Prevent Angular Summernote from Stretching

Question

In my application, I use angular summernote with a bootstrap modal window as follows:

<div class="form-group">
  <div class="col-sm-12">
    <label for="input-m-1">Bio</label>
    <summernote ng-model="model.bio"></summernote>
    <p>The maximum length of 250 characters.</p>
  </div><!-- col -->
</div><!-- form-group -->

Everything seems to work just fine, except for one problem: if I keep typing in the summernote area without pressing Enter, then it extends beyond my modal.

The official documentation says nothing about preventing this. Maybe someone had this problem or I had any ideas what I can do about it?