JSFiddle - React, Tailwind, and code Playground

HTML

<div class="div_frame">

        <div class="list_title">To-Do List</div>

        <div class="list_in">
            <input class="list_input" id="list_input" type="text" placeholder="輸入代辦事項。。。">
            <select class="select_type" id="select_type" onchange="select_type()">
              <option style="background:#ffffffa3;" value="normal">一般</option>
              <option style="background:#ffd561a3;" value="important">重要</option>
              <option style="background:#ff7d7da3;" value="urgent">緊急</option>
          </select>
            <button class="list_btn" onclick="add_list()">add</button>
        </div>

        <div class="list_out">

            <ul class="list_ul" id="list_ul">
                <!-- 清單位置 -->
            </ul>

        </div>

        <div class="list_remit">
          <button class="remit_btn" onclick="list_remit()">remit</button>
          <button class="save_btn" onclick="list_save()">save</button>
        </div>

    </div>

CSS

.div_frame{
    width:500px;
    /*height: 500px;*/
    border-radius:20px;
    border:0;
    background-color:#fbf470;
}

.list_title{
    width: 500px;
    height: 50px;
    line-height: 50px;
    text-align: center;
    font-size: 20px;
    font-family: Comic Sans MS;

    /*border-style:solid;*/
}

.list_in{
    width: 500px;
    height: 50px;
    font-size: 20px;
    font-family: Comic Sans MS;

    display: flex;
    justify-content:center;
    align-items: center;

    /*border-style:solid;*/
}

.list_input{
    width: 300px;
    height: 30px;

    border-radius: 10px 0 0 10px;
    border:0;
    outline:none;
    
    font-family: Comic Sans MS , Microsoft JhengHei;
    text-indent: 10px;  /*輸入文字邊距*/
    transition: 0.1s;
}

.list_btn{
    width: 50px;
    height: 30px;
    box-sizing: content-box;

    border-radius: 0 10px 10px 0;
    border:0;
    
    font-family: Comic Sans MS;
    transition: 0.1s;
}
.list_btn:hover , .list_input:hover{
    box-shadow: 0px 0px 2px 2px #b1b1b1;
    z-index: 1;
}
.list_btn:active{
    box-shadow: inset 0px 0px 3px 3px #b1b1b1;
}

.list_out{
    width: 500px;
    /*height: 300px;*/
    font-size: 20px;

    font-family: Comic Sans MS , Microsoft JhengHei;

    display: flex;
    justify-content:center;

    /*border-style:solid;*/
}

.list_ul{
    list-style-type:none;   /*消除點*/
    padding-left: 0;        /*消除原本點的位置*/
}

.list_ul li{
    width: 350px;
    margin-top: 10px;       /*li之間分隔*/


    display: flex;
    justify-content: flex-end;

    
    border-bottom: 1px solid #000;
    /*background:#ffffffa3;*/
}

.list_ul li span{
    margin-right: auto;
    /*flex: 1;*/
    font-family: Comic Sans MS , Microsoft JhengHei;
}

.mark_complete{
    color: red;
    flex: 1;
    display: none;
}

.list_ul li button{

    color: red;
    background-color: transparent;
    border: 0;
    font-family: Comic Sans MS , Microsoft JhengHei;
    transition: 0.3s;
}
.list_ul li button:hover{
    font-weight: bold;
    transform:...

JavaScript

var sort = 0; //目前清單內容數量

if (localStorage.getItem("save_data")) {

  var save_data = JSON.parse(localStorage.getItem("save_data"));

  sort = save_data[0].sort;

  for (var x of save_data) {

    var list_ul = document.querySelector('#list_ul'); //選取ul

    var creat_li = document.createElement('li'); //創建li
    var creat_sapn = document.createElement('span'); //待辦事項
    var creat_sapn2 = document.createElement('span'); //隱藏的✔
    var creat_btn2 = document.createElement('button'); //✔按鈕
    var creat_btn = document.createElement('button'); //刪除按鈕

    creat_sapn.setAttribute('id', 'span' + (x.number - 1)); //新增span id=span[]

    creat_sapn.textContent = x.number + '.' + x.content;
    creat_btn.textContent = "X";
    creat_btn.onclick = remove_list;


    list_ul.append(creat_li);

    creat_li.append(creat_sapn);

    creat_li.append(creat_sapn2);
    creat_sapn2.className = "mark_complete";
    creat_sapn2.textContent = "✔";

    creat_li.append(creat_btn2);
    creat_btn2.onclick = mark_complete;
    creat_btn2.textContent = "✔"

    creat_li.append(creat_btn);


    if (x.type == "normal_type") {
      creat_li.className = "normal_type"
    } else if (x.type == "important_type") {
      creat_li.className = "important_type"
    } else if (x.type == "urgent_type") {
      creat_li.className = "urgent_type"
    }

  }

}

function add_list() {

  var add_text = document.querySelector('#list_input').value; //取輸入文字
  var select_type = document.querySelector('#select_type').value; //一般.重要.緊急
  var list_ul = document.querySelector('#list_ul'); //選取ul

  var creat_li = document.createElement('li'); //創建li
  var creat_sapn = document.createElement('span'); //待辦事項
  var creat_sapn2 = document.createElement('span'); //隱藏的✔
  var creat_btn2 = document.createElement('button'); //✔按鈕
  var creat_btn = document.createElement('button'); //刪除按鈕

  creat_sapn.setAttribute('id', 'span' + (sort)); //新增span id=span[]

  creat_sapn.textContent = (sort + 1).toString() + '.' +...