:root{
  --bg:#f6f8ff;
  --card:#ffffff;
  --text:#14213d;
  --muted:#5b6475;
  --line:#e6e9f5;
  --primary:#5b7cfa;
  --primary2:#3f63ff;
  --ok:#16a34a;
  --bad:#dc2626;
  --shadow: 0 10px 24px rgba(20,33,61,.10);
  --r: 18px;
  --max: 1050px;
}

*{box-sizing:border-box}

body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Arial;
  color:var(--text);
  background:
    radial-gradient(1200px 400px at 20% -10%, rgba(91,124,250,.16), transparent 60%),
    radial-gradient(900px 380px at 85% 0%, rgba(63,99,255,.10), transparent 60%),
    var(--bg);
}

.wrap{max-width:var(--max); margin:0 auto; padding:18px}

header{
  display:flex; gap:14px; align-items:center; justify-content:space-between;
  padding:14px 14px;
  border:1px solid var(--line);
  background:rgba(255,255,255,.72);
  backdrop-filter: blur(8px);
  border-radius: var(--r);
  box-shadow: var(--shadow);
  position: sticky;
  top: 10px;
  z-index: 5;
}

.brand{display:flex; align-items:center; gap:12px; min-width: 240px}

.logo{
  width:40px; height:40px; border-radius:14px;
  background: linear-gradient(135deg, var(--primary), var(--primary2));
  display:grid; place-items:center;
  color:#fff; font-weight:900;
  box-shadow: 0 10px 18px rgba(91,124,250,.20);
  user-select:none;
}

.titles{line-height:1.1}
.titles .h1{font-weight:900; letter-spacing:.2px; font-size:14px}
.titles .h2{color:var(--muted); font-size:12px; margin-top:4px}

.controls{display:flex; gap:10px; align-items:center; flex-wrap:wrap; justify-content:flex-end}

.pill{
  border:1px solid var(--line);
  background:#fff;
  padding:10px 12px;
  border-radius:999px;
  display:flex; align-items:center; gap:8px;
  box-shadow: 0 8px 14px rgba(20,33,61,.06);
}

.pill b{font-size:12px}

.toggle{display:flex; gap:6px; align-items:center; font-size:12px; color:var(--muted)}

.btn{
  border:1px solid var(--line);
  background:#fff;
  padding:10px 12px;
  border-radius: 12px;
  cursor:pointer;
  font-weight:700;
  color: var(--text);
  box-shadow: 0 8px 14px rgba(20,33,61,.06);
}

.btn:active{transform: translateY(1px)}

.btn.primary{
  border-color: rgba(91,124,250,.35);
  background: linear-gradient(135deg, rgba(91,124,250,.14), rgba(63,99,255,.10));
  color:#0f1c3a;
}

.btn.small{padding:8px 10px; font-size:12px; border-radius:10px}

main{padding:16px 2px 28px}

.card{
  background: var(--card);
  border:1px solid var(--line);
  border-radius: var(--r);
  box-shadow: var(--shadow);
  padding:16px;
}

.sectionTitle{
  display:flex; align-items:center; justify-content:space-between; gap:10px;
  margin:0 0 10px;
}

.card h2{margin:0; font-size:16px; letter-spacing:.2px}
.card p{margin:0; color:var(--muted); line-height:1.35}

.hint{color:var(--muted); font-size:12px}

.btnRow{display:flex; gap:10px; flex-wrap:wrap; margin-top:10px}

.feedback{
  margin-top:10px;
  padding:10px 12px;
  border-radius: 14px;
  border:1px solid var(--line);
  background: rgba(20,33,61,.02);
  color: var(--muted);
  font-size:12px;
  line-height:1.35;
  min-height: 42px;
}

.feedback.ok{
  border-color: rgba(22,163,74,.25);
  background: rgba(22,163,74,.08);
  color:#0c3b1f;
}

.feedback.bad{
  border-color: rgba(220,38,38,.22);
  background: rgba(220,38,38,.08);
  color:#4a0d0d;
}

.qCard{
  border:1px solid var(--line);
  border-radius: 16px;
  padding:14px;
  background:#fff;
  box-shadow: 0 10px 18px rgba(20,33,61,.08);
}

.qHead{display:flex; align-items:flex-start; justify-content:space-between; gap:12px; margin-bottom:10px}
.qHead h3{margin:0; font-size:14px}
.qHead .meta{font-size:12px; color:var(--muted)}

.options{display:grid; gap:10px; grid-template-columns: 1fr 1fr}
@media (max-width: 520px){ .options{grid-template-columns: 1fr} }

.opt{
  display:flex; gap:10px; align-items:flex-start;
  border:1px solid var(--line);
  border-radius: 14px;
  padding:10px;
  background: rgba(20,33,61,.02);
  cursor:pointer;
  user-select:none;
}

.opt input{margin-top:2px}
.opt b{font-size:13px}
.opt span{display:block; margin-top:2px; color:var(--muted); font-size:12px; line-height:1.25}

/* Learn details */
.learnDetails{
  margin-top:14px;
  border:1px solid var(--line);
  border-radius: var(--r);
  background: rgba(255,255,255,.55);
  box-shadow: 0 10px 24px rgba(20,33,61,.06);
  overflow:hidden;
}

.learnDetails > summary{
  cursor:pointer;
  list-style:none;
  padding:14px 16px;
  display:flex; align-items:center; justify-content:space-between; gap:12px;
  user-select:none;
  background:#fff;
  border-bottom:1px solid var(--line);
}

.learnDetails > summary::-webkit-details-marker{display:none}
.sumTitle{font-weight:900; font-size:14px}
.sumHint{color:var(--muted); font-size:12px}
.learnDetails .grid{padding:14px; margin-top:0}

/* Learning grid */
.grid{display:grid; gap:14px; grid-template-columns: 1fr 1fr}

@media (max-width: 900px){
  .grid{grid-template-columns: 1fr}
  header{position:static}
  .brand{min-width:unset}
}

/* =========================
   FLIP CARDS (CRITICAL AREA)
   ========================= */
.flipGrid{
  display:grid;
  gap:12px;
  grid-template-columns: repeat(3, 1fr);
}

@media (max-width: 900px){
  .flipGrid{grid-template-columns: repeat(2, 1fr)}
}
@media (max-width: 520px){
  .flipGrid{grid-template-columns: 1fr}
}

.flip{perspective:1000px}

.flipInner{
  position:relative;
  width:100%;
  /* ✅ CRITICAL: this is what your JS sets via --flipH */
  min-height: var(--flipH, 190px);
  transform-style:preserve-3d;
  transition:transform .55s ease;
  border-radius:16px;
}

.flip.isFlipped .flipInner{transform:rotateY(180deg)}

.face{
  position:absolute;
  inset:0;
  backface-visibility:hidden;
  border-radius:16px;
  border:1px solid var(--line);
  background:#fff;
  padding:14px;
  box-shadow: 0 10px 18px rgba(20,33,61,.08);

  display:flex;
  flex-direction:column;
  justify-content:space-between;
  gap:10px;

  /* ✅ prevent ugly overflow */
  overflow:hidden;
  word-break: break-word;
  overflow-wrap: anywhere;
  hyphens: auto;
}

.face .top{display:flex; align-items:flex-start; justify-content:space-between; gap:10px}

.badge{
  font-size:11px; font-weight:900; letter-spacing:.3px;
  padding:6px 10px;
  border-radius:999px;
  background: rgba(91,124,250,.10);
  border:1px solid rgba(91,124,250,.22);
  color:#1a2b5a;
  white-space:nowrap;
}

.face h3{
  margin:0;
  font-size:14px;
  letter-spacing:.2px;
  line-height:1.25;
}

.face p{
  margin:0;
  color:var(--muted);
  font-size:12px;
  line-height:1.35;
}

.flipBtn{
  align-self:flex-start;
  border:1px solid var(--line);
  background:#fff;
  padding:8px 10px;
  border-radius:12px;
  cursor:pointer;
  font-weight:800;
  font-size:12px;
}

.back{
  transform:rotateY(180deg);
  background: linear-gradient(135deg, rgba(91,124,250,.10), rgba(63,99,255,.08));
}

.back .badge{background:#fff}

.chips{display:flex; gap:8px; flex-wrap:wrap; margin-top:12px}

.chip{
  font-size:12px; font-weight:800;
  padding:6px 10px;
  border-radius:999px;
  border:1px solid var(--line);
  background: rgba(20,33,61,.02);
  color: var(--text);
}

footer{
  margin-top:14px;
  color:var(--muted);
  font-size:12px;
  text-align:center;
  padding:14px 0 6px;
}

/* Shake on wrong */
.shake{ animation: shake .25s linear 0s 2; }
@keyframes shake{
  0%{transform:translateX(0)}
  25%{transform:translateX(-4px)}
  50%{transform:translateX(4px)}
  75%{transform:translateX(-3px)}
  100%{transform:translateX(0)}
}