Minor: Made every .container into a <section>

• Turned every `div.container` element into a `section.container`.	» So that we can use <header> tags where we want and still be HTML-semantically correct.
Fix: `.vert-*-block .inner` & `.monologue` w/o `p`

• Changed `.vert-block()` to affect only `.inner` children, and made those children in `index.html` `div.inner`s.
	» I keep messing up the layout by putting multiple elements insider of a `vert-middle-block` when there should only be one.
• Eliminated the `p.monologue` tags in `index.html`— they're now `div.inner`s.
	• Added `.monologue` to each phase's <section>— since the whole thing's a monologue anyway.
		» Seems to work as expected.
All font-sizes, headers, emboldening

• All font-sizes now match the mockup:
	◦ Initial `container`'s `verse`s are now wrapped in an <h1>
	◦ Other containers use <header> for stand-out large text (instead of <span>)
	◦ <em> used throughout to step up the font a bit
• New CSS rules under .monologue:
	◦ `em` at `@em-strong-font-size` (2× the base, 48px)
	◦ `em` & `b` combinations at `@em-strong-font-size` with cabin-sketch-bold
	◦ `.header()` mixin makes sure <small> elements within use the inherited color (instead of Bootstrap's re-color), and are sized at `@small-header-font-size` (2× the base, 48px)
	◦ `h1` rule uses `.header()` and adds a much larger font-size for itself (3× the base, 72px)
	◦ `header`/`h2` rule uses `.header()` and adds a larger font-size for itself (2.5× the base, 60px)
Italicization

• Change a whole bunch of `span.verse`s to `i.verse`s.
	• Wrapped the contents of the 1st-container-<h1>'s 2nd line with <i> instead, since it's already a <small>.
• New monologue `.i` CSS rule to force `oblique` styling.
	» Selector is `i, i *` because it doesn't inherit into the `b` tag properly otherwise!  F'ing browsers…
Left/right padding

• New `.text-pad-left-*`/`.text-pad-right-*` classes provide `padding-left`/`-right` presets in `em` increments of `0.25`, `0.333`, `0.5`, `0.666`, `0.75`, `1`, `1.25`, `1.333`, `1.5`, `1.666`, `1.75`, `2`, and `2.5`.
	• Placed `.text-pad-right-*`s on left-half/text-right cols and `.text-pad-left-*`s on right-half/text-left cols to match the mockup.