mira, tengo esto:

import React, { useState } from "react";
import Contact from "./components/contact/Contact";
import Experience from "./components/experience/Experience";
import Footer from "./components/footer/Footer";
import Header from "./components/header/Header";
import Intro from "./components/intro/Intro";
import Portfolio from "./components/portfolio/Portfolio";
import Testimonials from "./components/testimonials/Testimonials";
import Topbar from "./components/topbar/Topbar";

const App = () => {
  const [language, setLanguage] = useState("en");

  const handleLanguageChange = (lang) => {
    setLanguage(lang);
  };

  return (
    <>
      <Header language={language} onLanguageChange={handleLanguageChange} />
      <Topbar language={language} />
      <Intro language={language} />
      <Experience language={language} />
      <Portfolio language={language} />
      <Testimonials language={language} />
      <Contact language={language} />
      <Footer language={language} />
    </>
  );
};

export default App;

el css es este:

@import url("https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600&family=Roboto:wght@100;300;700;900&display=swap");

* {
  margin: 0;
  padding: 0;
  border: 0;
  outline: 0;
  box-sizing: border-box;
  list-style: none;
  text-decoration: none;
}

:root {
  --color-bg: #1f1f38;
  --color-bg-variant: #2c2c6c;
  --color-primary: #4db5ff;
  --color-primary-variant: rgba(77, 181, 255, 0.4);
  --color-white: #fff;
  --color-light: rgba(255, 255, 255, 0.6);

  --transition: all 400ms ease;

  --container-width-lg: 75%;
  --container-width-md: 86%;
  --container-width-sm: 90%;
}

html {
  scroll-behavior: smooth;
}

::-webkit-scrollbar {
  display: none;
}

body {
  font-family: "Poppins", sans-serif;
  background-color: var(--color-bg);
  color: var(--color-white);
  line-height: 1.7;
  background-image: url(../assets/texture.jpg);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

.container {
  width: var(--container-width-lg);
  margin: 0 auto;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 500;
}

h1 {
  font-size: 2.5rem;
}

section {
  margin-top: 8rem;
}

section > h2,
section > h5 {
  color: var(--color-light);
  text-align: center;
}

section > h2 {
  color: var(--color-primary);
  margin-bottom: 3rem;
}

.text-light {
  color: var(--color-primary);
}

a {
  transition: var(--transition);
  color: var(--color-primary);
}

a:hover {
  color: var(--color-white);
}

.btn {
  width: max-content;
  display: inline-block;
  color: var(--color-primary);
  padding: 0.75rem 1.2rem;
  border-radius: 0.4rem;
  cursor: pointer;
  border: 1px solid var(--color-primary);
  transition: var(--transition);
}

.btn:hover {
  background-color: var(--color-white);
  color: var(--color-bg);
  border-color: transparent;
}

.btn-primary {
  background-color: var(--color-primary);
  color: var(--color-bg);
}

img {
  display: block;
  width: 100%;
  object-fit: cover;
}

@media screen and (max-width: 1024px) {
  .container {
    width: var(--container-width-md);
  }

  section {
    margin-top: 6rem;
  }
}

@media screen and (max-width: 600px) {
  .container {
    width: var(--container-width-sm);
  }

  section > h2 {
    margin-bottom: 2rem;
  }
}


necesito que el background de mi app sea como especie de una textura, una imagen, esta iamgen, que se vea mas oscurita:  https://i.pinimg.com/originals/20/99/f2/2099f2dda704cb708fe20347afb964ba.jpg