Center Everything

Center an element vertically and horizontally with grid:

.element {
  display: grid;
  place-items: center;
}

Center an element horizontally and vertically using flexbox:

.parent {
  display: flex;
  align-items: center;
  justify-content: center;
}

Center a block element horizontally – common for inline elements set as block (ex, img) for this purpose:

.image {
  display: block;
  margin: auto;
}

Center inline (text, span, heading, etc…) elements horizontally:

.txt {
  text-align: center;
}

Horizontally enter an element relative to the viewport:

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

Horizontally center absolutely positioned element: *Remember to set parent to position:relative.

.child{
position: absolute;
left: 50%;
transform: translateX(50%);
}

Horizontally center absolutely-positioned element within another absolutely-positioned element:

.child{
left: 0;
right: 0;
margin: auto;
}

Horizontally center an inline or inline-block element (common use-case is pseudo elements):

.element:before{
content: '';

}