JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <link
      rel="stylesheet"
      href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.0-2/css/all.min.css"
    />
    <link rel="stylesheet" href="style.css" />
  </head>
  <body>
    <div class="container">
      <table id="data_table">
        <thead>
          <tr>
            <th>#</th>
            <th>Date</th>
            <th>From</th>
            <th>To</th>
            <th>Wage</th>
            <th>Edit</th>
          </tr>
        </thead>
        <tbody id="tbody">
          <tr id="row">
            <td id="serial"></td>
            <td id="mydate"></td>
            <td id="from"></td>
            <td id="to"></td>
            <td id="wage"></td>
            <td id="edit">
              <i class="far fa-edit" id="editrow" onclick="edit_row(no)"
                ><input type="button"
              /></i>
              <i
                class="far fa-trash-alt"
                id="deleterow"
                onclick="delete_row(no)"
                ><input type="button"
              /></i>
              <i class="far fa-save"
                ><input
                  type="button"
                  id="saverow"
                  value="Save"
                  class="save"
                  onclick="save_row()"
              /></i>
            </td>
          </tr>
        </tbody>
      </table>
      <div class="hoursofwork">
        <label>From</label>
        <input type="time" placeholder="From" id="new_from" /> <label>To</label
        ><input type="time" placeholder="To" id="new_to" />
        <button id="btn" type="button" onclick="add_row(); getmyDate()">
          <i class="far fa-plus-square"></i>
        </button>
      </div>
    </div>

    <script src="app2.js"></script>
  </body>
</html>

CSS

body {
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  width: 100vw;
  height: 100vh;
}

.container {
  position: relative;
  width: 700px;
  border: 2px solid black;
  margin: 100px 0;
}

table {
  width: 100%;
  border-spacing: 0;
  counter-reset: serial;
}

th,
td {
  padding: 6px 12px;
  border: 1px solid black;
}

th {
  font-size: 1.5em;
  font-family: Arial, Helvetica, sans-serif;
  background: wheat;
}

th:nth-child(2) {
  width: 200px;
}

#date {
  width: 100px;
}

td {
  text-align: center;
  position: relative;
  font-size: 1em;
  font-family: fantasy;
}

td:first-child::before {
  counter-increment: serial;
  content: counter(serial);
}

#tbody #row {
  display: none;
}

td:nth-child(5) {
  padding: 0;
}

td input {
  width: 90%;
  font-size: 1em;
  border: none;
}

.far {
  cursor: pointer;
  margin: 0 5px;
}

.fa-edit {
  color: blue;
}

.fa-save {
  display: none;
}

.fa-trash-alt {
  color: red;
}

.employee,
.hoursofwork {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 55px;
  background: green;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: row;
}

.employee input,
.hoursofwork input {
  height: 25px;
  width: 150px;
  margin: 0 15px;
  font-size: 1.3em;
}

#btn {
  font-size: 2em;
  text-align: center;
  background: transparent;
  color: white;
  border: none;
  cursor: pointer;
}

label {
  font-size: 2em;
  color: white;
  font-family: fantasy;
}

JavaScript

var tbody = document.getElementById("tbody");
var btn = document.getElementById("btn");

//ADD ROWS//
function add_row() {
  if (tbody.rows.length > 20) {
    return;
  }
  new_from = document.getElementById("new_from").value;
  new_to = document.getElementById("new_to").value;

  var table = document.getElementById("data_table");
  var table_len = table.rows.length - 1;
  var row = (table.insertRow(table_len).outerHTML =
    "<tr id='row" +
    table_len +
    "'><td id='serial" +
    table_len +
    "'></td><td id='mydate" +
    table_len +
    "'></td><td id='from" +
    table_len +
    "'>" +
    new_from +
    "</td><td id='to" +
    table_len +
    "'>" +
    new_to +
    "</td><td id='wage" +
    table_len +
    "'></td><td><i class='far fa-edit' id='editrow" +
    table_len +
    "' onclick='edit_row(" +
    table_len +
    ")'></i> <i class= 'far fa-save' id='saverow" +
    table_len +
    "' onclick='save_row(" +
    table_len +
    ")'></i><i class='far fa-trash-alt' onclick='delete_row(" +
    table_len +
    ")'></i></td></tr>");

  document.getElementById("new_from").value = "";
  document.getElementById("new_to").value = "";
}

//EDIT ROWS//
function edit_row(no) {
  from = document.getElementById("from" + no);
  to = document.getElementById("to" + no);
  document.getElementById("editrow" + no).style.display = "none";
  document.getElementById("saverow" + no).style.display = "inline-block";
  from_data = from.innerHTML;
  to_data = to.innerHTML;

  from.innerHTML =
    "<input type='text' id='from_text" + no + "' value='" + from_data + "'>";
  to.innerHTML =
    "<input type='text' id='to_text" + no + "' value='" + to_data + "'>";
}

//SAVE ROWS//
function save_row(no) {
  var from_val = document.getElementById("from_text" + no).value;
  var to_val = document.getElementById("to_text" + no).value;

  document.getElementById("from" + no).innerHTML = from_val;
  document.getElementById("to" + no).innerHTML = to_val;

 ...