Full-width primary submit button with loading state animation.
<div class="container py-4">
<div class="p-4" style="max-width:420px;margin:0 auto"><button class="btn-submit" onclick="this.classList.add('loading');setTimeout(()=>this.classList.remove('loading'),1600)"><span class="lbl">Submit</span><span class="spn"></span></button></div>
</div>