Why is my text not centered?

Hello,

I would have liked to know that my text is not in the same container as my two slides?

Thank you !

<ion-header style="margin-top: 16vw">
</ion-header>

<ion-content>
  <ion-header collapse="condense" class="ion-no-border">
    <ion-toolbar>
      <ion-title size="large">Découvrir</ion-title>
    </ion-toolbar>
  </ion-header>
  <div id="container">
  <ion-slides [options]="slideOpts">
    <ion-slide>
      <ion-card>
        <ion-img src="https://interactive.aljazeera.com/aje/2020/know-their-names/image/background.jpg"></ion-img>
      </ion-card>
    </ion-slide>
  </ion-slides>
  <ion-row>
    <ion-col size="9">
      Spots récemments notés
    </ion-col>
    <ion-col size="3">
      voir tout
    </ion-col>
  </ion-row>
  <ion-slides [options]="slideOptsSpots">
    <ion-slide>
      <ion-card class="cardSize">
        <ion-img src="https://interactive.aljazeera.com/aje/2020/know-their-names/image/background.jpg"></ion-img>
        <ion-card-header style="text-align: left;">
          <ion-card-subtitle>Localisation</ion-card-subtitle>
          <ion-card-title>Nom skatepark</ion-card-title>
        </ion-card-header>
      </ion-card>
    </ion-slide>
    <ion-slide>
      <ion-card class="cardSize">
        <ion-img src="https://www.journaldugeek.com/content/uploads/2019/05/apex-legends.jpg"></ion-img>
        <ion-card-header style="text-align: left;">
          <ion-card-subtitle>Card Subtitle</ion-card-subtitle>
          <ion-card-title>Card Title</ion-card-title>
        </ion-card-header>
        <ion-card-content style="text-align: left;">
          Keep close to Nature's heart... and break clear away, once in awhile,
          and climb a mountain or spend a week in the woods. Wash your spirit clean.
        </ion-card-content>
      </ion-card>
    </ion-slide>
    <ion-slide>
      <ion-card class="cardSize">
        <ion-img src="https://www.journaldugeek.com/content/uploads/2019/05/apex-legends.jpg"></ion-img>
        <ion-card-header style="text-align: left;">
          <ion-card-subtitle>Card Subtitle</ion-card-subtitle>
          <ion-card-title>Card Title</ion-card-title>
        </ion-card-header>
        <ion-card-content style="text-align: left;">
          Keep close to Nature's heart... and break clear away, once in awhile,
          and climb a mountain or spend a week in the woods. Wash your spirit clean.
        </ion-card-content>
      </ion-card>
    </ion-slide>
  </ion-slides>
</div>
</ion-content>