Answers for "how to make all element center in css"

center a div in css

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

center div horizontally and vertically

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

how to center a div element

/*ADD MARGIN auto to left and right*/
.box1{
    width:80%;
    margin:0 auto;
}