body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  background-color: #121212;
  font-family: 'Arial', sans-serif;
}

.calculator {
  max-width: 320px;
  background-color: #1e1e1e;
  padding: 25px;
  border-radius: 10px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
  transition: transform 0.3s;
}

.calculator:hover {
  transform: scale(1.05);
}

#result {
  width: 100%;
  height: 50px;
  font-size: 28px;
  text-align: right;
  padding: 10px;
  box-sizing: border-box;
  margin-bottom: 15px;
  border: 2px solid #333;
  border-radius: 5px;
  background-color: #333;
  color: #ffffff;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-gap: 15px;
}

button {
  width: 100%;
  height: 50px;
  font-size: 20px;
  background-color: #6a0dad;  /* Purple background color */
  color: #ffffff;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.3s, transform 0.3s;
}

button:hover {
  background-color: #7b1fa2;  /* Slightly lighter purple */
  transform: translateY(-2px);
}

button:active {
  background-color: #4a0072;  /* Darker purple */
}