Help to left-align search box

Hi I’m new to css so I thought this was a good place to start. I am helping to build a website for a friend and wanted to change some CSS to move the search box to left aligned instead of centre on this page https:// twistedhost(dot)net(dot)au / home-2/
I thought I had it right but I must be missing something, just note sure what?

.whmpress_domain_search_ajax form {
  display: flex;
  font-size: 16px;
  max-width: 980px;
  margin-left: auto;
  margin-right: auto;
}

Remove auto margin and the form will align on the left inside its container.