When you narrow the browser the styles are not reloaded. Check the same on real devices and let us know if you have the problem. When you narrow the browser reload the page, do you still see the problem?
Please check the site on all the real devices and let us know if you have any problems.
When site is opened on a mobile phone the certain styles are uploaded. When the site is opened on the desktop, other styles are uploaded. When you narrow the browser the certain styles are uploaded only after you refresh the page, this is the behaviour of any browser and we cannot influence that.