In a number of our webpages we use the "read-more"-feature. In Category Blog display such pages are shown with their content up to the "read-more"-label. If you push the "read-more"-button, then you get the whole page. Up to now everything normal.
But from the "read-more"-position onwards the text is shown with an indent of 25% of the page width (indent on the left side).
Upon inspection of the HTML-code of such a page, I was able to find the piece of code that causes this behaviour.

<div class="container">
<div class="bottom-article-info">
<div class="article-inner">
<div class="row">
<div class="col-12 col-md-3 order-2 order-md-1 mt-5 mt-md-0">
<div class="siderbar-article">
</div>
</div>
<div class="col-12 col-md-9 order-1 order-md-2">
<div itemprop="articleBody" class="article-body">_

In particular the classes col-md-3 and col-md-9 cause this behaviour. The first one taking 3 of the 12 pieces of a row (25%) and the second one taking the remaining 75%.
I do NOT want this behaviour. But I haven't found where this is caused and how I can prevent this.
In the end I solved the issue by redefining the classes col-md-3 and col-md-9. I know this is BAD BEHAVIOUR!

Note: when I looked at the page (before applying the changes above), I also saw that at "read-more"-position in the text, the css-position "read-next" is introduced. Probably there is a relation between the introduction of this position and the indenting behaviour.
I added a picture of it.

Can anyone tell me if there is another (non-destructive) way in order to get rid of this indent-behaviour?

Kind greetings,

Hendrik