This library is great, tested and will be used for my girlfriend's project.
But, has anyone brought out the point that using regular 74HC595 shift register is actually a bad design as you are forcing it to drive harder then it's rated for?
Yes, each IO is rated for 20mA, but supply/GND current is only rated to 70 mA. All outputs 'on' would be 160 mA with 20mA LEDs. 160 > 70
I suggest a TLC5916 instead as it's rated to drive LEDS like this and it has built in Constant Current driver, so you don't need to add resistors in series with each LED.