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

body {
  background: #111;
  font-family: 'Segoe UI', sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.calculator {
  width: 720px;
  background: #1e1e1e;
  border-radius: 16px;
  padding: 25px;
  box-shadow: 0 0 30px rgba(0, 255, 255, 0.2);
}

.display-area {
  background: #000;
  color: #0f0;
  padding: 20px;
  border-radius: 12px;
  text-align: right;
  font-size: 2.5rem;
  margin-bottom: 20px;
  min-height: 70px;
  overflow-x: auto;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 12px;
}

button {
  padding: 20px;
  font-size: 1.3rem;
  background: #2b2b2b;
  color: #fff;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.2s;
}

button:hover {
  background: #3c3c3c;
}

.op {
  background: #2962ff;
  color: white;
}

.func {
  background: #ffab00;
  color: black;
}

.equal {
  background: #00c853;
  color: white;
}