Insert a splash page

Just curious how I can insert a splash page without wordpress stepping in the way and directing to index.php.

I suppose ‘splash’ is a bad term… I’m just more interested in an ‘under construction’ page up front while I work out the kinks in my CSS design… it’s purely temporary.

I have index.htm (the splash) in the root directory right now. I tried to use a .htaccess file code… but failed, here’s what I used:

#DirectoryIndex index.php index.html
#Options +FollowSymLinks
RewriteBase /

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^(.+) – [PT,L]

RewriteRule ^(.*) index.htm
</IfModule>