Document resize in README and tune H5Web cell height

[loichuder]

Fix #91

Should we do something else ? Bump the default height ?

[axelboc]

Here is an idea:

aspect-ratio: 16 / 10;
min-height: 500px;
max-height: 75vh;

We get everything:

• optimal height of 75vh (see below) with optimal aspect-ratio of H5Web on 16/10 viewports ;
• cap of 75vh on wider ratios so the viewer remains entirely visible ;
• min height of 500px :
  • so the viewer doesn't shrink too much on wide but very short viewports ;
  • so the viewer doesn't shrink too much on narrow viewports (think portrait orientation or half-screen window) ;
  • to act as fallback on browsers that don't support aspect-ratio.

I'm suggesting 75vh instead of 80vh, to allow for the code cell above the viewer to remain somewhat visible. I feel that it's important to keep the path of the file that is being viewed on the screen. Also, I think it's important to keep enough space above/below the viewer for people who configure their mouse wheel to jump more lines than usual on scroll. You don't want them to have to scroll back and forth or drag the scrollbar to move the viewer in the middle of the viewport...