That's up to @shetch it's his code.
The issue is with bootstrap scss
line 114
$contents[] = array('text' => tep_draw_separator('pixel_black.gif', '100%', '1'));
The height of "1" is beeing over ruled by the scss
.img-fluid {
max-width: 100%;
height: auto;
}
So simple hack fix set /public_html/admin8262/whos_online.php
<style>
.img-fluid {
max-width: 100%;
height: 1px!important;
}
</style>
@shetch I'm sure will have a proper fix in time. For now works ok.