I have the following code.
form {
  outline: 3px solid blue;
  width: 50px;
  /* why doesn't it hold? */
}
.container {
  border: 2px solid green;
}
code {
  display: block;
  overflow: auto;
  white-space: pre;
}<form>
  <fieldset class="container">
    <code>
<some>
 <very>
  <looooooooooooooooooooooooong>
   <html>
    <code>
   <here which="should break in multiple lines, or be scrollable">
    </code>
  </fieldset>
</form>The problem is, that the <fieldset> seems to adapt the width from the <code> element inside, instead of the outer <form>. The green box should be contained inside the blue box, and the code should be scrollable.
But instead, the green box blasts out of the blue box:

How can I make the <code> adapt the width from the <fieldset> which should adapt its width from the <form>?
 
    