inter/docs/index.html

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<div class="row"><div>
  <h1>The Inter UI font family</h1>
  <p>
  Inter UI is a typeface specially designed for user interfaces
  with focus on high legibility of small-to-medium sized text on computer screens.
  </p>
  <p>
  The family features a tall x-height to aid in readability of mixed-case and
  lower-case text. Several OpenType features are provided as well,
  like contextual alternates that adjusts punctuation depending on the shape of
  surrounding glyphs, slashed zero for when you need to disambiguate "0" from "o",
  tabular numbers, etc.
  </p>
</div></div>

<div class="row white" style="padding-bottom:0"><div>
  <p id="samples" class="samples items sample-images">
    <a href="samples/" class="plain"><img src="samples/img/01.png" srcset="samples/img/01@2x.png 2x" width="888"></a>
  </p>
  <p style="text-align:center">
    <a href="samples/" class="plain">More samples -></a>
    <br><br>
  </p>
</div></div>

<div class="row dark"><div>

  <h2><a id="usage" href="#usage">How do I use it?</a></h2>
  <p>
    Using the font is as easy as
    <a class="download-link" href="https://github.com/rsms/inter/releases/latest/">download &amp; installing</a> locally on your computer.
  </p>
  <p>
    You're free to bundle copies of Inter UI with your software, even if it's
    commercial and you charge money for your software. Inter UI can also be used
    on the web by either hosting the font files yourself or by including this CSS:
  </p>
  <code>@import url('https://rsms.me/inter/inter-ui.css');</code>
  <p>Use the following CSS rules to specify the Inter UI family:</p>
  <code>font-family: 'Inter UI', sans-serif;</code>

  <p>&nbsp;</p>

  <h2 id="dynamic-metrics"><a href="{{url_root}}dynmetrics/">Dynamic Metrics</a></h2>
  <p class="dynmet-calc">
    Size
    <input id="dynmet-font-size" type="number" value="12"
    ><span title='Display points — "px" in CSS, "pt" on iOS, "sp" on Android, and "pt" (1/72 of an inch) in print'>dp</span>
    <span class="arrow">=</span>
    <span title='letter-spacing in CSS; also called "tracking" in some software.'>spacing
    <input id="dynmet-tracking" type="number" value="0.008">
    <span id="dynmet-unit">em</span>
  </p>
  <p>
    There's of course no absolute right or wrong when it comes to expressing yourself with typography, but Inter UI <em>Dynamic Metrics</em> provides guidelines for good typography. You simply provide the optical font size, and the tracking and leading is calculated for you to produce the best results.<br>
    <a href="{{url_root}}dynmetrics/">Learn about Dynamic Metrics —></a>
  </p>

  <p>&nbsp;</p>

  <h2><a id="free" href="#free">How much does it cost?</a></h2>
  <p>
    Inter UI is a <a href="https://github.com/rsms/inter">free and open source</a> font family. You are free to use this font in almost any way imaginable.
    Refer to the <a href="https://choosealicense.com/licenses/ofl-1.1/">SIL Open Font License 1.1</a> for exact details on what the conditions and restrictions are.
  </p>

</div></div>

<div class="row"><div>
  <h2><a id="weights" href="#weights">Weights & Styles</a></h2>
  <p>
  There are six weights, each with italic counterparts,
  making a total of 12 styles.
  </p>
  <img src="res/weights-and-styles.svg" style="opacity:0.88;width:100%;display:block;margin:3em 0 3em 0">
</div></div>



<div class="row white variable"><div>
  <h2><a id="variable" href="#variable">Variable</a></h2>

  <p>
  Inter UI is offered as both traditional constant font files
  (one per style, e.g. Bold Italic, Medium, etc.) as well as a
  <a href="https://en.wikipedia.org/wiki/Variable_fonts">Variable Font</a>
  file which contains all styles in a much smaller file size.
  Additionally, a variable font is ...variable! You can mix and match weight
  and italic angle as you please, forming theoretically infinite variations.
  </p>

  <div class="unsupported-message">
    <p>Variable Fonts not supported by this web browser</p>
  </div>

  <div class="ctrl">
    <div class="ctrlrow">
      <label title="Weight in the range of 400 to 900">
        <span class="label var">Weight:</span>
        <input type="range" value="400" min="400" max="900" name="weight">
      </label>
      <label title="Slant angle in the range of 0° to 10°">
        <span class="label var">Slant:</span>
        <input type="range" value="0" min="0" max="10" step="0.01" name="slant">
      </label>
      <label class="tight">
        <input type="checkbox" name="animate"> Animate weight &amp; slant
      </label>
      <label class="tight">
        <input type="checkbox" name="invert"> Negative
      </label>
    </div>
    <div class="ctrlrow">
      <label title="Font size">
        <span class="label">Size:</span>
        <input type="range" value="96" min="11" max="400" name="size">
      </label>
      <label title="Space between letters">
        <span class="label">Tracking:</span>
        <input type="range" value="0" min="-0.1" max="0.1" step="0.001" name="letterSpacing">
      </label>
      <label>
        <span class="label">Line height:</span>
        <input type="range" value="1.2" min="0.7" max="2" step="0.01" name="lineHeight">
      </label>
    </div>
  </div>
</div></div>
<div class="row white variable-sample-row">
  <div class="variable-sample" contenteditable>
  ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890
  ?!()[]{}&*^%$#@~
  </div>
</div>
<script src="index-var.js?v={{ index_var_js_v }}"></script>
<div class="row white"><div>
  <p>
    Variable fonts is a new technology and support is somewhat in flux at
    the time of writing this (fall 2018.)
    <a href="var-test.html">This test</a> can be used to discover
    what a web browser is capable of.
  </p>
</div></div>



<div class="row"><div>
  <h2><a id="features" href="#features">Features</a></h2>
  <p>
    Inter UI comes with many OpenType features that can be used to
    tailor functionality and aesthetics to your specific needs.
    Some of these features can be combined to form a great number of
    alternative variations.
  </p>
  <boxes class="features">
    <box>
      <h3>Contextual alternates <q title='OpenType feature ID'>calt</q></h3>
      <p>
        This feature is enabled by default and causes certain characters to
        adjust themselves or be replaced depending on the surrounding context.
      </p>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>12<em>:</em>34,  FE<em>—</em>X</in><to></to><out>12:34,  FE—X</out></r>
        <r><in>4<em>.</em>2</in><to></to><out>4.2</out></r>
        <r><in><em>(</em>SEMI<em>)</em>PERMANENT</in><to></to><out>(SEMI)PERMANENT</out></r>
        <r><in>SFO <em>-></em> STO</in><to></to><out>SFO -> STO</out></r>
        <r><in>IIA <em>—></em> OGG</in><to></to><out>IIA —> OGG</out></r>
        <r><in>ARN <em><--></em> OGG</in><to></to><out>ARN <--> OGG</out></r>
        <r><in>M<em>@</em>N m@n</in><to></to><out>M@N m@n</out></r>
        <r><in>Smile <em>:-)</em></in><to></to><out>Smile :-)</out></r>
      </t></tablex>
      <p>
        There are many more contextual alternates.
      </p>
    </box>

    <box>
      <h3>Tabular numbers <q title='OpenType feature ID'>tnum</q></h3>
      <p>
        Fixed-width numbers are useful for tabular data, where comparing
        columns across rows is desired.
      </p>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>1234567890</in><to></to><out class="tnum">1234567890</out></r>
        <r><in>1131711<em>&nbsp;</em></in><to></to><out class="tnum">1131711<em>&nbsp;</em></out></r>
        <r><in>0040900<em>&nbsp;</em></in><to></to><out class="tnum">0040900<em>&nbsp;</em></out></r>
        <r><in>11:31,711<em>&nbsp;</em></in><to></to><out class="tnum">11:31,711<em>&nbsp;</em></out></r>
        <r><in>00:40.900<em>&nbsp;</em></in><to></to><out class="tnum">00:40.900<em>&nbsp;</em></out></r>
        <r><in>0.45, 0.91, +0.08<em>&nbsp;</em></in><to></to><out class="tnum">0.45, 0.91, +0.08<em>&nbsp;</em></out></r>
        <r><in>1.00, 9.44, −0.13<em>&nbsp;</em></in><to></to><out class="tnum">1.00, 9.44, −0.13<em>&nbsp;</em></out></r>
        <r><in>0.00, 1.13, +7.12<em>&nbsp;</em></in><to></to><out class="tnum">0.00, 1.13, +7.12<em>&nbsp;</em></out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Numerators <q title='OpenType feature ID'>numr</q></h3>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>Hello <em>0123</em></in><to></to><out class="numr">Hello 0123</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Denominators <q title='OpenType feature ID'>dnom</q></h3>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>Hello <em>0123</em></in><to></to><out class="dnom">Hello 0123</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Superscript <q title='OpenType feature ID'>sups</q></h3>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>H<em>ello 0123</em></in><to></to><out class="sups">Hello 0123</out></r>
        <r><in><em>abcdefghijklm</em></in><to></to><out class="sups">abcdefghijklm</out></r>
        <r><in><em>nopqrstuvwxyz</em></in><to></to><out class="sups">nopqrstuvwxyz</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Subscript <q title='OpenType feature ID'>subs</q></h3>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>H<em>ello 0123</em></in><to></to><out class="subs">Hello 0123</out></r>
        <r><in><em>abcdefghijklm</em></in><to></to><out class="subs">abcdefghijklm</out></r>
        <r><in><em>nopqrstuvwxyz</em></in><to></to><out class="subs">nopqrstuvwxyz</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Fractions <q title='OpenType feature ID'>frac</q></h3>
      <p>
        This feature is contextually sensitive and will convert "words" of
        numbers separated by forward slash into proper fractions.
        This feature is dynamic and allows for any fractions.
        Note that the digits used for fractions are custom-made for their
        small size, and are even made separately from the slightly larger
        Superscript and Subscript numbers.
      </p>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r>
          <in><em>1/3</em>  <em>3/4</em>  <em>1/5</em>  <em>1337/5910</em></in>
          <to></to><out class="frac">1/3  3/4  1/5  1337/5910</out>
        </r>
      </t></tablex>
    </box>

    <box>
      <h3>Case alternates <q title='OpenType feature ID'>case</q></h3>
      <p>
        Switches out some glyphs to work better with capital letters and numbers.
      </p>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r>
          <in><em>(</em>Hello<em>)</em> <em>[</em>World<em>]</em> <em>{</em>9000<em>}</em></in>
          <to></to><out class="case">(Hello) [World] {9000}</out>
        </r>
        <r><in>SCHOOL <em>@</em> RUN</in><to></to><out class="case">SCHOOL @ RUN</out></r>
        <r><in>3 <em>+</em> 9 <em>=</em> 12 <em>*</em> 1</in><to></to><out class="case">3 + 9 = 12 * 1</out></r>
        <r><in><em>*</em> <em>+</em> <em>÷</em> <em>±</em> <em>×</em> <em>=</em> <em>≠</em> <em>•</em></in><to></to><out class="case">* + ÷ ± × = ≠ •</out></r>
        <r><in><em>→</em> <em>←</em> <em>⟶</em> <em>⟵</em> <em>−</em> <em>-</em> <em>–</em> <em>—</em> <em>:</em></in><to></to><out class="case">→ ← ⟶ ⟵ − - – — :</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Stylistic set 1: Alternate digits <q title='OpenType feature ID'>ss01</q></h3>
      <p>
        An alternate style of digits.
        Note that individual digit styles can be cherry-picked using the cvXX
        features.
      </p>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r>
          <in><em>1</em>23<em>4</em>5<em>6</em>78<em>9</em>0</in>
          <to></to><out class="ss01">1234567890</out>
        </r>
        <r><in><em>1</em></in><to></to><out class="ss01">1</out></r>
        <r><in><em>4</em></in><to></to><out class="ss01">4</out></r>
        <r><in><em>6</em></in><to></to><out class="ss01">6</out></r>
        <r><in><em>9</em></in><to></to><out class="ss01">9</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Stylistic set 2: Disambiguation <q title='OpenType feature ID'>ss02</q></h3>
      <p>
        Alternate glyph set that decreases ambiguity.
      </p>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>WP<em>0</em>AC2A9XJS1<em>0</em>12O9</in><to></to><out class="ss02">WP0AC2A9XJS1012O9</out></r>
        <r><in>I<em>ll</em>ega<em>l</em></in><to></to><out class="ss02">Illegal</out></r>
        <r><in>βeta <em>ß</em>eta Busine<em>ß</em></in><to></to><out class="ss02">βeta ßeta Busineß</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Discretionary ligatures <q title='OpenType feature ID'>dlig</q></h3>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in><em>¡¿</em>What<em>?!</em></in><to></to><out class="dlig">¡¿What?!</out></r>
        <r><in><em>¿¡</em>What<em>!?</em></in><to></to><out class="dlig">¿¡What!?</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Slashed zero <q title='OpenType feature ID'>zero</q></h3>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in><em>0</em>123</in><to></to><out class="zero">0123</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Character variants <q title='OpenType feature ID'>cvXX</q></h3>
      <p>
        Allows cherry-picking alternate characters.
      </p>
      <tablex><t>
        <h><name>Feature&nbsp;&nbsp;</name><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><name>cv01</name><in>1</in><to></to><out class="cv01">1</out></r>
        <r><name>cv02</name><in>4</in><to></to><out class="cv02">4</out></r>
        <r><name>cv03</name><in>6</in><to></to><out class="cv03">6</out></r>
        <r><name>cv04</name><in>9</in><to></to><out class="cv04">9</out></r>
        <r><name>cv05</name><in>l ł ƚ ɫ ɬ ŀ ĺ ļ ľ ḷ ḹ ḻ ḽ</in><to></to><out class="cv05">l ł ƚ ɫ ɬ ŀ ĺ ļ ľ ḷ ḹ ḻ ḽ</out></r>
        <r><name>cv06</name><in>r ɽ ɍ ɼ ŕ ŗ ř ȑ ȓ ṙ ṛ ṝ ṟ</in><to></to><out class="cv06">r ɽ ɍ ɼ ŕ ŗ ř ȑ ȓ ṙ ṛ ṝ ṟ</out></r>
        <r><name>cv07</name><in>ß</in><to></to><out class="cv07">ß</out></r>
      </t></tablex>
    </box>

    <box>
      <h3>Capital Spacing <q title='OpenType feature ID'>cpsp</q></h3>
      <p>
        Slightly increases letter spacing for increased legibility of
        capital letters. Note: It's usually better to set letter-spacing
        (aka tracking) manually instead of using this feature. It's here
        mainly for completeness.
      </p>
      <tablex><t>
        <h><in>Disabled</in><to></to><out>Enabled</out></h>
        <r><in>FOREVER IMMATERIAL</in><to></to><out class="cpsp">FOREVER IMMATERIAL</out></r>
        <r><in>TORSCHLUẞPANIK</in><to></to><out class="cpsp">TORSCHLUẞPANIK</out></r>
      </t></tablex>
    </box>

  </boxes>

  <p>
    Additional features, not highlighted above:
    <q title='OpenType feature ID'>locl</q>,
    <q title='OpenType feature ID'>aalt</q>,
    <q title='OpenType feature ID'>ccmp</q>,
    <q title='OpenType feature ID'>ordn</q> and
    <q title='OpenType feature ID'>salt</q>,
  </p>

  <p>&nbsp;</p>

  <h2 class="banner"><a href="glyphs/">Browse all glyphs -></a></h2>
</div></div>

<div class="row-divider"></div>

<div class="row"><div>
  <h2><a id="story" href="#story">The story behind Inter UI</a></h2>
  <p>
  Inter UI started out in late 2016 as an experiment to build a perfectly
  pixel-fitting font at a specific small size (11px.) The idea was that
  by crafting a font in a particular way, with a particular coordinate system
  (Units Per EM), and for a particular target rasterization size (11), it would
  be possible to get the best of both sharpness and readability.
  </p>
  <p>
  However after a few months of using an early version of Inter UI, it dawned
  on everyone exposed to the test that this approach had some serious real-world
  problems. Most notably that it was really hard to read longer text. Because of
  the pixel-aligning nature of that approach, the font took an almost
  <a href="https://www.figma.com/file/HPqDViSCB8fAWuxaV2ousFMv">mono-spaced appearance</a>,
  making it really easy to read numbers, punctuation and very short
  words, but eye-straining to read anything longer.
  </p>
  <p>
  The project was rebooted with a different approach, sticking with the
  specific UPM, but crafting glyphs and kerning in a way that made for
  more variation in the rhythm and smoother vertical and horizontal stems.
  As Inter UI was being developed, it was tested on an internal version of
  <a href="https://www.figma.com/">Figma</a>—where the author of Inter UI works as a designer—and slowly improved upon based on experience and feedback.
  </p>

  <p>&nbsp;</p>

  <h2><a id="status" href="#status">Current status &amp; usability</a></h2>
  <p>
  Inter UI works great for Latin text and pretty well for 
  Cyrillic. There's still some work to be done on Cyrillic and
  <a href="https://github.com/rsms/inter/blob/master/CONTRIBUTING.md">contributions are warmly welcomed</a>. The playground contains <a href="lab/?sample=Body%20text%201&size=16">a lot of samples</a>, including some common <a href="lab/?sample=Kerning%20body%20multi-lang&size=16">non English-language words in the playground.</a>
  </p>

  <p>
  Please refer to the <a href="glyphs/">glyph repertoire</a>
  for an overview of currently-available glyphs and their quality.
  </p>

  <p>&nbsp;</p>

  <h2><a id="faq" href="#faq">FAQ</a></h2>
  <ul class="faq">

    <li class="q" id="faq-using-features">
      How do I enable and disable font features?
    </li>
    <li class="a">
      In web browsers you'll want to use
      <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/font-feature-settings"><q>font-feature-settings</q></a>.
      In Figma you can access features via the
      <a href="https://help.figma.com/text/opentype-features">Advanced Typography panel.</a>
      In Illustrator, Photoshop and friends, you can access features via the
      <a href="https://helpx.adobe.com/illustrator/using/special-characters.html#opentype_panel_overview">Characters and OpenType panels.</a>
      Sketch doesn't provide a UI for configuring font features, but there's
      <a href="https://sketchtalk.io/discussion/comment/1478/#Comment_1478">a workaround using macOS's native font UI.</a>
    </li>

    <li class="q" id="faq-unhinted-vs-hinted">
      What is the difference between "unhinted" and "hinted" font files?
    </li>
    <li class="a">
      The font files in the "hinted" folders have additional data in them
      for assisting
      <a href="https://en.wikipedia.org/wiki/ClearType">ClearType</a>,
      the text rasterizer used by Microsoft Windows (and some Linux distributions.)
      You want to use the "hinted" fonts only if you are targeting Windows users
      <em>and</em> prefer the different look of these "hinted" fonts.
      Additionally, hinting data makes the font files larger, so if you are
      using Inter UI on websites, the extra size of these files is another
      consideration to make.
      <a href="https://www.typotheque.com/articles/hinting">
      This article explains hinting at a greater length.</a>
    </li>


    <li class="q" id="faq-cdn">
      How reliable are the fonts served from rsms.me/inter? Is it on a CDN?
    </li>
    <li class="a">
      rsms.me/inter is backed by GitHub's server network and distributed
      globally on the CloudFlare CDN, making usage of
      <q>https://rsms.me/inter/inter-ui.css</q> and associated font
      files very reliable and fast throughout the world. 
    </li>

    <li class="q" id="faq-contribute">
      Can I help with improving Inter UI?
    </li>
    <li class="a">
      Yes you can! Inter UI is an open-source project, meaning the source
      code—or "source design" if you will—that is used to build the font files
      <a href="https://github.com/rsms/inter">are freely available</a> to improve upon.
      Font making requires a fair bit of technical work and
      depending on what you'd like to do, some things might be more fun
      depending on your technical skills.
      The <a href="https://github.com/rsms/inter/blob/master/CONTRIBUTING.md">"Contributing" document</a> is a great place to start. The document outlines where
      you can have the biggest impact, how things are setup and how to get
      started.
    </li>

    <li class="q" id="faq-start-date">
      This website claims work started in 2016, but the git repository's log says it started later?
    </li>
    <li class="a">
      Inter UI was developed in an a private, internal git repository
      starting in November 2016, prior to being published on August 22, 2017.
      Between November 2016 and August 2017, there were
      <num>2&#x2006;990&#x2006;150</num> line edits made across 247 versions.
      The reason the public GitHub repository does not reflect this is the
      fact that the project was initially only internal at the company where
      the author works and had some sensitive information "checked in",
      like AWS server details and internal author identity in
      all commit messages. Maybe one day we can write an elaborate git
      filter-branch program and convert the filter the old repository to make
      it public, but what would be the point of that?&nbsp; :—)
    </li>

    <li class="q" id="faq-contact">
      I've made a cool thing that uses Inter UI, can I share it with you?
      &nbsp;<dem>or</dem>
    </li>
    <li class="q">
      I have a different question
    </li>
    <li class="a">
      Reach out on <a href="https://twitter.com/rsms">Twitter (@rsms)</a> or over <a href="mailto:rasmus@notion.se">email</a>
    </li>


  </ul>

</div></div>


<div class="row"><div>
  — <a href="https://twitter.com/rsms" class="plain">@rsms</a>
</div></div>

<script>

// FAQ anchors
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for (i = 0; i < av.length; ++i) {
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  tn = document.createTextNode('Q  ')
  e.insertBefore(tn, e.firstChild)
  id = e.id
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    // a.id = id
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})();


// dynamic metrics calculator
(function(){

var hiddenTextInput = $('#hidden-text-input')
var fontSizeEl = $('#dynmet-font-size')
var trackingEl = $('#dynmet-tracking')
var unitEl = $('#dynmet-unit')

var unitFormatters = [
  ['em', 'em', function(fontSize, tracking) {
    return tracking.toFixed(3)
  }],
  ['px', 'px', function(fontSize, tracking) {
    return (fontSize * tracking).toFixed(1)
  }],
  ['%', 'percent', function(fontSize, tracking) {
    return (tracking * 100).toFixed(1)
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]
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  } else if (fontSize > 999) {
    fontSizeEl.value = fontSize = 999
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  trackingEl.value = unitFormatter(fontSize, tracking)
}

function toggleUnit() {
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  trackingEl.classList.add(u[1])
  unitFormatter = u[2]
  unitEl.innerText = unit
  updateTracking()
}

function onPointerdownUnit(ev) {
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    ev.preventDefault()
    ev.stopPropagation()
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}

function onPointerdownTracking(ev) {
  if (ev) {
    ev.preventDefault()
    ev.stopPropagation()
  }
  hiddenTextInput.value = trackingEl.value + unitEl.innerText
  hiddenTextInput.select()
  document.execCommand("copy")
  trackingEl.select()
  HUDNotification.show('Copied to clipboard')
}

var passiveListener = { passive: true, capture: false }
var activeListener = { capture: true }

fontSizeEl.addEventListener('input', updateTracking, passiveListener)
fontSizeEl.addEventListener('change', updateTracking, passiveListener)

unitEl.addEventListener('pointerdown', onPointerdownUnit, activeListener)
unitEl.addEventListener('mousedown', onPointerdownUnit, activeListener)

trackingEl.addEventListener('pointerdown', onPointerdownTracking, activeListener)
trackingEl.addEventListener('mousedown', onPointerdownTracking, activeListener)

updateTracking()

})();</script>