JSFiddle - React, Tailwind, and code Playground

HTML

<html>
  <head>
    <script type='text/javascript'>
      function has24HourPassed(key) {
        var storeval = localStorage.getItem(key);
        if (!storeval) return true;    /*  nothing stored in storage  */
        var T24_HOUR = 24 * 60 * 60 * 1000;
        if ((new Date - new Date(storeval)) < T24_HOUR) return false;        
        localStorage.removeItem(key);  /*  24 hours passed so we can remove stored date  */
        return true;
      }
      (function(d) {
        if (has24HourPassed('al-news')) {
          d.classList.add('al-news');
        }
        if (has24HourPassed('al-maintenance')) {
          d.classList.add('al-maintenance');
        }
      })(document.documentElement);
    </script>
  </head>

  <body>
    <article class="alert-box" id="alert-box-news">
      <h1>News Alerts</h1>
      <p>text text text text text text text text text text text text text text</p>
      <a class="alert-box-close" id="close-alert-box-news">
        <img src="http://i.imgur.com/czf8yas.png" height="25" width="25" alt="">
      </a>
    </article>

    <article class="alert-box" id="alert-box-maintenance">
      <h1>Site Maintenance</h1>
      <p>text text text text text text text text text text text text text text</p>
      <a class="alert-box-close" id="close-alert-box-maintenance">
        <img src="http://i.imgur.com/czf8yas.png" height="25" width="25" alt="">
      </a>
    </article>

    <button>For this demo - to clear local storage</button>

  </body>

</html>

CSS

.alert-box {
  display: none;
  width: 50vw;
  position: relative;
  margin: 20px auto;
  border: 1px solid black;
}

.alert-box-close {
  position: absolute;
  top: -12px;
  right: -12px;
  cursor: pointer;
}

.al-news #alert-box-news,
.al-maintenance #alert-box-maintenance {
  display: block;
}

JavaScript

var alerts = document.querySelectorAll('.alert-box-close');
for (var i = 0; i < alerts.length; i++) {
  alerts[i].addEventListener('click', function(e) {
    var boxtype = e.target.parentElement.id.split('-').pop();
    document.getElementById('alert-box-' + boxtype).style.display = "none";
    localStorage.setItem("al-" + boxtype, new Date());
  })
}

document.querySelector('button').addEventListener('click', function(e) {
  localStorage.clear();
})