Temporarily modifying CSS of an HTML page using PHP script
I am working on a website where a user types in a domain name and the html page goes into a php page to check it's availability. The page needs to go to the next html page if the domain is available but if the domain is taken, it needs to return to the first html page and modify the css to reveal a piece of hidden HTML code displaying that the url is taken. 

What kind of php code do I need to add to my php file, so that when the script come up with a false (domain is taken) it will shoot the browser to the form.html and change the css to display the html div tag that was originally hidden without making the change permanent.

Also, if there is an better way to change the page without touching the css and html (ie. jQuery), then please let me know.

I am a complete noob when it comes to php so I don't even know how to search for this. Sorry if this question has not been answered but I did not even know how to search for this and when I google'ed the title I got nothing close to what I was searching. 

Thanks!
Temporarily modifying CSS of an HTML page using PHP script
===

I am working on a website where a user types in a domain name and the html page goes into a php page to check it's availability. The page needs to go to the next html page if the domain is available but if the domain is taken, it needs to return to the first html page and modify the css to reveal a piece of hidden HTML code displaying that the url is taken. 

What kind of php code do I need to add to my php file, so that when the script come up with a false (domain is taken) it will shoot the browser to the form.html and change the css to display the html div tag that was originally hidden without making the change permanent.

Also, if there is an better way to change the page without touching the css and html (ie. jQuery), then please let me know.

I am a complete noob when it comes to php so I don't even know how to search for this. Sorry if this question has not been answered but I did not even know how to search for this and when I google'ed the title I got nothing close to what I was searching. 

Thanks!