Override the blogPost default.htm

To override the blogPost (single post) default template default.htm you create in the theme folder
in the folder partials a new subfolder named blogPost.

In this subfolder you place a new file named default.htm.

To make life a little less complicated you can copy the contents from the file plugins\rainlab\blog\components\post\default.htm and modify this to your own requirements.

original content

{% set post = __SELF__.post %}

<div class="content">{{ post.content_html|raw }}</div>

{% if post.featured_images.count %}
    <div class="featured-images text-center">
        {% for image in post.featured_images %}
            <p>
                <img
                    data-src="{{ image.filename }}"
                    src="{{ image.path }}"
                    alt="{{ image.description }}"
                    style="max-width: 100%" />
            </p>
        {% endfor %}
    </div>
{% endif %}

<p class="info">
    Posted
    {% if post.categories.count %} in
        {% for category in post.categories %}
            <a href="{{ category.url }}">{{ category.name }}</a>{% if not loop.last %}, {% endif %}
        {% endfor %}
    {% endif %}
    on {{ post.published_at|date('M d, Y') }}
</p>