I need to calc font-size using CSS (CurrenSize + px). 
for example:

```
body * {font-size: calc([CurrenSize] + 3px) !important;}

```

I do that in jQuery but not working smoothly, so I'm asking if I can do that in CSS. 
in CSS (this code working, but the 100% make the text very small that why i need the current font size):

```
body * {font-size: calc(100% + 3px) !important;}

```

in js

```
 $("body *").css('font-size','+=3');

```