Exemplary template to change the loading template to replace the default loading bars that users will see when the WordPress + Office 365 plugin redirects them to Microsoft (see https://docs.wpo365.com/article/114-customize-the-loading-template for details)

loading-template.html

<style>
.lds-grid{display:inline-block;position:relative;width:80px;height:80px}.lds-grid div{position:absolute;width:16px;height:16px;border-radius:50%;background:#000;animation:lds-grid 1.2s linear infinite}.lds-grid div:nth-child(1){top:8px;left:8px;animation-delay:0s}.lds-grid div:nth-child(2){top:8px;left:32px;animation-delay:-.4s}.lds-grid div:nth-child(3){top:8px;left:56px;animation-delay:-.8s}.lds-grid div:nth-child(4){top:32px;left:8px;animation-delay:-.4s}.lds-grid div:nth-child(5){top:32px;left:32px;animation-delay:-.8s}.lds-grid div:nth-child(6){top:32px;left:56px;animation-delay:-1.2s}.lds-grid div:nth-child(7){top:56px;left:8px;animation-delay:-.8s}.lds-grid div:nth-child(8){top:56px;left:32px;animation-delay:-1.2s}.lds-grid div:nth-child(9){top:56px;left:56px;animation-delay:-1.6s}@keyframes lds-grid{0%,100%{opacity:1}50%{opacity:.5}}
.centered{height: 80px;position: absolute;left: 50%;top: 50%;transform: translate(-50%, -50%);}
</style>
<div class="lds-grid centered"><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div></div>