Question: I was refactoring some code and decided to change the usual `style="display:none"` to use the HTML5 `hidden` attribute, in order to hide a button. Only to find that it is not compatible with bootstrap's `btn` class. That said, I will keep using the style display attribute but I wonder if this is a bug that should be reported or simply a feature that everyone should be aware of.

The corresponding jsfiddle can be found [here](https://fiddle.jshell.net/56ax4phv/)

Answer: 
Try adding this to your css:

```
*[hidden] { display: none !important; }

```

for example; <https://fiddle.jshell.net/bh8h5tya/>
It's not hidden because bootstrap applies `display: inline-block` on the class `.btn`

Bootstrap provides the following `.hidden` class that you can use to show/hide elements. Try using that.

```
.hidden {
  display: none !important;
}

```