css content overflow 2 scroll

w3school overflow scroll

  height: 300px;
  overflow: scroll;

When the attribute scroll is specified above, a scrolling box appears, regardless of whether the height exceeds the height.
stackoverflow: how-to-show-scroll-after-certain-height-but-height-should-not-be-fixed

.container{
  height: 263px;
  overflow-y: auto;
}