I am working with SXA 1.8 on Sitecore 9.0 update 2. Since Bootstrap 4 is being selected for the current site,
~/Views/SxaLayout/Bootstrap4Body.cshtml view is being used. This view has such a code:
<main> <div id="content" class="@Html.Sxa().GridPlaceholderClasses("main")"> @Html.Sitecore().Placeholder("main") </div> </main>
(I definitely know that particular view is being used since it hits in debugger), but having no components assigned into itself, it rendered with:
<main> <div id="content" class="container"> <div class="row"></div> </div> </main>
Thus there is a question: where does
<div class="row"></div> come from and should not be it empty?