I am using Sitecore wffm forms on web page. I needed to use a custom CSS file for the form, so I am following https://sitecoregenie.wordpress.com/2018/08/06/add-a-custom-css-file-for-wffm/ to add custom CSS file for the form and for doing that new CSS file should be added in folder
\sitecore modules\Shell\Web Forms for Marketers\Themes\.
Now, when I navigate to the web page to see Sitecore WFFM form, the custom CSS file is not applied to the web page. When I go to view source of the page, I see that the CSS file is being added but when I click on it I am being navigated to the Sitecore login page. Is there a way to bypass the Sitecore login for that CSS file in the Sitecore modules folder so that the page loads the CSS file and applies it to my form?