[web] Fix undesired scrollbars on shell files

[jspast]

While testing my game, I noticed scrollbars were visible when compiling with minshell.html. First, I thought my RenderTexture was not scaling correctly on the web. After some tests, I discovered that a small change to the minshell.html file completely fixes the problem.

The issue has already been described here.

And even the solution has already been described here but not merged.

I also added background-color: black to the body so that areas not rendered (happens when resizing the window or when not scaling the game) are black instead of white, which I assume should be the default.

Then I checked shell.html and found that it always shows a horizontal scrollbar, even with no RenderTexture scaling. This can also be fixed directly on the shell.html file.

So hopefully these changes make the shell files behave as expected.

Tests

(For minshell.html I used a modified version of core_basic_window that scales using a RenderTexture)

minshell.html before:

minshell.html after:

shell.html before:

shell.html after:

[raysan5]

@jspast thanks for the review! I just fixed it for one of my projects today! Still wondering the root of this issue, why does it happen?

[jspast]

Thanks @raysan5 for the merge! To be completely honest, I am also not sure! I was just able to find a solution and thought it was a good idea to help people like me who have no experience with web development.