   <label for="username">Username</label>
              <div class="input-group">
                <div class="input-group-prepend">
                  <span class="input-group-text">@</span>
                </div>
                <input type="text" class="form-control" id="username" placeholder="Username" required>
                <div class="invalid-feedback" style="width: 100%;">
                  Your username is required.
                </div>
              </div>
            </div>

            <div cl