How to make different master pages via .htaccess?

Question

htaccess

It is necessary to make it so that those who come to the site from mobile devices are redirected to the static mobile.html page (there is), but at the same time, they have the opportunity to continue walking on the main site that is under wordpress.
I tried to implement it via htaccess like this:

RewriteEngine on 
RewriteCond %{HTTP_USER_AGENT} iphone|ipad|android|blackberry [NC] 
RewriteRule ^index\.php$ /mobile.html

but then all requests to other pages from a mobile phone like ?page_id=49 also refer to mobile.html and, accordingly, no other page is opened. It is necessary that index.php processes
them