How can I remove the shadow from an image in a widget?

The theme I am using is Harmony 2.0 which is a child-theme of TwentyTwelve.

My website is located at https://86svjl80v3x.technomum.co.uk (a sandbox site)

I have placed the social media icons in the footer widget and have put the following code in the style.css in the child theme

.entry-content img, .comment-content img, .widget img, img.header-image, .author-avatar img, img.wp-post-image {
    border-radius: none !important;
    box-shadow: none !important};

As you can see the code hasn’t worked!!

Can anyone help me remove the shadow?

Thanks.