Firefox fail to bold content

[brynne8]

Description

Try to use Firefox 58 to use medium editor. In the sample, the bold button fail to function. Same operation is OK for Chrome. Besides, the italic and underline buttons are both OK.

Steps to reproduce

1. Open https://yabwe.github.io/medium-editor/
2. Select text and click Bold button

Expected behavior: bold text

Actual behavior: fail to be bold

Versions

• medium-editor: 5.23.2
• browser: Firefox 58.0
• OS: Windows 7 x64

[linkesch]

This is not an issue on the actual full demo page here: https://yabwe.github.io/medium-editor/demo.html. It's an issue only on the simple demo page where

font-weight is already set to 500 which Firefox interprets as bold so hitting bold button does nothing.

So this is not a bug in medium-editor, but our homepage instead.