* {
  box-sizing: border-box;
  margin: 0;
}

button {
  border: none;
  background-color: #fff;
  padding: 18px 30px;
  cursor: pointer;
  background-color: rgba(0, 0, 0, 0.05);
}

.line-button {
  position: relative;
}

.line-button::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: #0066ff;
  transition: width 250ms ease-out;
}

.line-button:hover::after {
  width: 100%;
}