This seems to be some kind of cache issue. Follow these steps (assuming Google Chrome):
1. Press CTRL + SHIFT + I while browsing the web page (this should open the inspector)
2. Press CTRL + SHIFT + R (this should refresh the page and clear the cache)
If it is working now, then it is confirmed it is a (local) cache issue. If it is not, it could still be the server caching the CSS file
3. The programmatic way to avoid the CSS from being cached in the server is changing the CSS URL. That should fool the server cache and force a new download of the CSS file. This approach would also fix the issue for all users (not just the ones that followed steps 1 and 2). In order to change the URL you should:
a. Edit file qa-theme/SnowFlat/qa-theme.php
b. Add or merge this function:
public function css_name() {
return 'qa-styles.css?' . QA_VERSION . '_1';
}
c. Keep the _1 for the first time. Each time you make a change to the CSS make sure to increase the number. It should look like _2 next time.