Font changed on my browser / Yahoo

Hi, I am new on this forum and would like to have some help.
I added some fonts to my windows 8 computer.
Now when I start my email Yahoo, the layout has changed to a ugly bolt font
Can I reset this to the original setting ?
I have check with my laptop and there everyhting is normal on the layout

I just checked with a other browser this is ok, so the problem seems to be with Google Chrome ?

Thanks to help
Osty