Broadly speaking…

In Wordpress blogs are not permitted under the horizontal lines (horizontal rule) that have been very helpful in the HTML of a lifetime to organize and structure a page. What inhibits these lines we have in the CSS wordpress. Here we find the following code:

HR (
display: none;
)

This simply means that when writing a line, either by editing HTML or by Tiny or some other WYSIWYG editor, does not appear.

To fix this, if you want to put any lines to separate concepts or whatever, you can simply delete this piece of code, or write the best line in another way:

<hr /> style="display:block;"
with what that line in particular it will be represented.