.tc-editor-toolbar {
position:sticky;
position: -webkit-sticky;
position: sticky;
top: 45px; /* distance to stick from top, e.g if you use top bar */
left:0;
width:100%;
font-size:.90em;
padding:0;
border:5px solid transparent;
background: white;
z-index: 1;
}
This causes the editor tool bar to scroll down the page, may answer your source problem because it seems to have a bug when using preview causes the edit and preview to scroll together and the editor tool bar does not move.
My Problem may be your solution :)
Tony