Your actual _layouts/post.html layout as layout as layout...
In fact it's a layout problem.
Actually your layout layout doesn't load your script.
Change front matter for layout: "default"
and deleted include header
and include footer
.
Your layout layout now reads like this :
---
layout: default
---
<article class="article">
<section class="article-cover">
<img class="header-image" src="{{ page.headerImage }}" alt="{{ page.headerAlt }}">
<span>
<h3 class="post-id">{{ page.postId }}:</h3>
<h1 class="post-title">{{ page.title }}</h1>
<h4 class="post-date">{{ page.date | date: "%Y.%m.%d" }}</h4>
</span>
</section>
<div class="content-wrapper">
<section class="article-body center" itemprop="articleBody">
{{ content }}
</section>
</div>
</article>
{% if page.next %}
{% assign next = page.next %}
{% endif %}
{% if page.previous %}
{% assign previous = page.previous %}
{% endif %}
<div class="next-previous">
<ul class="adjacent-list">
{% if page.next %}
<li>
<a class="post-link" href="{{ next.url | absolute_url }}">
<div class="post-summary"
style="background-image: url({{ next.headerImage }}); background-position: center; opacity: .7;">
<div class="title-container">
<h3 >{{ next.postId }}:</h3>
<h1>{{ next.title }}</h1>
</div>
</div>
</a>
</li>
{% endif %}
{% if page.previous %}
<li>
<a class="post-link" href="{{ previous.url | absolute_url }}">
<div class="post-summary"
style="background-image: url({{ previous.headerImage }}); background-position: center; opacity: .7;">
<div class="title-container">
<h3 >{{ previous.postId }}:</h3>
<h1>{{ previous.title }}</h1>
</div>
</div>
</a>
</li>
{% endif %}
</ul>
</div>