Yes, if you want the exact same styling for most posts you'll do most of it in the CSS editor: it's better and easier.
You'll give this type of div a name, for instance "telaio".
You'll transfer all the styling to the CSS editor:
border: 3px double #444444;
Then in the post editor you'll only write this:
Note: I changed the border color to the dark grey of the theme (in your example you used the same color for border and bg, so the border won't show). Also, double border means two lines with white space between them, so it cannot be 1px: I changed it to 3px. If you prefer a single thin line, use this in the above code:
border: 1px solid #444444;