Trying to simulate user inputs in CefSharp3 (OffScreen) using JavaScript

I am trying to simulate the user operation on CefSharp(OffScreen) using JavaScript.

Once I load the page (https://www.w3.org),
I am trying to search in the search bar,
click the search button
open first result

So I have used,

            await browser.EvaluateScriptAsync("document.getElementsByName('q')[0].value = 'CSS';");
            await browser.EvaluateScriptAsync("document.getElementById('search-submit').click();");
            await browser.EvaluateScriptAsync("document.getElementById('r1-0').click();");

But the issue I am facing is, to take screenshot, I have to use Thread.Sleep(x) in between and at the end for the pages to load before doing the next operation or take the screenshot.

Is there anyway to avoid the SLEEP and detect when the loading is done, to do the next operation?

I tried ExecuteScriptAsync also, same issue with that also.