Change second level vertical menu to horizontal menu

Do not edit the Twenty Thirteen theme. It is the current default WordPress theme and having access to an original, unedited, copy of the theme is vital in many situations. First create a child theme for your changes.

Hello Esmi,

thanks for you answer, I created a child theme, but how can I change the menu from vertical to horizontal now.

Thanks,
Chris

You need to move all of your previous customisations – including the CSS changes – over to your child theme.

Okay thanks, I activated the child and put the customized menu in it.
Is there something more?
Is there a easy way to customize the second level menu?

Thanks,
Chris

No, you need to put all of your changes in the child theme. Then re-upload a fresh, unpacked, copy of the Twenty Thirteen folder to wp-content/themes using FTP or whatever file management application your host provides.
https://www.ads-software.com/themes/twentythirteen

Hello, okay so I should remove the old theme o Twenty Thirteen and upload a new one.
What should I do afterwards?

Thanks,
Chris

so I should remove the old theme o Twenty Thirteen and upload a new one.

Yes but do make sure that you’ve saved all of your customisations first.

What should I do afterwards?

Have you added all of your changes to your child theme?

Thx, I tried to save everything, but how can I do that?
Do I have to write everything by hand within the style.css?

It′s css so what should i do with php,…

Thx,
Chris

I also added some code to the content or customized the topic within the header.php
Is it allowed to customize it within the php files or do I loose this information?

Thanks for helping,
Chris

Is it allowed to customize it within the php files or do I loose this information?

You should never edit any of the file in a WPORG theme – especially when it is the default WordPress theme. Having access to an original, unedited, copy of the theme is vital in many situations. All of your changes will be lost when you update the theme.

Okay thanks, I got it now.
I have had an plugin for extra widges. It told me I should add a php code within the wanted direction, so I could intall widgets. Therefore I thought it′s okay.

Anyway, I still try to change my submenu from vertical to horizontal.
Is there a plugin to change that? Or do I have to do it somehow manually within the child style.css?

You need to make the change manually via the child’s CSS.

Okay thanks, I do not have any idea how to do it.
Probably I have luck somehow.

Try adding this to your Child Theme style.css file (right at the bottom):

.nav-menu li { position: initial; }

Isn’t that only supported by the web-kit browsers atm?