<button class="cp_button08">button</button>

.cp_button08 {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 160px;
  padding: 1em;
  cursor: pointer;
  color: #7e57c2;
  background: transparent;
  border: 1px solid #7e57c2;
  border-radius: 0.2em;
  transition: background-color 0.2s, color 0.2s, width 0.2s cubic-bezier(0.175, 0.885, 0.32, 1.275), border-radius 0.2s;
}
.cp_button08:hover {
  width: 180px;
  color: #ffffff;
  border-radius: 0.5em;
  background-color: #7e57c2;
}
.cp_button08:active {
  border-color: #5e35b1;
  background-color: #5e35b1;
}
.cp_button08:focus {
  color: #7e57c2;
  border: 1px solid #7e57c2;
}
.cp_button08:focus:hover {
  color: #ffffff;
}