// :::ISSUE:::
// class active is ALWAYS assigned to homepage which means TWO active elements
<NavLink to="/mywebpage" exact="true">
homepage
</NavLink>
<NavLink to="/mywebpage/contact">
contact
</NavLink>
// :::SOLUTION:::
// Just add "/" in first line, at the end: to="/mywebpage" -> to="/mywebpage/"
// also remember to have exact="true" like in example above