Changing font size in body & Size of H2 & H3 Headers

I am using areveiew theme, where would I go to change font in the body text. At present it looks like it is showing 8 point(8px) I went into Appearance, Editor and choose Style Sheet Style. CSS and seen this code:
body {
line-height: 1.5;
word-break: break-word;
-webkit-font-smoothing: antialiased;
font-family: ‘Source Sans Pro’, sans-serif;
font-size: 14px;
color: #8F8F8F;
background: url(‘pattern.png’);
background-color: #222E38;
-webkit-backface-visibility: hidden;
}
h1,
h2,
h3,
h4,
h5,
h6 {
font-family: ‘Roboto Condensed’, sans-serif;
color: #444;
}

it says font size 14px, but as I mentiones type on site looks 8 point.

Can some direct me to proper places for changing body text size and also header sizes.
Thanks