<style>

* {
   box-sizing: border-box;     /* considera paddings y borders dentro de las dimensiones de los elementos y asegura que las cajas tengan iguales dimensiones */
}
 
img {
  display: block;              /* To center the image, we set left and right margin to auto, and make it into a block element */
  margin-top: 20px;
  margin-right: auto;
  margin-left: auto;
  width:15%;                   /* max size of img relative to its original size */
}

form {
      height: 170px;
      width: 400px;            /* Setting the width of the form (block-level element) prevents it
                                  from stretching out to the edges of its container (in this case the page).*/
      margin: auto;            /* In adition to width setting, this statement horizontally centers the form within its container. */
      border: 1px solid blue;
      paddle: 40px;
      font-family: Calibri;
      font-size: 16px;
}

div {
     margin-top: 15px;
     margin-right: 10px;
     margin-bottom: 15px;
     margin-left: 10px;
}

label {
       display: inline-block;                  /* necesario para alinear el texto */
       vertical-align: middle;
       width: 100px;
       height: 25px;
       padding: 5px;
       text-align: right;
}

input {
      width: 200px;
      height: 25px;
      padding: 5px;                           /* add space inside the text field */
      border: 1px solid blue;
      border-radius: 4px;                     /* esquinas redondeadas */
}

#btn {
        visibility: hidden;
}

#boton {
        height: 25px;
        width: 212px;
}

</style>