DNN CMS has included an overlay transparency when you are in edit mode. This sometimes quite annoying especially when you have a white background and this layer has caused a blur effect overlaying the content of your site. Although it is only appears in edit mode, many site owners find it a bit frustating.
To disable this is pretty easy, you can include the following css style on your skin.css file or you can place this style directly under Site Settings > StyleSheet Editor.
.dnnEditState .DnnModule { opacity: 1.0; }