Configure default font settings as Public Sans (#264)

* Configure default font settings as Public Sans

**Why**: To reconcile differences between the brochure site and design system, update design system to reflect current typographic preferences.

Consuming projects can still upgrade and choose to temporarily bypass this change by reconfiguring it to the old setting on a per-project basis.

* Remove lingering reference to removed print guidance

CHANGELOG.md

@@ -2,8 +2,10 @@
 
 ### New Features
 - Field validation success is added to form validation ([#265](https://github.com/18F/identity-style-guide/pull/265))
+
 ### Improvements
 
+- The default font is now Public Sans for both headings and body copy. This is not being considered a breaking change, as it is the new default guidance. To preserve existing font settings to allow more time to migrate, set `$theme-font-type-sans: 'source-sans-pro';` and `$theme-font-type-serif: 'merriweather';`. ([#264](https://github.com/18F/identity-style-guide/pull/264))
 - Add Login.gov-specific component configuration. ([#258])(https://github.com/18F/identity-style-guide/pull/258))
   - [Identifier component](https://designsystem.digital.gov/components/identifier/)
   - Link colors on dark backgrounds

docs/_utilities/typography.md

@@ -8,7 +8,7 @@ redirect_from:
 
 ## Display, headings, and lead
 
-Use <code class="text-no-wrap">div.usa-prose</code> to indicate that the immediately containing headings and paragraphs should be considered a longform text document. Or jump to the [Print Guidance](#print-guidance) to learn a bit more about each style.
+Use <code class="text-no-wrap">div.usa-prose</code> to indicate that the immediately containing headings and paragraphs should be considered a longform text document.
 
 <div class="border-base-light border-left-1 padding-3 usa-prose">
   <div class="usa-display">How Login.gov keeps personal information private <span class="text-no-wrap text-secondary">(div.usa-display)</span></div>
@@ -47,14 +47,3 @@ Use <code class="text-no-wrap">div.usa-prose</code> to indicate that the immedia
     <li>Dedicated teams of design and security experts will continuously improve it.</li>
   </ul>
 </div>
-
-# Print Guidance
-
-# Merriweather Web 39px - line height 54px <span class="text-no-wrap text-secondary">(h1)</span>
-## Merriweather Web 21px - line height 30px <span class="text-no-wrap text-secondary">(h2)</span>
-### Merriweather Web 16.5px - line height 23px <span class="text-no-wrap text-secondary">(h3)</span>
-#### Merriweather Web 14.6px - line height 20px<span class="text-no-wrap text-secondary">(h4)</span>
-##### Source Sans Pro Web - All Caps 12.6px - line height 17.5px<span class="text-no-wrap text-secondary">(h5)</span>
-<h6>Source Sans Pro Web - All Caps 10.6px - line height 13.5px <span class="text-no-wrap text-secondary">(h6)</span></h6>
-
-Source Sans Prob Web 16px - line height 24.3px<span class="text-no-wrap text-secondary">(p)</span>

src/scss/uswds-theme/_typography.scss

@@ -59,6 +59,34 @@ Relative font file path
 
 $theme-font-path: if(variable-exists(font-path), $font-path, '../fonts') !default;
 
+/*
+----------------------------------------
+Type-based font settings
+----------------------------------------
+Set the type-based tokens for your
+project from the following tokens,
+or from any new font tokens you added in
+$theme-typeface-tokens.
+----------------------------------------
+'georgia'
+'helvetica'
+'merriweather'
+'open-sans'
+'public-sans'
+'roboto-mono'
+'source-sans-pro'
+'system'
+'tahoma'
+'verdana'
+----------------------------------------
+*/
+
+// sans-serif
+$theme-font-type-sans: 'public-sans';
+
+// serif
+$theme-font-type-serif: 'public-sans';
+
 /*
 ----------------------------------------
 Type scale