As we have suspected recently about these changes, when changes were being rolled out across different google servers, below is a screenshot of those changes as shown in the image below, you can also read the tweet here
Coming to gmail now, Gmail team has just rolled out two new themes Preview (Dense) and Preview in gmail under gmail settings >> themes section which will make your gmail interface look like google.
Both of these themes features some what bigger font all over to make emails subjects and each email is better spaced from each other as shown in the image below.
Below is how they look in conversation view when you open an email
Do try these themes in gmail, and lets us know how do you like them, in case you don’t like these new look of gmail with these themes you can always revert back to the gmail classic theme by selecting it under gmail themes section or to revert the favorite theme of yours.