<div class="container">
  <div class="content">
    <a href="https://qna.habr.com/q/721165?e=8683133" target="_blank" class="link">Какая-то ссылка</a>
  </div>
</div>

body, html {
  width: 100%;
  height: 100%;
}

.content {
  position: relative;  
}

.link {
  font-wight: bold;
  font-size: 30px;
  padding: 10px 20px;
  border: 1px solid red;
  background: #ccc;
}

.container {
  position: relative;
  width: 100%;
  height: 100%;
  
  background: linear-gradient(to bottom,  rgba(53,170,195,1) 0%,rgba(113,228,212,1) 100%);
  
  &::before {
    user-select: none;
    content: '';
    position: absolute;
    margin: auto;
    width: 100%;
    height: 100%;
    top: 0; left: 0; right: 0; bottom: 0;
    
    background: url(https://friend.ua/image/catalog/pages/sites/header.png);
  }
}