Homepage not loading correctly, but then loads when refreshing

Hi. When going to our homepage (www.whiteskitchen.co.uk). We seem to have lost the styling on the homepage. I checked the source code and it’s not fully loading the page.

When you refresh the page or click on a link, the page reverts to the correct theme styling and loads correctly. The stylings are very different and you’ll notice the difference

Any ideas what it could be? It only started happening a couple of days ago and no updates or changes have been made before or after the issue cropped up

The site I need help with is https://www.whiteskitchen.co.uk.