;margin:34px 0 14px;display:flex;align-items:center;gap:10px}
h2.section .num{background:var(--brand);color:#fff;width:30px;height:30px;border-radius:8px;
  display:inline-flex;align-items:center;justify-content:center;font-size:.95rem;font-weight:800}
.lead{color:var(--ink-soft);max-width:760px}

/* ---- cards ---- */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:16px}
.card{
  background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
  padding:18px;box-shadow:var(--shadow);position:relative;transition:transform .12s,box-shadow .12s;
  display:flex;flex-direction:column;
}
.card.module{cursor:pointer}
.card.module:hover{transform:translateY(-3px);box-shadow:0 10px 30px rgba(79,70,229,.16)}
.card .ico{font-size:1.8rem}
.card h3{margin:8px 0 4px;font-size:1.08rem}
.card .blurb{color:var(--ink-soft);font-size:.9rem;flex:1}
.card .mod-foot{display:flex;align-items:center;justify-content:space-between;margin-top:12px;font-size:.82rem}
.card.locked{opacity:.62}
.lock-badge{position:absolute;top:14px;right:14px;font-size:1.1rem}
.order-pill{position:absolute;top:14px;left:14px;background:var(--brand-soft);color:var(--brand-dark);
  font-weight:800;font-size:.72rem;padding:3px 9px;border-radius:999px}

/* ---- progress ---- */
.bar{height:9px;background:#e2e8f0;border-radius:999px;overflow:hidden}
.bar>span{display:block;height:100%;background:linear-gradient(90deg,var(--brand),var(--accent));border-radius:999px;transition:width .5s}
.bar.good>span{background:linear-gradient(90deg,#16a34a,#4ade80)}
.bar.thin{height:6px}
.kpi-row{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:14px;margin:6px 0 8px}
.kpi{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px 16px;box-shadow:var(--shadow)}
.kpi .big{font-size:1.7rem;font-weight:800;color:var(--brand-dark);line-height:1}
.kpi .lbl{color:var(--ink-soft);font-size:.8rem;margin-top:4px;text-transform:uppercase;letter-spacing:.04em}

/* ---- buttons ---- */
.btn{display:inline-flex;align-items:center;gap:8px;background:var(--brand);color:#fff;border:none;
  padding:11px 20px;border-radius:10px;font-weight:700;font-size:.95rem;cursor:pointer;transition:background .12s,transform .08s}
.btn:hover{background:var(--brand-dark);text-decoration:none;color:#fff}
.btn:active{transform:translateY(1px)}
.btn.ghost{background:#fff;color:var(--brand);border:1.5px solid var(--brand)}
.btn.ghost:hover{background:var(--brand-soft)}
.btn.sm{padding:7px 13px;font-size:.85rem;border-radius:8px}
.btn.gray{background:#475569}
.btn.gray:hover{background:#334155}
.btn.good{background:var(--good)}
.btn.good:hover{background:#15803d}
.btn:disabled{opacity:.5;cursor:not-allowed}
.btn-row{display:flex;gap:10px;flex-wrap:wrap;margin-top:14px}

/* ---- panels / theory ---- */
.panel{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
  padding:22px 26px;box-shadow:var(--shadow);margin-bottom:20px}
.panel h3{margin-top:18px}
.panel h3:first-child{margin-top:0}
.panel table{border-collapse:collapse;width:100%;margin:12px 0;font-size:.92rem}
.panel th,.panel td{border:1px solid var(--line);padding:7px 10px;text-align:left}
.panel th{background:var(--brand-soft);color:var(--brand-dark)}
.panel ul{padding-left:22px}
.callout{border-left:4px solid var(--brand);background:var(--brand-soft);padding:12px 16px;border-radius:0 10px 10px 0;margin:14px 0}
.callout.tip{border-color:var(--good);background:var(--good-soft)}
.callout.trap{border-color:var(--bad);background:var(--bad-soft)}
.callout.ets{border-color:var(--accent);background:#e0f2fe}
.callout h4{margin:0 0 6px;font-size:.95rem}
.tag-list{display:flex;flex-direction:column;gap:8px}
sup{font-size:.72em}

/* example accordions */
details.ex,details.sol{border:1px solid var(--line);border-radius:10px;margin:10px 0;background:#fff;overflow:hidden}
details.ex>summary,details.sol>summary{
  cursor:pointer;padding:12px 16px;font-weight:700;list-style:none;background:#f8fafc;
  display:flex;align-items:center;gap:10px}
details.ex>summary::-webkit-details-marker,details.sol>summary::-webkit-details-marker{display:none}
details.ex>summary::before,details.sol>summary::before{content:"▸";color:var(--brand);font-weight:800}
details.ex[open]>summary::before,details.sol[open]>summary::before{content:"▾"}
.ex-body,.sol-body{padding:6px 18px 16px}
.sol-body .shortcut{border-left:4px solid var(--accent);background:#e0f2fe;padding:8px 14px;border-radius:0 8px 8px 0;margin-top:10px}

/* ---- questions / quiz ---- */
.q-toolbar{display:flex;gap:8px;flex-wrap:wrap;align-items:center;margin:6px 0 16px}
.chip{border:1.5px solid var(--line);background:#fff;color:var(--ink-soft);padding:6px 14px;border-radius:999px;
  cursor:pointer;font-size:.85rem;font-weight:700}
.chip.active{background:var(--brand);border-color:var(--brand);color:#fff}
.diff-badge{font-size:.7rem;font-weight:800;text-transform:uppercase;letter-spacing:.05em;padding:2px 9px;border-radius:999px;color:#fff}
.diff-easy{background:var(--easy)} .diff-medium{background:var(--medium)} .diff-hard{background:var(--hard)}
.type-badge{font-size:.68rem;font-weight:700;padding:2px 8px;border-radius:6px;background:#e2e8f0;color:var(--ink-soft)}

.q{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:18px 20px;margin-bottom:16px;box-shadow:var(--shadow)}
.q .q-head{display:flex;align-items:center;gap:8px;margin-bottom:8px;font-size:.78rem;color:var(--ink-soft)}
.q .q-head .qn{font-weight:800;color:var(--ink)}
.q .stem{font-size:1rem;margin:6px 0 12px}
.q .info{background:#f8fafc;border:1px dashed var(--line);padding:8px 12px;border-radius:8px;margin-bottom:10px;font-size:.95rem}
.qc-quantities{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:10px 0}
.qc-quantities .qbox{border:1px solid var(--line);border-radius:10px;padding:12px;background:#f8fafc}
.qc-quantities .qbox .lbl{font-size:.72rem;font-weight:800;color:var(--brand-dark);text-transform:uppercase;letter-spacing:.05em}
.qc-quantities .qbox .val{font-size:1.05rem;margin-top:4px}
.choices{list-style:none;padding:0;margin:0;display:flex;flex-direction:column;gap:8px}
.choices li{border:1.5px solid var(--line);border-radius:10px;transition:border-color .1s,background .1s}
.choices li:hover{border-color:var(--brand)}
.choices label{display:flex;gap:11px;align-items:flex-start;padding:11px 14px;cursor:pointer}
.choices .ltr{font-weight:800;color:var(--brand-dark);min-width:18px}
.choices li.correct{border-color:var(--good);background:var(--good-soft)}
.choices li.wrong{border-color:var(--bad);background:var(--bad-soft)}
.choices li.picked{border-width:2px}
.ne-input{font-size:1rem;padding:9px 12px;border:1.5px solid var(--line);border-radius:9px;width:180px}
.ne-input:focus{outline:none;border-color:var(--brand)}
.q-actions{display:flex;gap:10px;align-items:center;margin-top:12px;flex-wrap:wrap}
.verdict{font-weight:800;font-size:.92rem}
.verdict.ok{color:var(--good)} .verdict.no{color:var(--bad)}

/* quiz / test runner */
.quiz-bar{position:sticky;top:58px;z-index:30;background:var(--panel);border:1px solid var(--line);
  border-radius:12px;padding:12px 18px;box-shadow:var(--shadow);margin-bottom:18px;
  display:flex;align-items:center;gap:16px;flex-wrap:wrap}
.timer{font-variant-numeric:tabular-nums;font-weight:800;font-size:1.15rem;color:var(--brand-dark)}
.timer.low{color:var(--bad)}
.score-big{font-size:3rem;font-weight:800;line-height:1;color:var(--brand-dark)}
.band{display:inline-block;padding:6px 16px;border-radius:999px;font-weight:800;margin-top:8px}
.band.weak{background:var(--bad-soft);color:var(--bad)}
.band.inter{background:var(--warn-soft);color:var(--warn)}
.band.strong{background:#dbeafe;color:#1d4ed8}
.band.target{background:var(--good-soft);color:var(--good)}
.result-panel .score-big{margin-bottom:6px}
.result-breakdown{display:flex;gap:10px;flex-wrap:wrap;justify-content:center;margin:16px 0 6px}
.rb{font-weight:800;font-size:.95rem;padding:7px 15px;border-radius:999px;border:1.5px solid var(--line)}
.rb.ok{background:var(--good-soft);color:var(--good);border-color:var(--good)}
.rb.no{background:var(--bad-soft);color:var(--bad);border-color:var(--bad)}
.rb.sk{background:#f1f5f9;color:var(--ink-soft)}
.rb.pc{background:var(--brand-soft);color:var(--brand-dark);border-color:var(--brand)}
.ne-input.ne-correct{border-color:var(--good);background:var(--good-soft)}
.ne-input.ne-wrong{border-color:var(--bad);background:var(--bad-soft)}
.ne-ans{margin-left:10px;font-weight:700}
.ne-ans.ok{color:var(--good)} .ne-ans.no{color:var(--bad)}

/* gate */
.gate{border:1px solid var(--line);border-radius:12px;padding:16px 20px;margin:18px 0;background:#fff;box-shadow:var(--shadow)}
.gate.pass{border-color:var(--good);background:var(--good-soft)}
.gate .req{display:flex;justify-content:space-between;padding:6px 0;border-bottom:1px dashed var(--line);font-size:.92rem}
.gate .req:last-child{border-bottom:none}
.gate .req .met{color:var(--good);font-weight:800}
.gate .req .unmet{color:var(--ink-soft);font-weight:700}

/* error log / textarea */
textarea.note{width:100%;min-height:90px;border:1.5px solid var(--line);border-radius:10px;padding:11px;font:inherit;resize:vertical}
textarea.note:focus{outline:none;border-color:var(--brand)}
.log-item{border:1px solid var(--line);border-radius:10px;padding:10px 14px;margin:8px 0;background:#fff;display:flex;justify-content:space-between;gap:12px}
.log-item .meta{font-size:.75rem;color:var(--ink-soft)}
.muted{color:var(--ink-soft)}
.small{font-size:.85rem}
.center{text-align:center}
.hidden{display:none!important}

/* weak-topic dashboard bars */
.wt{display:flex;align-items:center;gap:12px;margin:8px 0}
.wt .name{min-width:190px;font-weight:600;font-size:.92rem}
.wt .bar{flex:1}
.wt .pct{min-width:54px;text-align:right;font-weight:800;font-variant-numeric:tabular-nums}
.wt.low .pct{color:var(--bad)} .wt.mid .pct{color:var(--warn)} .wt.hi .pct{color:var(--good)}

/* ---- vocabulary flashcards / quiz ---- */
.btn.wide{width:100%;justify-content:center}
.btn.danger{background:var(--bad)}
.btn.danger:hover{background:#b91c1c}
a.chip{text-decoration:none}
a.chip:hover{text-decoration:none}
.flashcard{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
  padding:26px 24px;box-shadow:var(--shadow);margin-bottom:18px}
.fc-prog{display:flex;justify-content:space-between;align-items:center;color:var(--ink-soft);
  font-size:.82rem;font-weight:700;margin-bottom:14px}
.fc-front{font-size:2.2rem;font-weight:800;color:var(--brand-dark);text-align:center;
  padding:26px 10px;line-height:1.25}
.fc-front.reverse{font-size:1.25rem;font-weight:600;color:var(--ink)}
.fc-back{border-top:1px dashed var(--line);margin:8px 0 18px;padding:16px 6px 4px;
  font-size:1.25rem;text-align:center;color:var(--ink)}
.fc-back-main{font-size:1.25rem}
.fc-sentence{margin-top:12px;font-size:1rem;font-style:italic;color:var(--ink-soft);
  background:var(--brand-soft);border-radius:10px;padding:10px 14px;line-height:1.5}
.fc-sentence strong{color:var(--brand-dark);font-style:normal}
.fc-toggle{display:block;margin:2px auto 14px}
.vocab-choices+.fc-sentence,.vocab-choice~.fc-sentence{text-align:center;margin:0 0 14px}
.fc-rate{justify-content:center}
.fc-rate .btn{min-width:130px;justify-content:center}
.vocab-choices{display:flex;flex-direction:column;gap:10px;margin:8px 0 16px}
.vocab-choice{text-align:left;border:1.5px solid var(--line);background:#fff;color:var(--ink);
  padding:13px 16px;border-radius:10px;font:inherit;font-size:.98rem;cursor:pointer;transition:border-color .1s,background .1s}
.vocab-choice:hover:not(:disabled){border-color:var(--brand);background:var(--brand-soft)}
.vocab-choice:disabled{cursor:default}
.vocab-choice.right{border-color:var(--good);background:var(--good-soft);font-weight:700}
.vocab-choice.wrong{border-color:var(--bad);background:var(--bad-soft)}

footer{border-top:1px solid var(--line);margin-top:50px;padding:24px 20px;text-align:center;color:var(--ink-soft);font-size:.85rem}

@media(max-width:620px){
  .hero{padding:26px 20px}
  .hero h1{font-size:1.55rem}
  .qc-quantities{grid-template-columns:1fr}
  .wt .name{min-width:120px}
  .nav-links{width:100%;margin-left:0}
}
@media print{.nav,.btn,.q-toolbar,footer{display:none}}