6 Digit Nixie Clock review

[squeezyballs]

Hi!

This is my first ever post on the EEVblog forum.

I've been working on a 6 digit Nixie Clock PCB and I would like to see your thoughts about it.
This is not my first time designing a PCB, but it is my first time with such a high voltage.
I think the clearance between the high voltage traces is good enough, but I am not sure.
The headers at the bottom of my board are for my Arduino Mega that I want to use to display the time.
If there is a cheaper alternatieve option for the Arduino Mega, please let me know.

Please comment if you see any mistakes that I have overlooked.
(This is a Eagle brd file)
EasyEDA link: https://oshwlab.com/Eggses/Nixie-clock
Components:
WS2812b
Ni-12a
1206 smd resistor
0805 smd capacitor
k155id1

Thanks in regards!