I've just realized I was pointing it to the RTL styles. I was confusing it with my updated structure.
Add this function to your qa-theme.php file:
public function css_name()
That's most likely to be what @GateOverflow said.
You need to force browser update by adding a file version query string to your CSS link.
If you want to test if that is case, refresh your page by pressing the keys:
Ctrl+F5 - if you're on Windows
Command+Shift+R - Mac
This will force browser cache refresh just for you.
SnowFlat theme has a query string embedded with the Core because SnowFlat updates usually come in conjunction with Core updates. So SnowFlat already has a query string version attached to the CSS link. Same as the core.
To add or update a query version to your updated SnowFlat theme, go to:
Q2A > qa-theme > Snowflat > qa-theme.php - Line64
$this->content['css_src'] = $this->rooturl . 'qa-styles-rtl.css?' . QA_VERSION;
Update it to this:
$this->content['css_src'] = $this->rooturl . 'qa-styles-rtl.css?v=001';