body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-image: url("bg.avif");
    background-size: cover;
    background-repeat: repeat;
  }
  
  h1 {
    font-family: 'Times New Roman', Times, serif;
    color: black;
    text-decoration: underline;
    text-align: center;
    margin-top: 70px;
  }
  
  .container {
    max-width: 300px;
    margin: auto;
    margin-top: 20px;
    padding: 20px;
    border: 1px solid #ccc;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    background-color: rgb(35, 32, 38);
    height: 350px;
  }
  
  #screen {
    width: 93%;
    padding: 10px;
    margin-bottom: 10px;
    font-size: 24px;
    text-align: right;
    margin-top: 5px;
  }
  
  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: 10px;
    margin-top: 20px;
  }
  
  button {
    padding: 10px;
    font-size: 18px;
    text-align: center;
    cursor: pointer;
    border: none;
    background-color: #f0f0f0;
  }
  
  button.op {
    background-color: #fe750c;
    color: white;
  }
  
  button:hover {
    background-color: #e0e0e0;
  }
  
  button:active {
    background-color: #d9d9d9;
  }
  
  @media (min-width: 768px) {
    .container {
      max-width: 400px;
      margin-left: 20px;
      margin-right: 20px;
    }
  
    h1 {
      margin-left: 0;
    }
  }
  
  @media (min-width: 992px) {
    .container {
      max-width: 500px;
      margin-left: auto;
      margin-right: auto;
    }
  }