Why are there differences between Jekyll on local server and github?

Thanks. This is my (source) directory structure

.
├── 404.html
├── about.markdown
├── _config.yml
├── Gemfile
├── Gemfile.lock
├── index.md
├── _posts
│   ├── A2020-03-23-welcome-to-jekyll.markdown
├── _site
│   ├── 404.html
│   ├── about
└── wx_python
    ├── images
    │   ├── basic_frame.png
    ├── introduction.md
    ├── post01.md
    ├── post02.md
    ├── post03.md
    ├── post04.md
    ├── snippets
    │   ├── basic_frame.py
    └── wxpython_from_scratch.md

In my _config.yml

baseurl: "/psionman_set" # the subpath of your site, e.g. /blog

To access an image I use the code

![](/wx_python/images/basic_frame.png)

It allows me download a snippet using the code

([raw\_frame.py](snippets/basic_frame.py))

This is at a similar place in the directory tree.

How do I need to change this?

A typical page is at https://psionman.github.io/psionman_set/wx_python/introduction.html

The menu-bar is a list of pages which it has picked up from the header in each page: typically

## WxPython from Scratch

The header is also duplicated on the displayed page

this is what it should look like