JSFiddle - React, Tailwind, and code Playground

HTML

<div class='container'>
  <div class="wrap">
    <h1>Список задач</h1>
    <div class="inp-wrap">
      <input class='task' type="text" placeholder='Введите текст задачи'>
      <button class='plus'>+</button>
    </div>
    <div class='task-container' id='task-container'>
     
    </div>
  </div>
</div>

CSS

* {
  box-sizing:border-box;
}
.container {
  max-width: 500px;
  margin: 0 auto;
}
h1 {
  background-color: orange;
  text-align: center;
  border-radius:10px 10px 0 0;
  color: #fff;
}
.inp-wrap {
  margin-bottom: 20px;
  display: flex;
  padding: 10px;
}
.plus {
  margin-left: 15px;
  border: none;
  border-radius: 20px;
  background: lightgreen;
  font-size: 30px;
  padding: 0 8px;
  outline: none;
  color: #fff;
  &:hover {
    color: red;
    opacity: 0.8;
  }
}
.task {
  width: 100%;
  padding: 5px;
  font-size: 16px;
}
.task-item {
  display: flex;
  align-items: center;
  max-width: 90%;
  font-size: 18px;
}
#scales {
  margin-right: 10px
}
.task-wrap {
  display: flex;
  align-items: center;
  background: gainsboro;
  margin-bottom: 10px;
  padding: 10px;
  &:nth-child(2n) {
    background: #fff;
  }
}
.task-wrap-check {
  text-decoration: line-through;
}
.minus {
  margin-left: auto;
  border: none;
  border-radius: 20px;
  background: lightgreen;
  font-size: 25px;
  padding: 0 12px;
  outline: none;
  color: #fff;
  &:hover {
    color: red;
    opacity: 0.8;
  }
}

JavaScript

let textVal = document.querySelector('.task')
let btnAdd = document.querySelector('.plus')
let taskCont = document.getElementById('task-container')
let btnDel = document.getElementsByClassName('minus')
let itemsV = taskCont.children

taskCont = localStorage.getItem('todoList');

function saveTodo(){
	localStorage.setItem('todoList',taskCont );
}

function addTask() {
  btnAdd.addEventListener('click', () => {
  taskCont.innerHTML += `
  	<div class='task-wrap' id='task-wrap'>
      <div class='task-item'>
        ${textVal.value}
      </div>
      <button class='minus'>-</button>
    </div>
  `
  textVal.value = ''
  remove()
  saveTodo()
 })
}

function remove() {
  for(let item of btnDel) {
    item.onclick = function() {
      item.parentElement.remove();
      saveTodo()
    }
  }
}

function isCheck() {
  taskCont.addEventListener('click', (e) => {
    let {target} = e
    if(target.classList.contains('task-wrap')){
      target.classList.toggle('task-wrap-check')
    }
    saveTodo()
  })
}

isCheck()
addTask()