How to set css or style for a special tab-button?

Ionic Framework ionic-v3
1

in tabs , how can i set css/style for a special tab-button??

i only found tab-button id in html

<a class="tab-button has-title has-icon disable-hover" href="#" role="tab" 
id="tab-0-1" aria-controls="tabpanel-0-1" aria-selected="false">
    <!--template bindings={}-->
    <ion-icon class="tab-button-icon ion-md-unlock" role="img" aria-label="unlock"></ion-icon>
    <!--template bindings={}-->
    <span class="tab-button-text">contact</span>
    <!--template bindings={}-->
    <ion-button-effect>
    </ion-button-effect>
</a>

I can only write css by tab-button id???