App.js and App.css code

app.js

///////////////// App.js
class App extends Component {
  render() {
    return (
      <div className="App">
          <div style={{flex:1, minWidth:300, minHeight:300, backgroundColor:'green'}}>
              <div className="imageConatiner">
                <div className="imageDiv"/>
              </div>
          </div>
          <div style={{flex:1, minWidth:300, minHeight:300, justifyContent:'center', backgroundColor:'red'}}>
              <div style={{backgroundColor:'yellow', width:200}}/>
          </div>
          <div style={{flex:1, minWidth:300, minHeight:300, justifyContent:'center', backgroundColor:'yellow'}}>
              <div style={{backgroundColor:'yellow', width:200}}/>
          </div>
          <div style={{flex:1, minWidth:300, minHeight:300, justifyContent:'center', backgroundColor:'blue'}}>
              <div style={{backgroundColor:'yellow', width:200}}/>
          </div>
          <div style={{flex:1, minWidth:300, minHeight:300, justifyContent:'center', backgroundColor:'pink'}}>
              <div style={{backgroundColor:'yellow', width:200}}/>
          </div>
          <div style={{flex:1, minWidth:300, minHeight:300, justifyContent:'center', backgroundColor:'orange'}}>
              <div style={{backgroundColor:'yellow', width:200}}/>
          </div>
          <div style={{flex:1, minWidth:300, minHeight:300, justifyContent:'center', backgroundColor:'purple'}}>
              <div style={{backgroundColor:'yellow', width:200}}/>
          </div>
          <div style={{flex:1, minWidth:300, minHeight:300, justifyContent:'center', backgroundColor:'black'}}>
              <div style={{backgroundColor:'yellow', width:200}}/>
          </div>
      </div>
    );
  }
}

////////////////////////App.css
.App {
  display: flex;
  background: red;
  /*height: 400px;*/
  flex-wrap: wrap;
  justify-content: center;
}

.imageConatiner {
  height: 100%;
  padding: 10%;
  justify-content: center;
  align-items: center;
}

.imageDiv {
  height: 100%;
  background: greenyellow;
}