Slack clone header component

Header.css

.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 0;
  color: white;
  background-color: #340e36;
}

.header .MuiSvgIcon-root {
  opacity: 0.6;
}

.header__left {
  flex: 0.3;
  display: flex;
  align-items: center;
  margin-left: 20px;
}

.header__left > .MuiSvgIcon-root {
  margin-left: auto;
  margin-right: 20px;
}

.header__middle {
  flex: 0.4;
  background-color: #421f44;
  text-align: center;
  display: flex;
  padding: 0 50px;
  color: gray;
  border: 1px solid gray;
  border-radius: 6px;
}

.header__middle > input {
  background-color: transparent;
  border: none;
  color: white;
  text-align: center;
  min-width: 35vw;
}

.header__middle > input:focus {
  outline: none;
}

.header__right {
  flex: 0.3;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin: 0 20px;
}

.header__right .MuiAvatar-root {
  border-radius: 20%;
  width: 30px;
  height: 30px;
  cursor: pointer;
}

Header.js

import './Header.css'
import { Avatar } from '@material-ui/core'
import AccessTimeIcon from '@material-ui/icons/AccessTime'
import SearchIcon from '@material-ui/icons/Search'
import HelpOutlineIcon from '@material-ui/icons/HelpOutline'
import { useState, useEffect } from 'react'
import { useHistory } from 'react-router-dom'

function Header() {
  const history = useHistory()
  const [user, setUser] = useState(null)

  const moveToAcc = () => {
    const user = JSON.parse(localStorage.getItem('user'))
    history.push(`/users/${user.uid}`)
  }

  useEffect(() => {
    const data = localStorage.getItem('user')
    setUser(JSON.parse(data))
  }, [])

  return (
    <div className="header">
      <div className="header__left">
        <AccessTimeIcon />
      </div>
      <div className="header__middle">
        <SearchIcon />
        <input placeholder="Search tutorial-daltonic" />
      </div>
      <div className="header__right">
        <HelpOutlineIcon />
        <Avatar
          className="header__avatar"
          src={user?.photoURL}
          alt={user?.displayName}
          onClick={moveToAcc}
        />
      </div>
    </div>
  )
}

export default Header