Hello Kenneth and many thanks for reply,
yes, i tried changing font in Graphene options, but without success.
I also tried disabling plugins, but again is not option.
But your remark with font problem at post-titles navigate me as last chance to style.css file, and i was looking for post-title font.
And I found “Pontano Sans” font.
When i replaced this font for Arial for example, titles are now ok!
Maybe my problem was with this Pontano Sans font, which maybe dont support czech diacritic?
Now with your help is titles right, so thank you Kenneth!