Fix contact form

Author: vincent-pochet

index.html

@@ -484,8 +484,8 @@ <h2 class="section__title" data-lang="fr">Contactez-nous</h2>
           </div>
 
           <input type="hidden" name="return_url" value="https://www.ruby42.com/#contact" />
-          <button type="submit" name="commit" class="btn" data-lang="en">Send Message</button>
-          <button type="submit" name="commit" class="btn" data-lang="fr">Envoyer le message</button>
+          <input type="submit" name="commit" class="btn" data-lang="en" value="Send Message" />
+          <input type="submit" name="commit" class="btn" data-lang="fr" value="Envoyer le message" />
         </form>
       </div>
     </section>