I've noticed some wordpress themes have these vertical and horizontal lines that do an effective job of organizing the content of the blog. There's usually 1 long vertical line that separates the main content from the sidebar content. And then there's several vertical and horizontal lines in the sidebar itself to separate things such as banners, social media icons, and the blogroll.
How do I create these lines and where do I add the code? I've looked at several wordpress themes with these designs, but can never find the code they use in the CSS. I want a line that separates the main content from the right sidebar. and several horizontal lines in the sidebar. Any help would be appreciated.
Here are example themes from wordpress where lines are used for organization: