CSS styles not loading

[PaddyM]

I am building a medical database for use in webdirect

For the past 3 versions of filemaker server (13,14,15),  I have encountered the same problem 

 

When loading the styles to the browser, 95% of the time the design appears as normal. However, every now again certain pages load without the style, leaving a white screen with the text only

 

My file is currently being hosted on filemaker server 15, but I think I will upgrade shortly to 16

 

I have been using a supported theme which I have adjusted to suit my needs

 

it's very frustrating because it is preventing me from presenting the software outside the office, as I don't want this to happen during a presentation

 

Has anyone experienced similar problems, and if so, have you managed to find a solution?