Please fix the bugs about alpha in _applications.scss

[wangxa]

From line 1678, the alpha definitions look like alpha (#000, 0.3). But in the generate CSS files, it is alpha #000, 0.3. So if you run gtk3-widget-factory from a terminal, you will see the error message. Since the function gtkalpha has been defined in _common.scss, these error alpha codes should be replaced using gtkalpha. And by the way, it is good if removing the whitespace between the function name and '(' for CSS.

[vinceliuice]

thanks for your reminder, I'll fix this soon