You can achieve this with CSS by using the user-select property. You can try it below:
rt { -webkit-touch-callout: none; /* iOS Safari */ -webkit-user-select: none; /* Safari */ -khtml-user-select: none; /* Konqueror HTML */ -moz-user-select: none; /* Old versions of Firefox */ -ms-user-select: none; /* Internet Explorer/Edge */ user-select: none; /* Non-prefixed version, currently supported by Chrome, Edge, Opera and Firefox */}<ruby><rb>漢</rb><rt>かん</rt></ruby><ruby><rb>字</rb><rt>じ</rt></ruby>You can check the Can I Use information for browser compatibility.