Images missing max-width property

[paskal]

Hello!

Thanks for a very nice theme! I've stumbled upon the very same issue as the dim0627/hugo_theme_beg#19, only part of the image visible on the screenshot where whole should be. Source code:

![Shinken simple distributed architecture](https://shinken.readthedocs.io/en/latest/_images/shinken-architecture.png)

Only several sub-themes affected:

jeen:

freelancer:

aloud:

[fiatjaf]

I'm slowly improving themes. I haven't touched the ones you mentioned for a long time now, that's why they have a lot of weak points. I've quickly fixed the max-width for images in them on fiatjaf/classless@12e4515, but they still need more love.