body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-image: linear-gradient(135deg, #5aa59d, #b3af3c);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.calculator {
  background-color: #257b2f;
  border: 3px solid #000;
  border-radius: 15px;
  padding: 20px;
  width: 300px;
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.3);
}

.calculator-display {
  width: 100%;
  height: 50px;
  font-size: 24px;
  text-align: right;
  padding: 10px;
  margin-bottom: 20px;
  border: none;
  border-radius: 8px;
  background-color: #a8a8a8;
  box-sizing: border-box;
}

.buttons {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.buttons-row {
  display: flex;
  justify-content: space-between;
}

button {
  width: 22%;
  padding: 15px 0;
  font-size: 18px;
  border: none;
  border-radius: 8px;
  background-color: #ffffff;
  cursor: pointer;
  transition: background-color 0.2s ease;
}

button:hover {
  background-color: #c0c0c0;
}

button:active {
  background-color: #a0a0a0;
}

button.wide {
  width: 47%;
}