CSS transitions, using border-radius and RGBa colors.

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!

Big daddy link!

Growth spurt link!

Shy baby link!