Center footer column content

Example:

Code:

/* -- code to center footer column content -- */
.site-footer-wrapper { text-align: center; }
/* - end - */

Code for mobile only: 

/* -- code to center footer elements on mobile only -- */
@include at-query($max, $small) {
.site-footer-wrapper { text-align: center; }
  }
}
/* - end - */

The first code snippet will center the footer elements for all browsers and devices. The second will only center the content on mobile devices.

Where do I add the code?

Open your Code Editor. 

From your list of themes, find the Actions link for the theme you'd like to edit. Then select Edit code. Example draft theme:

Example if you're working from your main live/published theme:

Quick link if the theme is live/published:
Open Code Editor

Next, in the Code Editor find your theme's CSS file, this will vary depending on which version of Pipeline you're running:
Which version of Pipeline am I using?

Once you know your version, find the right file in the left Assets folder:

Pipeline 4 - If you're working with a draft theme, open this file:

You'll be opening this file:

assets/theme.scss.liquid

Quick link if the theme is live/published:
assets/theme.scss.liquid

Earlier versions of Pipeline - If your theme is older than Pipeline 4 open this file for draft themes:

You'll be opening this file for earlier versions of Pipeline:

assets/style.scss.liquid

Quick link if the theme is live/published and an earlier version of Pipeline:
assets/style.scss.liquid

Add the code to the very bottom of the file on a new line. Make a couple blank lines before pasting the code snippet. 

Save the file after adding your code.