Answer 1

Modern text editors (I hope you don't use Notepad) have multiple tabs to open. Create and open in a tab the html file and then create and open in another tab, next to first, the css file. To move between you can use Ctrl-Tab as a shortcut. You add the css file like that <link rel="stylesheet" type="text/css" src="filename.css">. It's better than using <style> tag in the html file.