Answers for "center item flexbox"

css flex center

display: flex;
align-items: center;
justify-content: center;

centering with flexbox

/* HORIZONTAL */
justify-content: center;

/* VERTICAL */
align-items: center;

center flex

.flex-container {
  display: flex;
  height: 300px;
  justify-content: 
  center;
  align-items: center;
}