When I put some text with special characters into password area (for example: "Příšerně žluťoučký kůň"), some letters is rendered with the default browser font.

When you copy the encrypted text, there is an extra character at the end (maybe some end of a row or something similar).

Suggestion for fix

I suggest to display "Fork me on Github" like normal button next to "How it works" to prevent glitches and make UI more unified.

Twitter link overlaps the content in case of long text or small viewport height.

Suggestion for fix

I suggest to display Twitter button like normal button next to "How it works" to prevent glitches and make UI more unified.

Pitty you can't use passion to share password securely over any messenger that previews links.

When using Whatsapp you (should) get end-to-end encryption, so in transit it should be fine. And realistic attack vector is someone finding the link later after decrypting the communication. So having "disposable" link is a good way to secure it. But as whatsapp previews the link it withdraws the password.

If there was a rather simple password that could be shared along with the link, the password would not be withdrawn by simple preview. Or even a button press to withdraw the password would do. The password would still be safe because as soon as it's withdrawn by the other side it's gone - and that's realistically well before anyone can decrypt the conversation.