Emacs blue (on dark background) is too dark.
classA is readable with difficulty in the example below:
How to fix the dark blue colour?
Put the cursor on the blue word, and say
C-u C-x =. Find the
face entry and click on its value. Then click on
customize this face and change the foreground value to e.g.
If you are in a console or are doing
emacs -nw in a terminal, instead of clicking, put the cursor on the appropriate element and press
Faces in Emacs can have different values, depending on display attributes such as the number of colors supported or whether they're displayed on a light/dark background. Emacs can guess the latter without any issues in graphical mode, for textual frames however the guessing isn't nearly as good. If it turns out to be wrong, you'll get dark blue on black (because it mistakenly assums a light background on which there would be enough contrast to the dark blue), like in the screenshot above.
To check whether that's the case for you, inspect the value of
frame-background-mode and customize it if needed.
(setq frame-background-mode 'dark)