To do the menu item specific override - rename the file I gave you earlier to yearbymonth_body.php and create a second file in the same folder with the name yearbymonth.php with this content
<?php
defined('_JEXEC') or die('Restricted access');
$this->_header();
$this->_showNavTableBar();
echo $this->loadTemplate("body");
$this->_viewNavAdminPanel();
$this->_footer();
Then edit your menu item and go to the 'component' tab and at the bottom in the 'Override Layout' field enter the text 'yearbymonth' - then only that menu item will pick up the multi-calendar layout.
Then add this custom CSS to your JEvents custom css file (which I have done)
.jev_month_cal {
width: 32%;
margin-right: 1%;
float: left;
margin-bottom: 10px;
}
@media (max-width: 767px) {
.jev_month_cal {
width: 49%;
margin-right: 1%;
float: left;
margin-bottom: 10px;
}
}
@media (max-width: 450px) {
.jev_month_cal {
width: 100%;
margin-right: 0%;
margin-bottom: 10px;
}
}