Remove borders Images for leaf theme?

I am trying to remove borders around the imaged for the leaf theme. I have the custom CSS plugin installed but the code that I am entering is not working. I have tried the following codes.

.entry-content img, .comment-content img, .widget img, img.header-image, .author-avatar img, img.wp-post-image {
border-radius: 0;
box-shadow: 0;
}

and

.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;
}

Please help.

Thanks in advance!