header slider title text is no longer centered

Hello,

I use the Sydney theme that by default has centered header slider title text as is shown in the demo at https://demo.athemes.com/sydney/. Today I updated WordPress to version 4.5.1 and I updated all the plug-ins and now the header slider title text displays in the top left hand corner of the screen. Could someone tell me how to re-establish the centered header slider title text or give me a workaround. The site I’m maintaining is https://www.what-if.ch but I have had to disable the header slider titles as it made the site partially incomprehensible.