Answers for "make everything in a div center"

different ways to center a div

/* Centering an element without flexbox */
.parent-element {
  position: relative;
}

.child-element {
	position: absolute;
  	left: 50%;
  	top: 50%;
  	transform: translate(-50%, -50%);
}

/* Centering an element using flexbox */
.parent-element {
	display: flex;
  	align-items: center;
  	justify-content: center;
}

how to assign something in center inside a div

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