* {
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
}

body {
  background: radial-gradient(circle at top left, #222, #000);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  color: white;
}

.calculator-wrapper {
  width: 300px;
}

.calculator {
  background: #111;
  border-radius: 20px;
  box-shadow: 0 5px 20px rgba(255, 255, 255, 0.05);
  padding: 20px;
}

.display {
  text-align: right;
  background: #1b1b1b;
  border-radius: 10px;
  padding: 10px;
  margin-bottom: 15px;
}

#history {
  font-size: 0.8rem;
  color: #888;
  height: 20px;
}

#input {
  width: 100%;
  background: transparent;
  border: none;
  color: white;
  font-size: 1.8rem;
  outline: none;
  text-align: right;
}

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

.btn {
  background: #222;
  border: none;
  color: white;
  padding: 15px;
  border-radius: 10px;
  font-size: 1.1rem;
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
}

.btn:hover {
  background: #333;
  transform: scale(1.05);
}

.operator {
  background: #ff9500;
}

.operator:hover {
  background: #ffa733;
}

.equal {
  grid-column: span 2;
  background: #28a745;
}

.equal:hover {
  background: #2ecc71;
}