membuat tombol wa melayang

Assalamualaikum,.. 
 
berikut contohnya 
 
<a href="https://wa.me/6281234567890" target="_blank" id="wa-float-btn">
  <img src="https://upload.wikimedia.org/wikipedia/commons/6/6b/WhatsApp.svg" alt="WhatsApp" style="width:48px;height:48px;">
</a>
<style>
  #wa-float-btn {
    position: fixed;
    width: 60px;
    height: 60px;
    bottom: 30px;
    right: 30px;
    z-index: 1000;
    background: #25d366;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    transition: box-shadow 0.2s;
  }
  #wa-float-btn:hover {
    box-shadow: 0 4px 16px rgba(0,0,0,0.3);
    background: #128c7e;
  }
  #wa-float-btn img {
    width: 32px;
    height: 32px;
  }
</style>