body {
  font-family: 'Segoe UI', sans-serif;
  margin: 0;
  padding: 20px;
  background: #f4f4f4;
  color: #333;
}

h1 {
  text-align: center;
  color: #0078D7;
}

#buttonsContainer {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-bottom: 20px;
}

button {
  background: #0078D7;
  color: white;
  border: none;
  border-radius: 6px;
  padding: 12px 20px;
  font-size: 16px;
  cursor: pointer;
  transition: background 0.3s;
}

button:hover {
  background: #005fa3;
}

.input-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 10px 0;
  padding: 10px;
  background: white;
  border-radius: 6px;
}

.overlay {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.6);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 10;
}

.keypad {
  background: white;
  padding: 20px;
  border-radius: 10px;
  width: 300px;
  text-align: center;
}

.keys {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.keys button {
  font-size: 24px;
  padding: 15px;
  border-radius: 8px;
  background: #c3c3c3;
  border: 1px solid #ccc;
}

#keypadDisplay {
  font-size: 32px;
  margin-bottom: 10px;
}

@media (max-width: 600px) {
  .keypad {
    width: 90%;
  }

  button {
    font-size: 14px;
    padding: 10px;
  }
}