New hideout theme - improve display for larger screen

[magdmartin]

We should also setup a layout for larger screens (mine is 1920x1080) so that the .container is allowed to flex out wider or if I shrink my browser window then it goes back to some minimum. Looks like the current width for the .container Box itself is too small by default on larger screens. Look at some of the examples and everything on this page to use Flexbox more effectively https://css-tricks.com/snippets/css/a-guide-to-flexbox/#flexbox-examples

initially reported here