I installed the Example Skin at php7.1 and mw 1.31.5 (with and without installed oyejorge/less.php 1.7.0.14), but there is no sufficient less-function ( i changed colors without effect for test) -
*** and the navigation is at the bottom....(with the github master i get an error about sanitizer...)
P.S. I found it partially myself , but...: In variables.less (at the top) should stand
@import "$IP/resources/src/mediawiki.less/mediawiki.mixins";
But after login as a user the styling disappeares again...
If You publish a template then it should function !