body {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  font-family: Arial, sans-serif;
  background-color: #f4f4f9;
}

.calculator {
  width: 250px;
  background: #333;
  padding: 15px;
  border-radius: 8px;
  box-shadow: 0px 4px 10px rgba(0, 0, 0, 0.2);
}

#display {
  background: #222;
  color: white;
  text-align: right;
  padding: 20px;
  border-radius: 4px;
  margin-bottom: 10px;
  min-height: 40px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

#display .money {
  font-size: 2em;
  font-weight: bold;
}

#display .money-text {
  font-size: 0.8em;
  color: #888;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.btn {
  width: 2.8em;
  height: 2.8em;
  font-size: 1.2em;
  color: white;
  background-color: #444;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: background 0.2s;
}

.btn:hover {
  background-color: #555;
}

.btn:active {
  background-color: #666;
}

.btn.large {
  grid-column: span 2;
}

.btn.operator {
  background-color: #ff9f0a;
}

.btn.qr {
  background-color: #1c437e;
}
  
.modal {
  display: none;
  position: fixed;
  z-index: 1;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0,0,0,0.4);
}

.modal-content {
  background-color: #fefefe;
  margin: 15% auto;
  padding: 20px;
  border: 1px solid #888;
  width: 80%;
  max-width: 400px;
  text-align: center;
  border-radius: 8px;
}

.bank-info-display {
  padding: 10px;
  background-color: #f4f4f9;
  color: #333;
  text-align: center;
  font-weight: bold;
  margin-bottom: 10px;
}

#qr-image {
  width: 100%;
}