When copying a text or sentence from internet or another document, make sure to select "Pasted as plain text instead" - this will clear all the formats from the previous document and allow the editor to easily manipulate the text.

Many document editors fail to check the responsive design of their work and are left with visual errors where the content does not look good on a mobile device.

On many supported browsers, pressing F12 will allow editors to change the responsive characteristics of the page.