does WP now overwrites custom editor style font?

Hi all

I use a custom-editor-style.css file to edit my WP visual editor’s font family and size.
It used to work fine. But now somehow the font type is overwritten with a tahoma font, which is not in my custom style file. I think this started to happen with WP 4. Does WP now sonehow overrides visual editor’s font type?

My file does what it is supposed to do fine regarding the font size, weight and height. Only the font family now has no effect, no matter how I change it.

Here is the content of my css file:

body{
font-family: Arial, sans-serif;
font-size: 100%; /*change according to your desire*/
font-weight: 600; /*change according to your desire*/
line-height: 1.4; /*change according to your desire*/
}