body {
  margin: 0;
  font-family: sans-serif;
  background: linear-gradient(135deg, #0f2027, #203a43, #2c5364);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.calculator {
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  padding: 20px;
  border-radius: 16px;
  box-shadow: 0 0 20px rgba(0, 255, 255, 0.15);
  width: 320px;
}

.display {
  background: rgba(0, 0, 0, 0.75);
  color: #39ff14;
  font-size: 2rem;
  padding: 15px;
  border-radius: 10px;
  text-align: right;
  margin-bottom: 15px;
  min-height: 60px;
  overflow-x: auto;
}

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

button {
  padding: 18px;
  font-size: 1.1rem;
  border: none;
  border-radius: 10px;
  background: #1e1e1e;
  color: white;
  cursor: pointer;
  transition: background 0.2s;
  box-shadow: 0 3px #00ffff20;
}

button:hover {
  background: #333;
}

button.op {
  background: #ff4a80;
}

button.op:hover {
  background: #ff709c;
}

button.func {
  background: #ff9100;
}

button.func:hover {
  background: #ffb347;
}

button.equal {
  background: #00e676;
  color: black;
  grid-column: span 2;
}

button.equal:hover {
  background: #1aff8c;
}