#acf-flashcards {
  max-width: 500px;
  margin: auto;
}
.acf-selector {
  text-align: center;
  margin-bottom: 15px;
}
.acf-selector label {
  margin-right: 5px;
  font-size: 1.1em;
}
#acf-timer {
  text-align: center;
  font-size: 1.2em;
  margin-bottom: 15px;
}
.acf-card-front, .acf-card-back {
  font-family: 'Arial', 'Tahoma', sans-serif;
  font-size: 2em;
  text-align: center;
  margin: 0 auto 20px;
  width: 80%;
  border: 2px solid #ddd;
  padding: 20px;
  border-radius: 10px;
}
.acf-controls {
  text-align: center;
}
.acf-controls button {
  margin: 0 10px;
  padding: 10px 20px;
  font-size: 1em;
}
#acf-score {
  text-align: center;
  font-size: 1.2em;
  margin-top: 15px;
}