Highlighting external links
Follow CSS code add small SVG allow on the top of the extrenall links:
a[href*="//"]:not([href*="ozzyczech.cz"]):after {
content: url('data:image/svg+xml;utf8,<svg version="1.1" xmlns="http://www.w3.org/2000/svg" x="0px" y="0px" width="14px" height="14px" viewBox="0 2 12 14"><g style="opacity:0.75;" fill="currentColor"><polygon style="fill-rule:evenodd;clip-rule:evenodd;" points="2,2 5,2 5,3 3,3 3,9 9,9 9,7 10,7 10,10 2,10 "/><polygon style="fill-rule:evenodd;clip-rule:evenodd;" points="6.211,2 10,2 10,5.789 8.579,4.368 6.447,6.5 5.5,5.553 7.632,3.421"/></g></svg>');
}PS: do not forgot change href*="ozzyczech.cz" in CSS code 😀