使用默认成员资格时添加自定义登录表单

I am using the Default Membership Provider that ASP 4.5 WebForms uses (using my own database) and I am facing a problem regarding the login form. I want to make a custom one because I am using a fancy CSS/HTML5 code for it, but using the default control given my Visual Studio just breaks it, and I want to execute some custom code on the login press while also maintaining the controls that Default Membership Provider already brings (like Password Failure count, etc). What method/process should I call or what custom code should I write so that when the user writes the username and password it uses the values of those textboxes for login purposes? I tried dabbling into the Login button of the Login controller but its too limited in scope and the tables still break a bit the design. Any help is greatly appreciated!I am using the Default Membership Provider that