AI solution for CSS coding question on BFE.dev
1. center an element vertically

One way to center the inner div vertically is to use flexbox. You can set the outer div to display flex and then use the align-items property to center the inner div vertically.

.outer {
  display: flex;
  align-items: center;
  justify-content: center; /* Optional: Horizontal centering */
  height: 100vh; /* Adjust this to fit your layout */
  background-color: #efefef;
}

.inner {
  width: 100px;
  height: 100px;
  background-color: #f44336;
}

The align-items: center property will center the inner div vertically in the outer div. If you want to also horizontally center it, you can add justify-content: center to the outer div.

Note that we also set the height of the outer div to 100vh to make it take up the full height of the viewport. You may need to adjust this value based on your layout.