Line-returns seem to be ignored

[patternhelloworld]

When a text which line-returns(\n) are inserted in, is inserted into the react-confirm-alert message property, they all get removed. In the Custom UI mode, I managed to solve the issue by replacing '\n' to a br tag, but not the Custom UI mode, I couldn't. I would like to both use your default css and apply line-returns. In the Custom UI mode, no css applied. It is like full of white stuff.