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

body {
  background: #f1f2f6;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  font-family: 'Segoe UI', sans-serif;
}

.calculator {
  background: #2f3542;
  padding: 20px;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
  width: 320px;
}

#display {
  width: 100%;
  height: 60px;
  font-size: 28px;
  text-align: right;
  padding: 10px;
  margin-bottom: 20px;
  border: none;
  border-radius: 8px;
  background: #ced6e0;
}

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

.btn {
  padding: 20px;
  font-size: 20px;
  background: #57606f;
  color: #fff;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s ease;
}

.btn:hover {
  background: #70a1ff;
}

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

.equals {
  background: #ffa502;
}

.equals:hover {
  background: #ff7f50;
}

.cb {
 color: #ffa502;
}

.cb:hover {
    background: #3963b1;
}

.op {
    color: #ffa502;
}

.op:hover {
    background: #3963b1;
}