body {
  margin: 0;
  padding: 0;
  font-family: 'Itim', cursive;
  background: #1a1a1a;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.calculator {
  background: #2c2c2c;
  border-radius: 20px;
  padding: 20px;
  width: 250px;
  box-shadow: 0 0 20px rgba(0,0,0,0.5);
  text-align: center;
}

.calculator input {
  width: 100%;
  height: 50px;
  border: none;
  border-radius: 10px;
  margin-bottom: 15px;
  font-size: 20px;
  background: #111;
  color: white;
  text-align: center;
  box-shadow: inset 0 0 8px #000;
}

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

button {
  height: 50px;
  border: none;
  border-radius: 10px;
  font-size: 18px;
  background: #444;
  color: white;
  transition: 0.2s;
}
button:focus {
  outline: none;
  box-shadow: none;
}

button:hover {
  background: #555;
}

button:active {
  transform: scale(0.95);
}

.operator { background: #f57c00; }
.equals { background: #43a047; }
.disabled {
  pointer-events: none;
  opacity: 0.5;
}