body {
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  
 .titulo{
    font-family: 'Times New Roman', Times, serif;
  }

  .titulo {
    float: left;
    padding: 1%;
    color: white;
    background-color: rgb(17, 16, 16);
    width: 800px;
    border: 5px solid black;
    text-align: center;
    margin-bottom: 20px;
  }
  
  .formulario {
    float: left;
    padding: 1%;
    color: rgb(20, 20, 20);
    background-color: rgb(230, 226, 227);
    width: 800px;
    border: 5px solid black;
    text-align: left;
  }
  
  .btn-operacion {
    background-color: #0a0a0a;
    color: white;
    border: none;
    font-weight: bold;
    padding: 10px 20px;
    border-radius: 5px;
  }
  
  .btn-operacion:hover {
    background-color: #0a0a0a;
  }
  
  .btn-borrar {
    background-color: #0f0d0d;
    color: white;
    border: none;
    font-weight: bold;
    padding: 10px 20px;
    border-radius: 5px;
  }
  
  .btn-borrar:hover {
    background-color: #050405;
  }