I have exhausted all possible permutations I could possibly try, like moving all of the .js code into the html, but the functions would not run from the doc' sidebar, in every run -click any of those buttons- I have to go back to the script's editor to run the sidebar. The script for functions I embedded in my html is:
function Check() {
google.script.run.results_run();
}
function Clear() {
google.script.run.results_clear();
}
<button type="button" class="c-btn c-btn--primary" onclick="javascript:Check();"> Check </button>
<a class="clear-highlights" onclick="javascript:Clear();">Clear highlights</a>