Changing font size for full width pages

Changing font size for full width pages, how can i do this?

 

Hello,
Paste the following code in your Custom CSS
(Appearance -> Theme Options -> Styling Options -> Custom CSS)

Code:

.fullwidth h1 {
font-size: 18px;
}
.fullwidth p {
font-size: 15PX;
}

you can adjust the value of font-size as per your requirement.
This will solve your issue.