A Closer Look at CSS 7. font size step four =not working dont understand

body {
height: 100%;
margin: 0;
text-align: center;
width: 100%;
}

h1 {
font-size: 32px;
font-family: Palatino, ‘Palatino Linotype’, serif;
color: rgb(121,149,117);
}

h2 {
font-size: 56px;
}

.hero {
font-family: ‘Trebuchet MS’, Helvetica, sans-serif;
}
.hero {
padding: 250px 0;
margin: 30px;
font-family: ‘Trebuchet MS’, Helvetica, sans-serif;
}

p {
font-size: 2rem;
}

.hero a {
color: #00FFAA;
font-size: 24px;
text-decoration: none;
}
It says I’m supposed to:
Now let’s resize anchor elements that are children of elements with the “hero” class using em values.

In main.css locate the .hero a selector. Change the font-size property to 1.25em;.

Click Run to see the anchor element’s size decrease.

HELP!!! How do I do this?

Can anyone help me? I really don’t know what to do here!!

Please post a link to the exercise. Thanks.