how i trifle divs controlling wholly css?

given template where html can't run-down since requirements, illusory arrangement (rearrange) div above another div method html? both divs enclose information varies tallness width.

<div id="wrapper">
    <div id="firstdiv">
        calm next situation
    </div>
    <div id="seconddiv">
        calm above situation
    </div>
</div>
other elements

hopefully apparent preferred outcome is:

content above situation
content next situation
other elements

when magnitude bound easy position where needed, nonetheless i need ideas calm variable. effect scenario, greatfully only cruise extent 100% both.

i am personally looking css-only fortitude (and substantially have met solutions doesn't vessel out).

there elements following this. good idea mentioned given unparalleled unfolding i demonstrated—given competence best answer, nonetheless i am looking also certain elements following aren't impacted.