Categories, Display Multiple with a | between categories

Use the wp_list_categories function, to display with a | between categories
So for this post -
would be: Marathon | Running

Does the require single.php, or function.php or the css to be edited?

Worked out a solution by editing the css:
nav li:last-child .pipe {
display: none;
} li + li:before{
content: " | ";

Hey there,

I hope you’re doing well today

We would have recommend CSS, but you figured it out on your own.
And a very neat fix at that too. Thank you for sharing it with us.

Best Regards,