body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: #1e1e2f;
  font-family: Arial, sans-serif;
}

.calculator {
  background: #2d2d44;
  padding: 20px;
  border-radius: 15px;
  box-shadow: 0px 8px 20px rgba(0, 0, 0, 0.3);
}

#display {
  width: 100%;
  height: 50px;
  font-size: 1.5em;
  margin-bottom: 15px;
  text-align: right;
  padding: 10px;
  border: none;
  border-radius: 8px;
  background: #12122b;
  color: white;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 70px);
  gap: 10px;
}

button {
  padding: 20px;
  font-size: 1.2em;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  background: #3b3b5c;
  color: white;
  transition: 0.2s;
}

button:hover {
  background: #57577d;
}

.equal {
  grid-column: span 2;
  background: #ff6b6b;
}

.equal:hover {
  background: #ff4b4b;
}