I am working now on a website and of course I am using one general CSS template for the whole website. Now, I am adopting one ready-design (sign up) from the internet, but the problem with it has its own CSS template, so when I tried to add it to my website with its own assets including images and CSS, it messed the general the appearance of my website. I tried to modify or include the secondary CSS inside the website's CSS file but I failed.
So what is the proper solution to this problem? How can I fix it?
Thanks, matrix388