Font Size Change in Twenty Fifteen Theme

Hello,

I am having the most difficult time changing anything in my child theme’s style.css file.

I have tried various options, but I see no results.

As of now, I have the following code in an attempt to fiddle with font size change in title & content:

/* Content & Title Font Size Change */
.entry-title {
font-size: 7.9rem;
}

.entry-content {
font-size: 1.9rem;
}

I intentionally put the font-size to 7.9rem to see if I could see any change, but alas, nothing!

What am I doing wrong?

Any help would be appreciated.

Thank you,
madisunanne