<button>Read More</button>

html, body {
  background: #000; 
}

button{
  font-family: 'Arial Black';
  border-radius: 25px;
  padding: 15px;
  boz-sizing: border-box;
  border: 1px solid #222;
  background-color: #101010;
  position: relative;
  padding-right: 55px;
  color: #fff;
}
button:after{
  content: ">";
  font-family: "Courier New";
  display: block;
  width: 40px;
  position: absolute;
  border: inherit;
  border-left: none;
  border-radius: 0 25px 25px 0;
  border-color: #2db2fa;
  background-color: #16313f;
  top: 0;
  bottom: 0;
  right: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}