Let's say this is my website:

```css
* {
  font-family: Papyrus, nothing;
  font-size: 30px;
  line-height: 100%;
}
```

```html
Qui legit haec est mirabilis ❤
```

Now, the `❤` is not written in Papyrus, because it's no glyph of this font. I would like to generally hide all glyphs that do not exist in the font file. Taking the `notdef` glyph of the font file instead would be also fine. I want to use it for an editable text area later. So doing it manually doesn't help me.

How is it possible to do that?