/* RESET */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Segoe UI', sans-serif;
}

body {
  background: #0f0f10;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.calculator {
  background: #1c1c1e;
  padding: 20px;
  border-radius: 25px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.5);
  width: 320px;
}

.display {
  background: #000;
  color: #ffd60a;
  font-size: 3rem;
  text-align: right;
  padding: 20px;
  border-radius: 15px;
  margin-bottom: 20px;
  overflow-x: auto;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 15px;
}

.btn {
  padding: 20px;
  font-size: 1.4rem;
  border: none;
  border-radius: 15px;
  background: #2c2c2e;
  color: #ffffff;
  cursor: pointer;
  transition: transform 0.1s ease, background 0.2s ease;
}

.btn:hover {
  background: #3a3a3c;
}

.btn:active {
  transform: scale(0.95);
}

.operator {
  background: #f5df4d;
  color: #000;
  font-weight: bold;
}

.equals {
  background: #ff5a36;
  color: #fff;
  grid-column: span 1;
}

.function {
  color: #4de1e1;
}

.zero {
  grid-column: span 2;
  }