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



body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: #d6d4d4;
  font-family: Arial, sans-serif;
}

.calculator {
  background: rgb(22, 21, 21);
  padding: 20px;
  border-radius: 10px;
  border: 5px solid rgb(255, 38, 0);
  width: 260px;
}

#display {
  width: 100%;
  height: 40px;
  font-size: 1.5rem;
  text-align: right;
  padding: 5px 10px;
  margin-bottom: 10px;
  border: 1px solid #f8f3f3;
  border-radius: 5px;
  background-color: #f8f3f3;
}

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

button {
  font-size: 1.2rem;
  padding: 15px;
  border: none;
  background: #999595;
  border-radius: 5px;
  cursor: pointer;
  transition: background 0.2s;
}

button:hover {
  background: #fde9e9;
}

.zero {
  grid-column: span 2;
}