<div class="wrapper">
  <img src="https://dic.academic.ru/pictures/wiki/files/78/Naval_Ensign_of_the_United_Kingdom.svg">
</div>

body {
  margin: 0;
}

.wrapper {
  position: relative;  
  overflow: hidden;
  
  min-height: 100vh;
}

img {
  position: absolute;
  top: 0;
  left: 50%;
  
  transform: translateX(-50%);
}