<div class="popup">
  <button class="close">
    Закрыть
    <span></span>
  </button>
  <div class="content">
    <h3>Beauty close</h3>
    <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Dolorum dolores voluptatem fuga vel quidem corporis ratione beatae odit possimus dignissimos?</p>
    <p>Nam eius blanditiis ducimus quia, praesentium soluta? Assumenda error enim amet nulla accusantium soluta dolor aliquid eum minima repellendus, quos et quia.</p>
  </div>
</div>

.popup {
  position: fixed;
  top: 0;
  left: 0;
  
  display: block;
  width: 100%;
  width: 100vw;
  max-width: 100%;
  height: 100%;
  height: 100vh;
  max-height: 100vh;
}
.close {
  position: absolute;
  right: 20px;
  top: 10px;
  
  display: block;
  width: 120px;
  height: 40px;
  padding: 0 40px 0 0;
  
  background-color: transparent;
  transition: all 0.3s ease-out;
  border: none;
  cursor: pointer;
  
  font-size: 18px;
  font-weight: bold;
  
  z-index: 1;
  
  &::before,
  &::after {
    content: '';
    
    position: absolute;
    top: 50%;
    right: -10px;
    
    display: block;
    width: 30px;
    height: 4px;
    
    transition: all 0.3s ease-out;
    
    border-radius: 2px;
    
    background-color: currentColor;
  }
  &::before {
    transform: translate(-50%, -50%) rotate(45deg);
  }
  &::after {
    transform: translate(-50%, -50%) rotate(-45deg);
  }
  
  &:hover {
    color: darkorange;
    
    &::before {
      transform: translate(-50%, -50%) rotate(-45deg);
    }
    &::after {
      transform: translate(-50%, -50%) rotate(45deg);
    }
  }
  
  span {
    position: fixed;
    top: 0;
    left: 0;
    
    display: block;
    width: 100%;
    width: 100wv;
    height: 100%;
    height: 100vh;
    
    z-index: -1;
  }
}

.content {
  position: absolute;
  top: 50px;
  left: 50%;
  
  z-index: 3;
  
  display: block;
  width: 90%;
  width: 90vw;
  height: 90%;
  height: 90vh;
  padding: 10px 15px;
  box-sizing: border-box;
  
  transform: translateX(-50%);
  
  background-color: #ccc;
}