Hi Bletek,
Please double that value, (because of retina display) it was intended to divide the value by 2, so 350px / 2 you get 175px.
Your Topbar is already filled with a semi-transparent black background.
Please check your entire custom CSS here and address all found errors. Those syntax errors can mess up the other CSS blocks.
Yes, it always does. We advise our users to always update the Wordpress to the latest versions. You’ll get in trouble not only with themes but plugins too if you keep your Wordpress outdated.
Updating WordPress
If you feel uneasy updating, please keep a back up of your entire site. Or clone your site to a staging server and do your updating there first, so you can tackle issues that may occur while keeping your live site untouched.
Remember to clear all your caching features (plugin, server-side, CDN, and browser’s cache) after updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.
Let us know how it goes,
Cheers!