Hi,
I assume you're using the Web HTTP protocol. In this protocol the snapshots saved during recording and replay are not the images of the application's screens, but rather their HTML sources, which are then rendered in different areas of the application (snapshots, run-time viewer, report). The renderings could look different depending on the context, and we do not guarantee that they will look exactly the same as each other and as the standard browser rendering. In other words, the rendering of the application UI is just for reference, it's not meant to be the exact depiction.
If you want to see your screens in LoadRunner exactly as they appear in the browser, you're welcome to use one of the TruClient protocols.