Answers for "how to center div in middle of page"

css center element on screen

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

center div in middle of page

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  /* bring your own prefixes */
  transform: translate(-50%, -50%);
}

align div to center of screen

div.the-center-div {
	margin: 0 auto;
}

center a div on screen

.class{
position: realtive;
text-align: center;
top: 50%;
transform:translateY(-50%);
}

how to assign something in center inside a div

IMG.displayed {
    display: block;
    margin-left: auto;
    margin-right: auto }
...
<IMG class="displayed" src="..." alt="...">