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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #0f2027, #203a43, #2c5364);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  color: #fff;
}

.calculator {
  background-color: #1e1e2f;
  padding: 25px;
  border-radius: 20px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.6);
  width: 320px;
}

#display {
  width: 100%;
  height: 60px;
  background-color: #2a2a3b;
  color: #fff;
  font-size: 28px;
  padding: 10px;
  text-align: right;
  border: none;
  border-radius: 12px;
  margin-bottom: 20px;
  outline: none;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

button {
  height: 60px;
  font-size: 22px;
  border: none;
  border-radius: 12px;
  background-color: #3b3b51;
  color: #ffffff;
  cursor: pointer;
  transition: background 0.3s, transform 0.1s;
}

button:hover {
  background-color: #555578;
}

button:active {
  background-color: #6e6ea0;
  transform: scale(0.96);
}

/* Destaque para botões de operação e igual */
button:nth-child(2),
button:nth-child(3),
button:nth-child(4),
button:nth-child(8),
button:nth-child(12),
button:nth-child(16) {
  background-color: #ff8c00;
  color: #fff;
}

button:nth-child(2):hover,
button:nth-child(3):hover,
button:nth-child(4):hover,
button:nth-child(8):hover,
button:nth-child(12):hover,
button:nth-child(16):hover {
  background-color: #ffa733;
}