CSS not updating, and file permissions question

Hi everyone.

I am working on a pre-existing www.remarpro.com site for my client, which was set up and customized by someone else.

I have been attempting to make changes to the site’s CSS and layout (including the page.php file) but none of my alterations are taking effect. I can’t via the WordPress dashboard; it says that I “need to make this file writable before you can save your changes.”

Since I didn’t install this version of WordPress, I don’t know what to do with the permissions. For example, the page.php file is set to 644; do I need to change this?

I’ve tried editing the files via the site host’s cPanel, but none of those changes seem to take effect either. I have cleared my browser cache as well as tried it on several different computers, and the changes were made almost 24 hours ago but have not shown up. There are no caching plugins installed on the site, either.

Any help would be greatly appreciated!