suppose that you have some logic/programming background.
resources:
http://php.net/manual/en/function.date.php
'N' ISO-8601 numeric representation of the day of the week (added in PHP 5.1.0) 1 (for Monday) through 7 (for Sunday)
http://www.w3schools.com/PHP/php_switch.asp
<?php switch(date('N')) {
case 1: ?>
<div class="monday"> mo<!--whatever--> </div>
<?php break;
case 2: ?>
<div class="tueday"> tu<!--whatever--> </div>
<?php break;
case 3: ?>
<div class="wednesday"> we<!--whatever--> </div>
<?php break;
case 4: ?>
<div class="thursday"> th<!--whatever--> </div>
<?php break;
case 5: ?>
<div class="friday"> fr<!--whatever--> </div>
<?php break;
case 6: ?>
<div class="saturday"> sa<!--whatever--> </div>
<?php break;
case 7: ?>
<div class="sunday"> su<!--whatever--> </div>
<?php break;
default:
} ?>
you can do the same with 'if/elseif':
<?php $today = date('N');
if( $today == 1) { ?>
<div class="monday"> mo<!--whatever--> </div>
<?php } elseif( $today == 2 ) { ?>
<div class="tueday"> tu<!--whatever--> </div>
<?php } elseif( $today == 3 ) { ?>
<div class="wednesday"> we<!--whatever--> </div>
<?php } elseif( $today == 4 ) { ?>
<div class="thursday"> th<!--whatever--> </div>
<?php } elseif( $today == 5 ) { ?>
<div class="friday"> fr<!--whatever--> </div>
<?php } elseif( $today == 6 ) { ?>
<div class="saturday"> sa<!--whatever--> </div>
<?php } elseif( $today == 7 ) { ?>
<div class="sunday"> su<!--whatever--> </div>
<?php <?php } ?>
hope, i got all the brackets right ;-)