.htaccess filepaths differing how to solve - php

Question

I've made www.site.com/asd to redirect to www.site.com/index.php?page=asd. However, I would like to add one more thing, where www.site.com/products/asd would redirect to www.site.com/index.php?page=products&item=asd
I can't seem to get it working, I have this as my base code:
RewriteEngine On
RewriteRule ^(admin|pictures)($|/) - [L]
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
RewriteCond %{REQUEST_URI} !=/pictures/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ /index.php?page=$1 [L,QSA]
I've tried adding:
RewriteRule ^([^/]*)/([^/]*)$ /index.php?page=$1&item=$2 [L]
in various locations of the .htaccess file, which either results in:
500 Internal Server Error
or
0 CSS files load in .com/products/asd And no pictures load in .com/anyfile
I understand it's path related, but is this a good way to go about it? Can I solve it somehow in the .htaccess file, or would I need to add some check that if it's product page and a product is shown, include ../css?

Answer 1

The ^(.+)$ regular expression gives you a "500 Internal Server Error" because the redirection matches to the rule. So you gets the following error:
Request exceeded the limit of 10 internal redirects due to probable configuration error.
You can use:
RewriteRule ^products/(.+)$ index.php?page=products&item=$1 [L,QSA]
RewriteRule ^([^\.]+) index.php?page=$1 [L,QSA]
So, the following URLs will be redirected to:
/products/asd to index.php?page=products&item=asd
/asd to index.php?page=asc

Answer 2

Change the last two lines like this :
RewriteRule ^([^/]+)/?$ /index.php?page=$1 [L]
RewriteRule ^([^/]+)/([^/]+)/?$ /index.php?page=$1&item=$2 [L]
You should specify that in first rule a URI must come like /whatever/ or /whatever so the second will match either /whatever/whetever or /whatever/whatever/ and both will work individually without any interference.