실행 결과가 달라요

"""

import { useState } from 'react'
import reactLogo from './assets/react.svg'
import viteLogo from '/vite.svg'
import './App.css'

function App() {
  const [count, setCount] = useState(0)

  return (
    <>
    <div className="App">
      <div className='black-nav'>
        <h4>블로그임</h4>
      </div>
    </div>
    </>
  )
}

export default App
""" App.jsx

"""
.black-nav{
  display: flex;
  background:black;
  width: 100%;
  color: white;
  padding-left: 20px;
}
""" App.css