Resolve bugs through learning and example for htaccess and JS

Resolve some bugs for php based project as the title suggest and the explanation of the problem are found in the attached files. HOWEVER PLEASE TAKE NOTE OF THE FOLLOWING: The link to my codes is not available hence you won't be able to access my codes to resolve the problems . But it's not necessary because For the first part , what happened is it seems that it's due to class conflict between the existing bootstrap class and this new one that I have described. Therefore to resolve you can use Teamviewer and SHOW ME in your system how to identify classes within such bootstrap and how to resolve such similar conflict, using whatever tools and browsers wizards to find that conflict. For the second part of htaccess issue , as you have seen that this htaccess is supposed to mask the extension as well as if anyone tries to put in an extension to the URL as a test or decoy then we will just show as page not found, so again please show in your system using the corrected htaccess to show the desired effects.