Editor mode - change tags?

Have a look here →

Tags in Editing view (source and live preview) have three parts: The main section for background, text color, etc., and then the beginning & end for paddings and borders.

For example, here Reading and Editing view tags are separated:

/*---- reading view tag ----*/
.tag[href="#Google"] {
    background: #fff;
    color: #176bef;
    border: 2px solid #176bef;
    line-height: 2em;
    font-weight: 500;
    padding-top: 1.5px;
    padding-bottom: 3px;
}

/*---- source + live preview tag ----*/
.markdown-source-view .cm-tag-Google {
  background: #fff;
  color: #176bef;
  border-top: 2px solid;
  border-bottom: 2px solid;
  line-height: 2em;
  font-weight: 500;
}

.markdown-source-view .cm-hashtag-begin.cm-tag-Google {
  border-left: 2px solid;
  padding-top: 1px;
  padding-right: 1px;
  padding-bottom: 3.5px;
}

.markdown-source-view .cm-hashtag-end.cm-tag-Google {
  border-right: 2px solid;
  padding-top: 1px;
  padding-bottom: 3.5px;
}

Screenshot 2023-11-14 at 5.09.04