app/views/application/_spinner.html.erb
<!-- SVG spinner by Aurer -->
<!-- https://codepen.io/aurer/pen/jEGbA -->
<div class="spinner">
<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
width="33px" height="33px" viewBox="0 0 50 50" style="enable-background:new 0 0 50 50;" xml:space="preserve">
<path fill="#FFF" d="M25.251,6.461c-10.318,0-18.683,8.365-18.683,18.683h4.068c0-8.071,6.543-14.615,14.615-14.615V6.461z">
<animateTransform attributeType="xml"
attributeName="transform"
type="rotate"
from="0 25 25"
to="360 25 25"
dur="0.6s"
repeatCount="indefinite"/>
</path>
</svg>
</div>