Можно обернуть элементы формы Contact Form 7 в bootstrap как то так:
<div class="row">
<div class="col-md-12 form-group text-white">* - поля, обязательные для заполнения</div>
</div>
<div class="row">
<div class="col-md-4 form-group"><label class="sr-only">Имя</label><span class="placeholder">Имя</span>[text* your-name class:form-control]</div>
<div class="col-md-4 form-group"><label class="sr-only">Телефон</label><span class="placeholder">Телефон*</span>[text* your-phone class:form-control]</div>
<div class="col-md-4 form-group"><label class="sr-only">Email</label><span class="placeholder">Email*</span>[email* your-email class:form-control]</div>
</div>
<div class="form-group"><label class="sr-only">Тема</label><span class="placeholder">Тема</span>[text your-subject class:form-control ]</div>
<div class="form-group"><label class="sr-only">Сообщение</label><span class="placeholder">Сообщение</span>[textarea your-message x5 class:form-control]</div>
<div class="row">
<div class="col-md-6 form-group">[quiz quiz-413 class:form-control "1+1=?|2" "2+2=?|4" "3+3=?|6" "4+4=?|8" "5+5=?|10"]</div>
<div class="col-md-6 form-group">[submit class:btn class:btn-primary "Отправить"]</div>
</div>
