When I want to force reload CSS and JS on my sites (non-Magento 2), I usually just add a query string to the end of the URLs. For example:
I tried this in M2 by adding adding the above to my style files in my custom
default_head_blocks.xml Although the style files are being loaded (I can click on the links in 'View Source' and it shows me the correct CSS file content) but the page isn't being styled.
Any idea why it's not working? Or, do you know how to force reload CSS / JS on the client side in M2?