Horizontal S_Menu

Next up: the horizontal scroll-able menu. The name tells us
what it is, a long menu on the horizontal. What to notice:

the display setting is inline-block. Below, the inline, followed by the block.
Clearly both at once is the way to go.

There is block spacing, but the content stays inline...

The other features that make this layout possible: overflow:auto (for the scroll-bar);
and white-space: nowrap (menu item will never form a paragraph).

From: W3 Schools How-to.

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The other scroll menu is the vertical one; no surprises here. Overflow becomes overflow-y;
and display is set to 'block'.

 the home button is here coded to class active( and given the green background). The
dance needs to be more complex once the user clicks on other items. 'Active' , 'link' and 'visited'
are html attributes called selectors, that allow one to style for these, with CSS.