No border radius for blog entry image

Dear supporter,

How can I undo the border radius for blog entry images? I would like to have all my images without border radius on my website. Some CSS adjustments have helped me to change some of the border radius into ‘0’, but the blog entry images keeps popping-up with rounded corners.

My CSS adjustments:

.sub_menu a {
border-radius: 0px!important;
}

.rounded, .sidebar, #top .slideshow {
border-radius: 0 !important;
}

.rounded_corner{
background: none !important;
}