Text fields get rendered like this:
<input class="form-control form-text required" type="text" id="edit-submitted-name" name="submitted[name]" value="" size="60" maxlength="128">
Webform will output the following code for email fields:
<input class="email form-text form-email required" type="email" id="edit-submitted-e-mail" name="submitted[e_mail]" size="60">
Notice “form-control” missing from the email field. This is due to how the Bootstrap theme rewrites form fields.
This module lets you add the required class so the output looks like the following without having to add any custom styles: