.htacces Appears only html with no CSS or PHP -

i've been wondering on internet on how work htacces(really hard learn it). , when lurking in internet, found this: http://www.generateit.net/mod-rewrite/

well, inserted url(working on localhost):
empresa.com/index.php?p=sub_artigo&id=1&cat=mercearia

and gave me this(with options default):
http://empresa.com/sub_artigo/5/mercearia.html

and .htacces code this:
rewriterule ^([^/]*)/([^/]*)/([^/]*)\.html$ /index.php?p=$1&id=$2&cat=$3 [l]

and when generate url in php do

<a href=\"sub_artigo/".$response2['id_sub_artigo']."/".$response2['url'].".html\">$response2[nome_sub_artigo]</a> 

and then, when click button, appears like, html. example: http://s14.postimg.org/wr137fx4x/htacces_error.jpg

any idea happening ?

it looks using relative links assets (images, javascript, css).

that means when css/my_stylesheet.css, new url, browser request url http://empresa.com/sub_artigo/5/css/my_stylesheet.css.

the easiest solution use absolute urls assets, /css/my_stylesheet.css, etc.