You may run into the image below with your web browser in BioStar 2.5.
The UI error happens with Chrome version 61, especially with users with Intel graphics cards because of Chrome's hardware acceleration feature.
In this case you can resolve this issue by turning hardware acceleration off.
1. Go to Settings of the Chrome browser.
2. Search acceleration.
3. Turn off Use hardware acceleration when available.
4. Close the Chrome browser.
5. Open the browser again and log in to BioStar 2.