I did search for it but nothing seems to be working for me. Also as a newbie I could not implement given solution based on the react theorems.

I have an input field inside a styled component and when i try to enter the value in the field after a keystroke the input looses the focus.

import React, { useState } from 'react';
import styled from 'styled-components';

import Button from '../../UI/Button/Button';
import './CourseInput.css';
const CourseInput = props => {
  const [enteredValue, setEnteredValue] = useState('');
  const [isValid, setIsValid] = useState(true);
  const goalInputChangeHandler = event => {
    if (event.target.value.length > 0) {
      setIsValid(true);
    }
    setEnteredValue(event.target.value);
  };
  const formSubmitHandler = event => {
    event.preventDefault();
    if (enteredValue.trim().length === 0) {
      setIsValid(false);
      return;
    }
    props.onAddGoal(enteredValue);
  };
  const FormControl = styled.div`
    margin: 0.5rem 0;
  
  & label {
    font-weight: bold;
    display: block;
    margin-bottom: 0.5rem;
    color: ${porps => props.invalid ? 'red ' : 'black'}
  } 
  & input {
    display: block;
    width: 100%;
    border: 1px solid ${props => (props.invalid ? 'red' : '#ccc')};
    background:${porps => props.invalid ? '#ffd7d7' : 'transparent'}
    font: inherit;
    line-height: 1.5rem;
    padding: 0 0.25rem;
  } 
  & input:focus {
    outline: none;
    background: #fad0ec;
    border-color: #8b005d;
  }
  `;
  return (
    <form onSubmit={formSubmitHandler} >    
      <FormControl invalid={!isValid} >
        <label >Course Goal</label>
        <input type='text' onChange={goalInputChangeHandler} key='GoalInput' />
      </FormControl>
      <Button type="submit">Add Goal</Button>
    </form>
  );
};
export default CourseInput;