feat(navbar): match head shows the other gym's brand, centred logo on CrossFit, mobile band

The match head is painted in the other gym's colours with a strip in this site's accent; below 992px it is a slashed band at the bottom of the open menu (menu height from the real header height). The CrossFit page gets the centred logo crossfade, the hero logo has a fixed 52px height, and the hero h1 shadow is softer with the frosted blur at .8.

site/crossfit.php

@@ -1,6 +1,7 @@
 <?php
 // Was Home::crossfit.
 $current_uri_2 = 'crossfit';
+$nav_center_logo = true;   // big centred logo over the video, docks left on scroll (navbar.php)
 
 // Old /home/crossfit links → the default gym's CrossFit page.
 if (($_GET['gym'] ?? '') === '') {