Zurb Foundation 4 default body font-size changing causes layout width issue

[Abkek]

My requirement is, if a developer type some text anywhere on the web page without a specific tag (\[code\]<p>\[/code\], etc) the font size should be same as \[code\]<p>\[/code\] tag's font-size.In \[code\]foundation.css\[/code\] I've changed the \[code\]html,body { font-size:0.85 }\[/code\]. With this edit, the whole layout (whole site template) is getting shrink. Increasing the size is causing vice-verse.Is there any other way to introduce our own default body font-size to foundation safely without harming the template? Is there any suggestions to achieve my requirement without introducing a new font-size attribute to the content wrapping div?