(heavily) edited 'Quark' theme posing me some probs

So; it's So . . . I've modified things beyond my own recognition, and--while I am 97% of the way "There"--many, many questions remain.

My website blog:

http://andyrew.info/blog/

I have spent a great deal of time creating a mod of the "Quark" theme, as it is:

a) entirely stupendous, and

b) allows a Sidebar (which, of course, allows much, much more info to be displayed on one's Main).

In doing-so, I have the partials/taxonomy.html.twig in my sidebar, and it functions as I have expected (e.g., Popular Tags > "HAIKU" (click-->)) gets me to "http://andyrew.info/blog/tag:haiku", which subsequently lists every blog item.md with a 'haiku' tag....

Alas, when I select an individual @self.child item (and I am in the 'space' of that individual psot), my taxonomy 'tag' list links me to "http://andyrew.info/tag:haiku"; which (of-course), takes me to my bespoke 404 error page ;(

I know this kind of event(uality) has happened, to someone, once, if not more, before.

It is my wish that I may I draw on the experience of others more knowledgeable in these matters, that I gain understanding . . .

. . . is there anyone here who might help me?

If you need additional code/photos/print, I can make this possible.

Thank you.

Regards, andyrew

So, it turns-out that line 27 of the stock Quark templates/partials/sidebar.html.twig reads as follows:

{% include 'partials/taxonomylist.html.twig' with {'base_url':new_base_url, 'taxonomy':'tag'} %}  

changing that to:

{% include 'partials/taxonomylist.html.twig' with {'base_url':base_url, 'taxonomy':'tag'} %}  

Gives me the proper (for example):

http://andyrew.info/blog/tag:haiku

lines1/2 read:

1 {% set feed_url = blog.url == '/' or blog.url == base_url_relative ? (base_url_relative~'/'~blog.slug) : blog.url %}
2 {% set new_base_url = blog.url == '/' ? '' : blog.url %}

blog.url is null in my config, which is (I guess) why my new_base_url is null...

Regards, Andrew