[ended] A gray train [+solution]

There is a train with 13 wagons, ending on April 26, hidden here.
You can try to find it :)

A hint was added to ITH page

Solution:
Take the RGB description of used colors:

in HEX form:
#737373 #757575 #636363 #636363 #656565 #737373 #737373

or in RGB-values form:
rgb(115, 115, 115), rgb(117, 117, 117), rgb(99, 99, 99), rgb(99, 99, 99), rgb(101, 101, 101), rgb(115, 115, 115), rgb(115, 115, 115)

It will give you either HEX codes (73 75 63 63 65 73 73) or decimal ASCII codes (115 117 99 99 101 115 115).
After decoding you will get the word success.