Recently some UI improvements around the Manage Jenkins page have been introduced. The visual changes are very subtle but behind them, there are interesting benefits.
Some of the goals that we have tried to achieve:
Applying a semantic HTML
Removing the <table> tag usage for implementing layouts and content structures. Read this article if you want to know reasons and/or arguments.
Small re-styling focused on spacing, margins, composition,...
Philadelphia Jenkins Area Meetup
Jenkins Pipeline Development with JobDSL, PipelineUnit and Jenkins Test Harness