openproject/app/views/browser/_unsupported_browser.html.erb

<div id="unsupported-browser-warning" class="top-shelf unsupported-browser-warning--pane">
  <p>
    <span title="<%= t('unsupported_browser.close_warning') %>" class="icon3 icon-warning unsupported-browser-warning--icon"></span>
    <strong><%= t('unsupported_browser.title') %></strong>

    <%= t('unsupported_browser.message') %>

    <a href="https://www.openproject.org/open-source/download/systemrequirements/"
       target="_blank">
      <%= t('unsupported_browser.update_message') %>
    </a>
  </p>
</div>

<%= nonced_javascript_tag do %>
  // Hide initially
  var message = document.getElementById('unsupported-browser-warning');

  try {
    var hidden = window.localStorage.getItem('unsupported-browser-warning-ignore') === '1';
    if (hidden) {
      message.style.display = 'none';
    }
  } catch (e) {
    console.error('Failed to access your browsers local storage.');
  }

  // Click handler to hide
  var span = document.querySelector('.unsupported-browser-warning--icon');
  span.onclick = function() {
    message.style.display = 'none';
    try {
      window.localStorage.setItem('unsupported-browser-warning-ignore', '1');
    } catch (e) {
      console.error('Failed to access your browsers local storage.');
    }
  };
<% end %>