[Theme Rookie] Remove sidebar > Post full width

Add this to your custom CSS:

#secondary {
    display: none;
}

#primary {
    display: 100%;
}

#secondary display:none removes the sidebar. And then #primary display:100% extends the width of the content area from 66% to 100%.

I don’t have a custom CSS file ??

Not a problem. If your theme didn’t come with an area for custom CSS, then we can just create it. You’ve got 2 options:

Option 1: If you’re unfamiliar with coding, you can go the easy way: use a Custom CSS plugin.

1. Install Simple Custom CSS plugin https://www.ads-software.com/plugins/simple-custom-css/ and activate it,
2. In your WordPress Dashboard, go to Appearance –> Custom CSS,
3. Copy-paste the code that I’ve provided there, and save it.

Option 2: If you’re familiar with some basic coding, you can create a child-theme and play around with it there. Here’s the instruction: https://codex.www.ads-software.com/Child_Themes

The site does not like me.

Now i have this problem. https://isg-net.dk/

That’s 500 internal server error is not an issue related to CSS because all CSS does is prettify whatever the browser displays on your site.

It’s related to one of the site configuration or .php file. Just take whatever configuration or .php file that you’ve edited last and restore it to the original state.