How could I do this is JSON?

I want to use JSON so I can make a fake 56K modem wipe effect, This is just a rushed example of the simple version using style and frames. Any help is appreciated as I have had fun making my own tools.

div {
width: 100%;
height: 720px;
background: red;
position: relative;
-webkit-animation-name: modem wipe;
-webkit-animation-duration: 14s;
-webkit-animation-fill-mode: forwards;
animation-name: example;
animation-duration: 14s;
animation-fill-mode: forwards;

@-webkit-keyframes example {
from {top: 0px;}
to {top: 720px; background-color: red;}