  <input class="form-control input-dark" type="text" placeholder="Dark"/>
                  </div>
                  <div class="form-group">
                    <input class="form-control input-dark is-valid" type="text" placeholder="Valid"/>
                  </div>
                  <input class="form-control input-dark is-invalid" type="text" placeholder="Invalid"/>
                </div>
                <div class="card-footer">
                  <pre class="pre-scrollable"><code class="language-markup