React-Bootstrap causing margins on left and right side

I tested your code with a clean react app. The previous suggestions were wrong. You need to set Grid components padding-left and padding-right to 0.

UPDATE: Just setting Grid is not enough. Also need to set margins to 0 of Row and paddings to 0 of Col.

You can achieve this by 3 ways.

1. Way: Add inline style for Grid, Row and Col

<Grid fluid style={{ paddingLeft: 0, paddingRight: 0 }}>
    <Row style={{ margin-left: 0, margin-right: 0 }}>
        <Col style={{ padding-left: 0, padding-right: 0 }}>
            ...
        </Col>
    </Row>
</Grid>

OR

const styles = {
    grid: {
        paddingLeft: 0,
        paddingRight: 0
    },
    row: {
        marginLeft: 0,
        marginRight: 0
    },
    col: {
        paddingLeft: 0,
        paddingRight: 0
    }
};
<Grid fluid style={styles.grid}>
    <Row style={styles.row}>
        <Col style={styles.col}>
            ...
        </Col>
    </Row>
</Grid>

2. WAY: Add a custom class name

//App.css
div.noPadding {
    padding-left: 0;
    padding-right: 0;
}

div.noMargin {
    margin-left: 0;
    margin-right: 0;
}

//App.js
import '/path/to/your/App.css';

render() {
    return (
        <Grid fluid className="noPadding">
            <Row className="noMargin">
                <Col className="noPadding">
                    ...
                </Col>
            </Row>
        </Grid>
    )
}

3. WAY You can globally change Grid, Row and Col components behaviour by overriding components className

//App.css

div.container-fluid {
    padding-left: 0;
    padding-right: 0;
}

div.row {
    margin-right: 0px;
    margin-left: 0px
}

div.col-lg-1,div.col-lg-10,div.col-lg-11,div.col-lg-12,div.col-lg-2,div.col-lg-3,div.col-lg-4,div.col-lg-5,div.col-lg-6,div.col-lg-7,div.col-lg-8,div.col-lg-9,
div.col-md-1,div.col-md-10,div.col-md-11,div.col-md-12,div.col-md-2,div.col-md-3,div.col-md-4,div.col-md-5,div.col-md-6,div.col-md-7,div.col-md-8,div.col-md-9,
div.col-sm-1,div.col-sm-10,div.col-sm-11,div.col-sm-12,div.col-sm-2,div.col-sm-3,div.col-sm-4,div.col-sm-5,div.col-sm-6,div.col-sm-7,div.col-sm-8,div.col-sm-9,
div.col-xs-1,div.col-xs-10,div.col-xs-11,div.col-xs-12,div.col-xs-2,div.col-xs-3,div.col-xs-4,div.col-xs-5,div.col-xs-6,div.col-xs-7,div.col-xs-8,div.col-xs-9 {
    padding-left: 0;
    padding-right: 0;
}

I used react-bootstrap with next.js. I came up with short solution:

<Container fluid className="p-0">
    ...
</Container>

Comment. bootstrap's css was imported in my _App.js

import 'bootstrap/dist/css/bootstrap.min.css';