Add large image to demo site

[jorisvandenbossche]

cc @hoetmaaiers I added a larger image to the demo site. But this mostly already seems to work OK (similar to bootstrap's img-fluid), since sphinx includes a max-width: 100% for img

[hoetmaaiers]

Ok, then I guess the max-width of 100% solves the scrolling question unless we intent to remove the max-width: 100% rule?

[jorisvandenbossche]

For figures at least, yes (other things like tables still have scrolling issues). You are not a fan of using max-width: 100% for figures (as the default)?

[hoetmaaiers]

I do like max-width 100%, for enlarging it, a Lightbox-like solution would have my preference (if ever needed of course).

The scrolling issue for tables should be fixed in #174