add to spinner to loading page

themes/custom/shriupahar/templates/layout
html.html.twig 


<body{{ attributes.addClass(body_classes) }}>
    <div id="loading">
      <div class="d-flex justify-content-center align-items-center h-100">
          <img class="logo" src="/themes/custom/shriupahar/logo.svg" alt="logo" width="50px">
      </div>
    </div>