DirectoryIndex index.html index.htm index.php
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.html$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.html [L]
ErrorDocument 403 /index.html
ErrorDocument 404 /index.html
</IfModule>