how to add css to Link reac router dom code example

Example 1: react link underline

<Link to="first" style={{ textDecoration: 'none' }}>
  <MenuItem style={{ paddingLeft: 13 }}>Team 1</MenuItem>
</Link>

Example 2: how to decurate react router link css

#Nav_menu {
  display: flex;
  flex-direction: row;
  width: 100%;
  height: 100%;
  list-style-type: none;
  margin: 0;
  padding: 0;
}

.Nav_link:link {
  color: #fff;
  font-size: 1.6rem;
  line-height: 1.6rem;
  text-decoration: none;
}
.Nav_link:visited {
  color: #fff;
}
.Nav_link:hover {
  color: yellow;
}
.Nav_link:active {
  color: teal;
}

.activeRoute {
  background-color: yellow;
  border-bottom: 0.4rem solid teal;
  cursor: not-allowed;
}