impressConsole: View end Preview iframes not scaled correctly for large presentation widths

The impressConsole seems not to scale down correctly the content of the slideView and preView iframes, when the width of the slides is larger than the default 900px.

I have a presentation for a screen width of 1920x1080px, for which I have set the slide width to 1700px:

```css
.step {
position: relative;
width: 1700px;
/* ... */
}
.slide {
width: 1700px;
height: 1000px;
/* ... */
}
```

When I open the impress console, both the content of slideView end preView is not fully visible, since it's not scaled down sufficiently.

I tried to scale down the iframe with:
```css
iframe#slideView div#impress {
transform: scale(0.46);
}
```
but this does not work - maybe it's just incorrect css, or the wrong place to do it (default css file)

Any ideas how to fix this?
Thanks,
Tobias

Reproduce the issue in impressConsole with a 1700px slide width and inspect how the slideView and preView iframes calculate their scaling against the default 900px width. Compare the visible area with the 1920x1080 example; done means both iframe contents are fully visible at larger presentation widths without manual CSS overrides.

Written by the indexing model from the issue text.