I'm fairly new to javascript and react, but I'm diving in and creating my first react app.

I'm tying to modify the amount of "gridTemplateRows" that display on my screen via a variable and modify it with a new numbers based on the results from the list (I've hard coded this as a 6 right now), however I'm using CSS Modules and i can't seem to get the grid to change its row count and display properly.

Component Code

import classes from "./TimeSlot.module.scss";
import AvailabilityCalendarData from "../../../../../FakeDB/AvailabilityCalendarData";

function TimeSlot() {
  const addTimeSlot = () => {
    document.getElementsByClassName(
      `${classes.time_interval}`
    ).styles.gridTemplateRows = "repeat(6, 1fr)";
  };

  const timeSlotRow = AvailabilityCalendarData.map((timeSlot) => (
    <div key={timeSlot.id}>{timeSlot.startTime}</div>
  ));

  return (
    <div className={classes.time_interval} onLoad={addTimeSlot()}>
      {timeSlotRow}
    </div>
  );
}

export default TimeSlot;

CSS

.time_interval {
  grid-area: time;
  display: grid;
  grid-template-rows: repeat(17, 1fr);
  font-size: 14px;
  & > div {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    box-shadow: inset 0 1px 0 0 #eceff1;
  }
}