* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

.calculadora {
  background-color: #2b2b3d;
  padding: 20px;
  border-radius: 16px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
  width: 320px;
}

#visor {
  width: 100%;
  height: 70px;
  margin-bottom: 15px;
  border: none;
  border-radius: 10px;
  background-color: #16161f;
  color: #fff;
  font-size: 2rem;
  text-align: right;
  padding: 0 15px;
}

.botoes {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.btn {
  padding: 18px 0;
  font-size: 1.2rem;
  border: none;
  border-radius: 10px;
  background-color: #3a3a4d;
  color: #fff;
  cursor: pointer;
  transition: background-color 0.2s;
}

.btn:hover {
  background-color: #4a4a60;
}

.cinza {
  background-color: #565669;
}

.laranja {
  background-color: #ff9500;
}

.laranja:hover {
  background-color: #e08600;
}

.igual {
  background-color: #ff9500;
  grid-column: span 2;
}

.zero {
  grid-column: span 2;
}