<Styled @bind-Classname="@hover">
    label: hover-example;
    padding: 32px;
    background-color: hotpink;
    font-size: 24px;
    border-radius: 4px;
</Styled>

<Styled Classname="@hover" PseudoClass="PseudoClasses.Hover">
    color: @color;
</Styled>

<div class="@hover">
    Hover to change color.
</div>

@code {
    private string hover;
    private string color = "white";
}