Todo subitem

<main>
    <header>
      <h1>Todo List</h1>
    </header>
    <section>
      <ul>
        <li>
          <span>Groceries</span>
          <ul>
            <li><span>3 Tomatoes</span></li>
            <li><span>1 bunch of cherries</span></li>
            <li><span>6 onions</span></li>
            <li><span>3 heads of garlic</span></li>
            <li><span>1 bag spring mix</span></li>
          </ul>
        </li>
        <li><span>Cancel gym membership</span></li>
        <li><span>Clean gutters</span></li>
        <li><span>Take package to the post office</span></li>
        <li><span>Call Avery about Ali's party (afternoon)</span></li>
        <li><span>Sort recycling & put out trash</span></li>
      </ul>
    </section>
    <footer>
      <form class="wrapper" name="addToList">
        <input type="text" placeholder="Add more" />
        <button title="Add">+</button>
      </form>
      <small>Use the ">" to add a subitem</small>
    </footer>
  </main>

* {
  box-sizing: border-box;
}
:root {
  --gapSize: 0.6rem;
  --barSize: 0.3rem;
  --bulletSize: 0.6rem;
  --altBg: linear-gradient(#f7ff00, #db36a4);
  --bg: linear-gradient(#f0c, #7303c0, #339);
}
body {
  display: flex;
  height: 100vh;
  align-items: center;
  justify-content: center;
  background: #212121;
  font-family: 'Rubik';
}
main {
  position: relative;
  box-shadow: 0 5px 15px -5px #000;
  background: #fff;
  border-radius: 10px;
  overflow: hidden;
}
header {
  position: relative;
  background: #fff;
  padding: 1.4rem 0;
  box-shadow: 0 1px 10px rgba(0,0,0,0.2);
  z-index: 3;
}
header h1 {
  margin: 0;
  text-align: center;
  background: var(--bg) fixed;
  background-clip: text;
  -webkit-background-clip: text;
  color: transparent;
}
section {
  height: 50vh;
  overflow: scroll;
}
section ul {
  margin: 0;
  padding: 0;
  list-style: none;
}
section ul > li {
  position: relative;
  padding: var(--gapSize) 1.4rem;
  --currentBg: #fff;
}
section ul > li span {
  background: var(--altBg) fixed;
  background-clip: text;
  -webkit-background-clip: text;
  transition: all 200ms ease-in-out;
}
section ul > li:hover > span {
  color: transparent;
}
section ul > li:nth-child(odd) {
  background: #f5f5f5;
  --currentBg: #f5f5f5;
}
section ul > li::before {
  content: '';
  display: inline-block;
  width: var(--bulletSize);
  height: var(--bulletSize);
  border-radius: var(--bulletSize);
  margin-right: var(--bulletSize);
  vertical-align: middle;
  background: var(--bg) fixed;
}
section ul > li::after {
  content: '';
  position: absolute;
  top: 0;
  bottom: calc(-1 * (var(--bulletSize) + var(--gapSize)));
  left: calc(1.4rem + (var(--bulletSize) / 2) - (var(--barSize) / 2));
  width: var(--barSize);
  background: var(--bg) fixed;
  border-radius: 0 0 10px 10px;
  z-index: 1;
}
section ul > li:first-child::after {
  top: calc(var(--bulletSize) + var(--gapSize));
}
section ul > li:last-child::after {
  bottom: 2.7rem;
}
section ul > li ul {
  position: relative;
  padding-top: var(--gapSize);
}
section ul > li ul::before {
  content: '';
  position: absolute;
  top: var(--gapSize);
  left: var(--barSize);
  width: calc(1.4rem - (var(--barSize) / 2));
  height: 1rem;
  background: linear-gradient(var(--currentBg), var(--currentBg)) padding-box, var(--bg) fixed border-box;
  border-width: var(--barSize) var(--barSize) 0 0;
  border-radius: 0 10px 0 0;
  border-style: solid;
  border-color: transparent;
}
section ul > li ul > li:nth-child(odd) {
  background: transparent;
  z-index: 1;
}
footer {
  position: relative;
  background: #fff;
  padding: 1.4rem;
  box-shadow: 0 1px 10px rgba(0,0,0,0.2);
  z-index: 3;
}
footer form {
  position: relative;
  margin-bottom: 0.2rem;
}
footer input {
  width: 100%;
  padding: 0.4rem 1rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  font-family: 'Rubik';
}
footer input:focus {
  outline: 0;
  box-shadow: 0 0 5px #ec38bc;
}
footer button {
  position: absolute;
  top: 0px;
  bottom: 0px;
  right: 0px;
  aspect-ratio: 1;
  background: var(--bg) fixed;
  border: none;
  border-radius: 0 6px 6px 0;
  color: #fff;
}
footer small {
  font-style: italic;
  color: #78909c;
}

const form = document.querySelector("form[name=addToList]");
const input = document.querySelector("form[name=addToList] input");
const section = document.querySelector("section");
const list = document.querySelector("section > ul");

const addNameToList = function (e) {
	e.preventDefault();
	if (!input.value) return false;

	const text = document.createTextNode(input.value);
	const newItem = document.createElement("li");
	const itemContent = document.createElement("span");

	itemContent.appendChild(text);
	newItem.appendChild(itemContent);

	if (input.value.startsWith(">")) {
		itemContent.textContent = itemContent.textContent.replace(">", "");

		const lastItem = document.querySelector("section > ul > li:last-child");
		const subList = lastItem.querySelector("ul") || document.createElement("ul");

		lastItem.appendChild(subList);
		subList.appendChild(newItem);
	} else {
		list.appendChild(newItem);
	}

	input.value = "";
	section.scrollTo({ top: section.scrollHeight, behavior: "smooth" });
};

form.addEventListener("submit", addNameToList);