Validation breaks styling of bootstrap form control class

I have a webform that is using bootstrap3. My textbox is using the form-control class. Here is the control:

<asp:TextBox ID="txtEmail1" runat="server" CssClass="form-control" PlaceHolder="Email"></asp:TextBox>&nbsp;&nbsp;&nbsp; <asp:Button ID="btnNext" runat="server" CssClass="btn btn-success" Text="Next" OnClick="btnNext_Click" /> <asp:RequiredFieldValidator ID="rfvEmail" runat="server" CssClass="form-control" ErrorMessage="Email is required" ControlToValidate="txtEmail1" BorderStyle="None" CssClass="required"></asp:RequiredFieldValidator> <asp:RegularExpressionValidator ID="refEmail" runat="server" CssClass="required ...