After short research I saw that Allegro ('Polish Ebay') had the same problem on Desktop Chrome months ago. After couple more hours of reading documentation I found a clue, that Webkit is freaking out if you try to put HTML content into style tag. So I switch
var cssStyle = document.createElement('style');
cssStyle.innerHTML = 'body { color: #000; }';to var cssStyle = document.createElement('style');
cssStyle.innerText = 'body { color: #000; }';and everything works.