Most recent version of reCAPTCHA / V2 (4.5.1) works just fine on Windows Phone 8.1 for us.
.rc-anchor-normal appears to be the CSS to control the width. We don't use a responsive design on our shop (for a number of reasons) so I didn't bother testing it, but changing the value of that with inspect element tool seems to work.
I'd definitely test it to make sure it still works after modifying.
I thought it's small enough, so there is no need to make it resposive. For me it's 300px width, the outer container is a IFrame with 304px width (html coded). So for a bootstrap theme with 15px margin it has some pixels overflow, but is in view. I have no clue how to control this...
I uploaded to my production site so i could see it on my droid maxx and it fits just fine. Anything smaller than a 5" screen may have issues but who nowadays has a smaller screen LOL.
I was able to change the size of the iframe but all it does is shrink the iframe not the contents within. The recaptcha logo got cut off. Google probably wouldn't like that. So i guess it works for me.
I did everything that gyn told but it did not work for me, I also should mention that I did not have Captcha folder under UI It was under Security folder. what I might did wrong?
Yes, in 3.6 this Captcha Folder has moved to the Security folder. I have compared the two files between 3.5 and 3.6 and they are the same except the namespace: In 3.5: namespace Nop.Web.Framework.UI.Captcha In 3.6: namespace Nop.Web.Framework.Security.Captcha