Increase size of feature image in Wave theme

Currently, the official Wave theme displays small (1:1) feature images on the home page and at the top of posts. Is there an easy way to increase the size to accommodate larger (e.g., 16:9) images? Ideally, it would be nice to have the image above the title on the home page (similar to Casper).

You can add this in the Code injection area to change the style:

.post-feed .post, .player { flex-direction: column; }
.post-media {  
    width: auto!important;
    margin-bottom: 25px;
    margin-right: 0!important;
.post-media .u-placeholder:before {
    padding-bottom: 56.25%;