*{
  box-sizing:border-box;
}

body{
  margin:0;
  padding:16px;
  font-family:'Anek Telugu', sans-serif;
  background:#f4f7fb;
}

h1{
  text-align:center;
  margin-bottom:12px;
}

.controls{
  display:flex;
  flex-wrap:wrap;
  justify-content:center;
  gap:10px;
  margin-bottom:10px;
}

.controls select,
.controls button{
  font-family:'Anek Telugu', sans-serif;
  font-size:16px;
  padding:6px 10px;
}

#score{
  text-align:center;
  font-size:18px;
  margin-bottom:10px;
}

.problem{
  max-width:380px;
  margin:0 auto;
  background:#fff;
  padding:18px;
  border-radius:12px;
  box-shadow:0 4px 10px rgba(0,0,0,0.12);
  text-align:center;
}

.pv-grid{
  display:grid;
  justify-content:center;
  row-gap:8px;
}

.pv-cell{
  width:42px;
  height:46px;
  display:flex;
  align-items:center;
  justify-content:center;
  font-size:24px;
}

.op{
  font-weight:bold;
}

.line{
  grid-column:1 / -1;
  border-top:2px solid #000;
  margin:8px 0;
}

.answerSingle{
  grid-column:1 / -1;
  display:flex;
  justify-content:center;
  margin-top:10px;
}

.answerSingle input{
  width:160px;
  height:52px;
  font-size:26px;
  text-align:center;   /* NORMAL LTR */
  direction:ltr;
  border:2px solid #444;
  border-radius:6px;
  font-family:'Anek Telugu', sans-serif;
  padding:6px 10px;
}

.actions{
  text-align:center;
  margin-top:14px;
}

.actions button{
  margin:4px;
  padding:8px 16px;
  font-size:16px;
}

.correct{
  background:#c9f7c9;
  animation:blink .4s 3;
}

.wrong{
  background:#f7c9c9;
  animation:blink .4s 3;
}

@keyframes blink{
  50%{opacity:.4}
}

@media(max-width:480px){
  .pv-cell{
    width:38px;
    height:42px;
    font-size:22px;
  }
  .answerSingle input{
    width:140px;
    height:48px;
    font-size:24px;
  }
}