CSHARP

#grid

#grid {
  display: grid;
  width: 80%;
  grid-template-columns: 50px 1fr;
}

#areaA {
  background-color: lime;
}

#areaB {
  background-color: yellow;
}

#grid

#grid {
  display: grid;
  width: 100%;
  grid-template-columns: 50px 1fr;
}

#areaA {
  background-color: lime;
}

#areaB {
  background-color: yellow;
}

grid

  <Grid container spacing={4}>
      <Grid item md={4}>
        <div style={{ backgroundColor: "red" }}>1</div>
      </Grid>
      <Grid item md={4}>
        <div style={{ backgroundColor: "red" }}>1</div>
      </Grid>
      <Grid item md={4}>
        <div style={{ backgroundColor: "red" }}>1</div>
      </Grid>
    </Grid>

grid

 <Grid container spacing={2}>
              <Grid item lg={6} md={6} sm={12} xs={12}>
                sd
              </Grid>
              <Grid item lg={6} md={6} sm={12} xs={12}>
                sd
              </Grid>
            </Grid>