Custom CSS Background

[tah]

Trying to make a section use custom CSS Animation. Any help will be appreciated!

When I highlight the section and paste the code into the CSS field the entire page takes on the animation.

Here's the code:

body {
margin: 0;
width: 100%;
height: 100vh;
font-family: "Exo", sans-serif;
color: #fff;
background: linear-gradient(-45deg, #ee7752, #e73c7e, #23a6d5, #23d5ab);
background-size: 400% 400%;
animation: gradientBG 15s ease infinite;
}

@keyframes gradientBG {
0% {
background-position: 0% 50%;
}
50% {
background-position: 100% 50%;
}
100% {
background-position: 0% 50%;
}
}

.container {
width: 100%;
position: absolute;
top: 35%;
text-align: center;
}

h1 {
font-weight: 300;
}

h3 {
color: #eee;
font-weight: 100;
}

h5 {
color:#eee;
font-weight:300;
}

a,
a:hover {
text-decoration: none;
color: #ddd;
}