CODE EXAMPLE FOR CSS

scroll bar on border radius element css

.outer {
  width: 150pt;
  border: 1px solid red;
  border-radius: 15pt;
  
  /* this */
  overflow: hidden;
}

.inner {
  height: 200px;
  /* and this */
  overflow-y: auto;
}
<div class="outer">
    <div class="inner">
        <!-- lots of text here -->
    </div>
</div>