body {
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: linear-gradient(135deg, #2c2c2c, #1a1a1a); /* dark metallic background */
}

.calculator {
  background: linear-gradient(145deg, #d4af37, #b8860b); /* gold frame */
  padding: 25px;
  border-radius: 15px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.6);
}

#display {
  width: 100%;
  height: 60px;
  margin-bottom: 15px;
  padding: 8px;
  font-size: 1.4rem;
  text-align: right;
  border: none;
  border-radius: 8px;
  background: linear-gradient(145deg, #f0f0f0, #c0c0c0); /* silver display */
  color: #222;
  box-shadow: inset 2px 2px 6px rgba(0,0,0,0.3);
  pointer-events: auto;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 70px);
  gap: 12px;
}

button {
  width: 100%;
  height: 55px;
  font-size: 1.2rem;
  font-weight: bold;
  border: none;
  border-radius: 8px;
  background: linear-gradient(145deg, #444, #222); /* metallic buttons */
  color: #fff;
  cursor: pointer;
  box-shadow: 3px 3px 8px rgba(0,0,0,0.5);
  transition: all 0.2s ease-in-out;
}

button:hover {
  background: linear-gradient(145deg, #666, #333);
  transform: translateY(-2px);
}

.clear {
  background: linear-gradient(145deg, #b22222, #8b0000); /* red for clear */
  color: white;
}

.equal {
  grid-column: span 2;
  background: linear-gradient(145deg, #ff8c00, #ff4500); /* orange highlight for equals */
  color: white;
}