Perfectly Center Any Element with CSS Flexbox

.container {
  display: flex;
  justify-content: center; /* Centers horizontally */
  align-items: center;    /* Centers vertically */
  min-height: 100vh;      /* Example: takes full viewport height */
  border: 1px dashed #ccc;
}

.centered-item {
  padding: 20px;
  background-color: lightblue;
}

How it works: This snippet demonstrates how to perfectly center any child element within its flex container. By setting `display: flex` on the parent, `justify-content: center` centers items along the main axis (horizontally by default), and `align-items: center` centers them along the cross axis (vertically by default). This is a highly robust and flexible centering solution.