URL rewriting : css, js, and images not loading
one solution is that use absolute path (ex /css, or /js rather than just css/, /js but this is not looks a reliable solution since we've to change it on all files,
This is because your relative URIs have their base changed. Originally, the base is / when the page is /detail.php?id=123, and the browser properly fills in relative links with the / base. But when the browser goes to a page like /detail/123 the base suddenly becomes /detail/ and it tries to append that in front of all relative URLs and thus none of them load.
You can either make your links absolute, or change the URI base in the header of your pages (inbetween the <head> </head> tags):
<base href="/">
Don't be lazy and change your relative URIs in your resources to root directory absolute pathing like /css/style.css. This is the best.
You can get clever and use regex and replace all the files you need which would be like a few one liners and you're done. How many places could there be to change? And you should be using a template.
This should work but I wouldn't go this way.
RewriteRule ^detail/(css|js|img)/(.*)?$ /$1/$2 [L,QSA,R=301]