body {
  font-family: Arial, sans-serif;
  background: #f2f2f2;
  margin: 0;
  padding: 0;
}
.app {
  max-width: 500px;
  margin: auto;
  padding: 20px;
}
h1 {
  text-align: center;
}
.balance-box {
  background: white;
  padding: 15px;
  margin: 15px 0;
  border-radius: 10px;
  font-size: 18px;
  text-align: center;
}
form {
  background: white;
  padding: 15px;
  border-radius: 10px;
}
form label {
  display: block;
  margin-top: 10px;
}
form input, form select {
  width: 100%;
  padding: 10px;
  margin-top: 5px;
}
form button {
  width: 100%;
  margin-top: 15px;
  background: #00a651;
  color: white;
  padding: 12px;
  border: none;
  font-size: 16px;
  border-radius: 8px;
}
.bottom-btn {
  text-align: center;
  margin-top: 30px;
}
.bottom-btn button {
  background: #0066cc;
  color: white;
  border: none;
  padding: 12px 24px;
  font-size: 16px;
  border-radius: 8px;
}