Your .htaccess should not be modified on the WordPress part, so it should always be:
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
It looks like if you have your WordPress install in a Subdirectory of the folder you map your domain to. In this case, you will have to do the following:
Copy your WordPress index.php into the root directory, and change the path of require('./wp-blog-header.php'); to use your directory instead. Should be like this:
<?php
/**
* Front to the WordPress application. This file doesn't do anything, but loads
* wp-blog-header.php which does and tells WordPress to load the theme.
*
* @package WordPress
*/
/**
* Tells WordPress to load the WordPress theme and output it.
*
* @var bool
*/
define('WP_USE_THEMES', true);
/** Loads the WordPress Environment and Template */
require('./wordpress_1/wp-blog-header.php');
You may also need to copy your .htaccess into this directory.
In your WordPress Settings you have to change the option WordPress URL to http://yourdomain.com/wordpress_1 while leaving the option Siteurl at http://yourdomain.com/.
This should do the trick for your Styles and Performance!