How to remove this?

From all pages and posts.

Can you provide links to two pages with the lines, two occurrences?

Images really don’t help with CSS questions. As Andrew pointed out can you provide a link?

Generically speaking:

Create a child theme of Twenty Twelve and use a CSS tool such as Firebug or Chrome’s built-in inspection tool to identify what’s causing those lines.

Once you have identified the CSS then you can adjust it in your child theme.

It appears on all post pages.

Tried with firebug but I can not find it.

Is it these horizontal lines you want gone https://awesomescreenshot.com/0c3r5lua8 ?

Yes Andrew.

I want to remove these “horizontal lines”

Try this CSS;

.site-content article {
 border-bottom: 0;
}

Andrew,

You sir are amazing.

Nasty lines gone.

Thanks so much.

And Thanks Simmeon (and Jan) for contributing to the open-source community.

I have the same question and have tried the same solution but found it didn’t have any effect, and I am confused as to why. I have created a child theme and copied the CSS given above into it, but no luck. Also tried to inspect the element using FF Web Developer and had a deal of trouble isolating it, since it appears in so many IDs. Any thoughts would be appreciated.

@william_kowalski – please start your own thread per the forum guidelines – this one is marked resolved. You also MUST post a link to your site for CSS questions.