Hi there,
This is possible with CSS, but not simple – you’d have to change several different things in order to do this, and it’s more complex than what we provide support for with our themes.
I’m not even sure what exactly you want to have wider, though – on my screen your site takes up just about the full width of the screen – the margins are only around 3cm on each side, which just frames the content nicely. Making your content any wider, and those margins any narrower, will just make the site look bad if you ask me.
And if so (maybe if style.css is edited) would there be downsides to doing so
It is never a good idea to modify any file on your site directly – if you edit the theme’s style.css file and the theme gets updated, your modified file will be replaced and your changes lost. In a case where you need to modify a file for a customization (which is not needed if you just want to add some CSS, as you can do that from the Cusotmizer), the best practice is to create a child theme.
given that every visitor to the site will have varying screen widths?
This is a separate issue from modifying theme files directly, so let me answer it separately.
Your theme as it currently stands is designed to automatically adjust its layout based on the size screen your site is being viewed on. Any custom CSS you add to modify your site, likewise need to take different screen sizes into account, which just adds to the complexity of the code needed for the type of change you want to make.
But in this case I wouldn’t recommend trying to make the site content any wider.
