font

font:
  1.2rem "Fira Sans",
  sans-serif;

font:
  italic 1.2rem "Fira Sans",
  serif;

font: italic small-caps bold 16px/2 cursive;

font: small-caps bold 24px/1 sans-serif;

font: caption;

<section id="default-example">
  <p id="example-element">
    London. Michaelmas term lately over, and the Lord Chancellor sitting in
    Lincoln's Inn Hall. Implacable November weather. As much mud in the streets
    as if the waters had but newly retired from the face of the earth, and it
    would not be wonderful to meet a Megalosaurus, forty feet long or so,
    waddling like an elephantine lizard up Holborn Hill.
  </p>
</section>

@font-face {
  font-family: "Fira Sans";
  src:
    local("FiraSans-Regular"),
    url("/shared-assets/fonts/FiraSans-Regular.woff2") format("woff2");
  font-weight: normal;
  font-style: normal;
}

@font-face {
  font-family: "Fira Sans";
  src:
    local("FiraSans-Italic"),
    url("/shared-assets/fonts/FiraSans-Italic.woff2") format("woff2");
  font-weight: normal;
  font-style: italic;
}

section {
  margin-top: 10px;
  font-size: 1.1em;
}

/* font-size font-family */
font: 1.2em "Fira Sans", sans-serif;

/* font-size/line-height font-family */
font: 1.2em/2 "Fira Sans", sans-serif;

/* font-style font-weight font-size font-family */
font: italic bold 1.2em "Fira Sans", sans-serif;

/* font-stretch font-variant font-size font-family */
font: ultra-condensed small-caps 1.2em "Fira Sans", sans-serif;

/* system font */
font: caption;

/* Set the font size to 12px and the line height to 14px.
   Set the font family to sans-serif */
p {
  font: 12px/14px sans-serif;
}

/* Set the font size to 80% of the parent element
   or default value (if no parent element present).
   Set the font family to sans-serif */
p {
  font: 80% sans-serif;
}

/* Set the font weight to bold,
   the font-style to italic,
   the font size to large,
   and the font family to serif. */
p {
  font: bold italic large serif;
}

/* Use the same font as the status bar of the window */
p {
  font: status-bar;
}

<p>
  Change the radio buttons below to see the generated shorthand and its effect.
</p>
<form action="createShortHand()">
  <div class="cf">
    <div class="setPropCont">
      font-style<br />
      <input
        type="radio"
        id="font-style-none"
        name="font_style"
        checked=""
        value="" />
      <label for="font-style-none">none</label><br />
      <input
        type="radio"
        id="font-style-normal"
        name="font_style"
        value="normal" />
      <label for="font-style-normal">normal</label><br />
      <input
        type="radio"
        id="font-style-italic"
        name="font_style"
        value="italic" />
      <label for="font-style-italic">italic</label><br />
      <input
        type="radio"
        id="font-style-oblique"
        name="font_style"
        value="oblique" />
      <label for="font-style-oblique">oblique</label>
    </div>

    <div class="setPropCont">
      font-variant<br />
      <input
        type="radio"
        id="font-variant-none"
        name="font_variant"
        checked=""
        value=" " />
      <label for="font-variant-none">none</label><br />
      <input
        type="radio"
        id="font-variant-normal"
        name="font_variant"
        value="normal" />
      <label for="font-variant-normal">normal</label><br />
      <input
        type="radio"
        id="font-variant-small-caps"
        name="font_variant"
        value="small-caps" />
      <label for="font-variant-small-caps">small-caps</label>
    </div>

    <div class="setPropCont">
      font-weight<br />
      <input type="radio" id="font-weight-none" name="font_weight" value="" />
      <label for="font-weight-none">none</label><br />
      <input
        type="radio"
        id="font-weight-normal"
        checked=""
        name="font_weight"
        value="400" />
      <label for="font-weight-normal">normal</label><br />
      <input
        type="radio"
        id="font-weight-bold"
        name="font_weight"
        value="700" />
      <label for="font-weight-bold">bold</label>
    </div>

    <div class="setPropCont">
      font-size<br />
      <input type="radio" id="font-size-12px" name="font_size" value="12px" />
      <label for="font-size-12px">12px</label><br />
      <input
        type="radio"
        id="font-size-16px"
        name="font_size"
        value="16px"
        checked="" />
      <label for="font-size-16px">16px</label><br />
      <input type="radio" id="font-size-24px" name="font_size" value="24px" />
      <label for="font-size-24px">24px</label>
    </div>

    <div class="setPropCont">
      line-height<br />
      <input
        type="radio"
        id="line-height-none"
        name="line_height"
        checked=""
        value="" />
      <label for="line-height-none">none</label><br />
      <input
        type="radio"
        id="line-height-1.2"
        name="line_height"
        value="/1.2" />
      <label for="line-height-1.2">1.2</label><br />
      <input type="radio" id="line-height-3" name="line_height" value="/3" />
      <label for="line-height-3">3</label>
    </div>
    <br />

    <div class="setPropCont fontfamily">
      font-family<br />
      <input
        type="radio"
        id="font-family-courier"
        name="font_family"
        checked=""
        value="courier" />
      <label for="font-family-courier">courier</label><br />
      <input
        type="radio"
        id="font-family-serif"
        name="font_family"
        value="serif" />
      <label for="font-family-serif">serif</label><br />
      <input
        type="radio"
        id="font-family-sans-serif"
        name="font_family"
        value="sans-serif" />
      <label for="font-family-sans-serif">sans-serif</label><br />
      <input
        type="radio"
        id="font-family-arial"
        name="font_family"
        value="arial" />
      <label for="font-family-arial">Arial</label><br />
      <input
        type="radio"
        id="font-family-monospace"
        name="font_family"
        value="monospace" />
      <label for="font-family-monospace">monospace</label><br />
      <input
        type="radio"
        id="font-family-cursive"
        name="font_family"
        value="cursive" />
      <label for="font-family-cursive">cursive</label><br />
      <input
        type="radio"
        id="font-family-fantasy"
        name="font_family"
        value="fantasy" />
      <label for="font-family-fantasy">fantasy</label><br />
      <input
        type="radio"
        id="font-family-system-ui"
        name="font_family"
        value="system-ui" />
      <label for="font-family-system-ui">system-ui</label><br />
    </div>
  </div>

  <div class="cf propInputs">
    <div class="propInputCont tar">font :</div>
    <div class="propInputCont">
      <input type="text" class="curCss" id="input_font_style" /><br />
      font-style <br />
      optional
    </div>
    <div class="propInputCont">
      <input type="text" class="curCss" id="input_font_variant" /> <br />
      font-variant <br />
      optional
    </div>
    <div class="propInputCont">
      <input type="text" class="curCss" id="input_font_weight" /> <br />
      font-weight <br />
      optional
    </div>
    <div class="propInputCont">
      <input type="text" class="curCss mandatory" id="input_font_size" /> <br />
      font-size <br />
      mandatory
    </div>
    <div class="propInputCont">
      <input type="text" class="curCss" id="input_line_height" /> <br />
      line-height <br />
      optional
    </div>
    <div class="propInputCont">
      <input type="text" class="curCss mandatory" id="input_font_family" />
      <br />
      font-family <br />
      mandatory
    </div>
  </div>
</form>

<div class="fontShortHand">This is some sample text.</div>
<br /><br /><br /><br /><br /><br />

body,
input {
  font: 14px "Arial";
  overflow: hidden;
}

.propInputCont {
  float: left;
  text-align: center;
  margin-right: 5px;
  width: 80px;
}

.setPropCont {
  float: left;
  margin-right: 5px;
  width: 120px;
}

.propInputs,
.setPropCont {
  margin-bottom: 1em;
}

.curCss {
  border: none;
  border-bottom: 1px solid black;
  text-align: center;
  width: 80px;
}

.mandatory {
  border-bottom-color: red;
}

.cf::before,
.cf::after {
  content: " ";
  display: table;
}

.cf::after {
  clear: both;
}

.tar {
  width: 40px;
  text-align: right;
}
.fontfamily {
  display: inline-block;
}

const textAreas = document.getElementsByClassName("curCss");

function getProperties() {
  return (
    `${getCheckedValue("font_style")} ` +
    `${getCheckedValue("font_variant")} ` +
    `${getCheckedValue("font_weight")} ` +
    `${getCheckedValue("font_size")}` +
    `${getCheckedValue("line_height")} ` +
    `${getCheckedValue("font_family")}`
  );
}

function getCheckedValue(radioName) {
  const radios = document.forms[0].elements[radioName];
  for (const radio of radios) {
    if (radio.checked) {
      const curElemName = `input_${radioName}`;
      const curElem = document.getElementById(curElemName);
      curElem.value = radio.value;

      return radio.value;
    }
  }
}

function setCss() {
  injectCss(getProperties());
}

function injectCss(cssFragment) {
  const old = document.body.getElementsByTagName("style");
  if (old.length > 1) {
    old[1].parentElement.removeChild(old[1]);
  }
  css = document.createElement("style");
  css.textContent = `.fontShortHand{font: ${cssFragment}}`;
  document.body.appendChild(css);
}

setCss();

document.querySelectorAll("input[type='radio']").forEach((el) => {
  el.addEventListener("change", setCss);
});