Simple_form text boxes are extremely long - ruby-on-rails

Question

Using simple_form and bootstrap, and I'm having trouble getting the input boxes to size correctly. They're different, overly long, lengths. I can hardcode them in the CSS, but then they're non-responsive. (I tried max-width, but they end up a fixed width.) Also using the devise gem for user authentication.
Page Code:
<div class="booyah-box col-xs-10 col-xs-offset-1">
<h2>Sign up</h2>
<%= simple_form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f| %>
<%= f.error_notification %>
<div class="form-inputs">
<%= f.input :email, required: true, autofocus: true %>
<%= f.input :password, required: true, hint: ("#{#minimum_password_length} characters minimum" if #validatable) %>
<%= f.input :password_confirmation, required: true %>
</div>
<div class="form-actions">
<%= f.button :submit, "Sign in", :class => 'btn btn-primary' %>
</div>
<% end %>
<%= render "devise/shared/links" %>
</div>

Answer 1

<div class="row">
<h2>Sign up</h2>
<div class="col-lg-8 col-md-4 col-sm-12 col-xs-12">
<%= simple_form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f| %>
<%= f.error_notification %>
<div class="form-group">
<%= f.input :email, required: true, autofocus: true, class: "form-control" %>
// you can add class **col-lg-6** in any input field for maintaining the width
<%= f.input :password, required: true, hint: ("#{#minimum_password_length} characters minimum" if #validatable), class: "form-control" %>
<%= f.input :password_confirmation, required: true, class: "form-control" %>
</div>
<div class="form-group">
<%= f.button :submit, "Sign in", :class => 'btn btn-primary' %>
</div>
<% end %>
<%= render "devise/shared/links" %>
</div>
</div>