/fyi @mdo There might be prettier/better ways of explaining these,
        but for the sake of having accurate docs for tomorrow,
        this should do in a pinch.

[skip sauce]

* `.font-normal` is too generic. Rename it to `.font-weight-normal` for clarity.
* Rename `.font-bold` to `.font-weight-bold` so as to parallel `.font-weight-normal`.
* In docs, gloss "weight" term in relation to fonts for the benefit of non-typographiles.

Refs #18433

[skip sauce]

Closes #18141

These can be replaced by their `.text-xs-*` parallels.
This also avoids any complications from interactions between the responsive and non-responsive classes.
(e.g. `<div class="text-left text-md-right">`)

Refs #18300
[skip sauce]

[skip sauce]

Since `aria-label` is used, it's not necessary anymore.

[ci skip]

[ci skip]

Fixes grammatical erratum from cf7819d8

Mostly links.
Fixes #17056.

- Simpler main nav on all pages
- Back to purple masthead on homepage instead of dark graphite
- Active link styles on the main nav
- Cleaned up sidebar nav
- New docs layout name
- Homepage copy edits
- Updated bright purple docs color

- Credit: @adammacias
- Fixes #16499

- Replaces manual use of .bd-callout with {% callout [type] %}
- Rearranged some callouts for proximity to others
- Turned long lists of callouts--like those on tooltips, plugings, etc--into a list because holy shit that's overwhelming

.hidden is incompatible with jQuery's $(...).hide()