[Theme: Ample] How to make featured posts 100% width

I’m using the business template and I’m attempting to make the featured posts take 100% width. I’ve already made a child theme with the following inside:

.single-post-image-wrap img {
    width: auto !important;
    max-width: 600px !important;
}

.tg-one-half {
    width: 100%;
}

For some reason, the lines that have !important won’t overwrite the inline CSS for the images. The classes for the images are attachment-ample-featured-blog-small wp-post-image