I write with a blue biro pen in my daily life so I do similarly here and it makes it easier for me to see where my posts are and if someone has quoted me so I need to reply. I agree the greens, reds etc are difficult to read but the this blue is fine isn't it? Also the Disability Centre here where I work suggest that writing in black makes it harder for many people with dyslexia to read (the large amount of contrast appears to be the problem) and suggest softer colours like blue on white or cream on black are 'best practice'.