JSFiddle - React, Tailwind, and code Playground

HTML

<button class="btn">Dropdown</button>

CSS

.btn {
  border: none;
  font-size: 15px;
  font-weight: normal;
  line-height: 1.4;
  border-radius: 4px;
  padding: 10px 15px;
  -webkit-font-smoothing: subpixel-antialiased;
  -webkit-transition: border .25s linear, color .25s linear, background-color .25s linear;
  transition: border .25s linear, color .25s linear, background-color .25s linear;
}
.btn:hover,
.btn:focus {
  outline: none;
  color: #ffffff;
   -webkit-border-radius: 30px;
-moz-border-radius: 30px;
border-radius: 30px; 
}