If you are one of those users bored with default user interface of Gmail, why go and dress up your Gmail with various themes available from themes in settings.Google added 5 more themes to Gmail includes Android, Basic Black, Black White,Tree Top and Marker.
Gmail Interface fills totally block color when you choose Basic Black,Gmail layout looks white when you chosen Basic White. Basic White is OK, Basic Black looks not good .
If you are Android lover you can turn Gmail interface with Android theme, looks cool. Tree Tops theme for Gmail is OK, but Marker theme looks good.
These five themes are now available for Gmail, sign into your Gmail account>setting>Themes choose you desired and favorite theme from the five.