Printing a page using printable.module - rendering error

Problem/Motivation

I am trying out the printing of a page using printable.module. However the text

li {
display: inline;
margin-right: 5px;
}
is printed above the widget and "Print". This text - obviously css - isn't enclosed in any

markup. Thus it simply gets printed as is...

Looking into the matter, I find that (in MY case) this is an issue within printable.module. In function pintable_entity_view(...) lines 223 ff. look like this:

$build['printable_navigation'] = [
'#markup' => '

',
'#attached' => [
'library' => ['printable/entity-links'],
],
'#weight' => 100,
'#cache' => [
'tags' => $entity->getEntityType()->getListCacheTags(),
],
];
It seems to me that maybe the variable $printable_navigation doesn't contain the right markup.

Steps to reproduce

Install and activate the printable module and select some node type

Proposed resolution

enclose the "li {...} specification within

Remaining tasks

User interface changes

API changes

Data model changes