body {
  font-family: Arial, sans-serif;
  background-color: #f4f4f4;
}

header {
  background-color: #333;
  color: #fff;
  text-align: center;
  padding: 1rem 0;
}



main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem;
}
.container {
  width: auto;
  max-width: 600px;
  margin: 0 auto;
  padding: 20px;
  background-color: #fff;
  border-radius: 5px;
  box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.2);
  display: flex;
  justify-content: center;
}

  body {
    font-family: Arial, sans-serif;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background-color: #f4f4f4;
  }
  .calculator {
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.2);
    padding: 20px;
    width: 300px;
  }
  input[type="text"] {
    width: 280px;
    font-size: 24px;
    padding: 10px;
    margin-bottom: 10px;
    border: none;
    border-bottom: 2px solid #ccc;
    outline: none;
  }
  .btn-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
  }
  button {
    font-size: 20px;
    padding: 15px;
    border: none;
    border-radius: 5px;
    background-color: #f2f2f2;
    cursor: pointer;
  }
  button.operator {
    background-color: #f0a500;
    color: #fff;
  }
  button.clear {
    background-color: #ff4c4c;
    color: #fff;
  }
  button.equal {
    background-color: #00a86b;
    color: #fff;
    
  }
  .voltar {
    font-size: 18px;
    margin-top: 10px;
    padding: 10px 20px;
    color: #fff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    margin-top: 10px;
  }