Reply To: How to change font size and style sitewide

Add these code on the Custom CSS option. Or styles.css, but only if you’re using a child theme.

The first part (14px/20px) is the font-size and the line-height.
The second part is the font-family to be used. You can replace “Arial” with any available font you want.

for the post titles on excerpts:

.blog-view .entry-title a {
    font: 14px/20px arial, sans-serif;
}

for the text on excepts:

.blog-view .entry-excerpt {
    font: 14px/20px arial, sans-serif;
}

for the post titles on single posts:

.single-view .entry-title a {
    font: 14px/21px arial, sans-serif;
}

for the content on single posts:

.single-view .entry-content {
    font: 14px/21px arial, sans-serif;
}