Towards the end of last year we launched some pretty big design improvements for Search on mobile and tablet devices (mobile first! :-). Today we've carried over several of those changes to the desktop experience.
We've increased the size of result titles, removed the underlines, and evened out all the line heights. This improves readability and creates an overall cleaner look. We've also brought over our new ad labels from mobile, making the multi-device experience more consistent.
Improving consistency in design across platforms makes it easier for people to use Google Search across devices and it makes it easier for us to develop and ship improvements across the board.