Problemas com o background-color

Fala Lucas! Vc colocou esse código css dentro do arquivo index.css? Se sim, confirma se o arquivo está na raíz do src. A resposta sendo novamente positiva, o index.css precisa está sendo chamado dentro do index.tsx, realizando um import da seguinte forma => import "./index.css";

Segue o arquivo index.css

html,
body,
div,
span,
applet,
object,
iframe,
h1,
h2,
h3,
h4,
h5,
h6,
p,
blockquote,
pre,
a,
abbr,
acronym,
address,
big,
cite,
code,
del,
dfn,
em,
img,
ins,
kbd,
q,
s,
samp,
small,
strike,
strong,
sub,
sup,
tt,
var,
b,
u,
i,
center,
dl,
dt,
dd,
ol,
ul,
li,
fieldset,
form,
label,
legend,
table,
caption,
tbody,
tfoot,
thead,
tr,
th,
td,
article,
aside,
canvas,
details,
embed,
figure,
figcaption,
footer,
header,
hgroup,
menu,
nav,
output,
ruby,
section,
summary,
time,
mark,
audio,
video {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
}
/* HTML5 display-role reset for older browsers */
article,
aside,
details,
figcaption,
figure,
footer,
header,
hgroup,
menu,
nav,
section {
  display: block;
}
body {
  line-height: 1;
}
ol,
ul {
  list-style: none;
}
blockquote,
q {
  quotes: none;
}
blockquote:before,
blockquote:after,
q:before,
q:after {
  content: "";
  content: none;
}
table {
  border-collapse: collapse;
  border-spacing: 0;
}

input {
  font-family: inherit;
  font-size: inherit;
  font-weight: inherit;
  color: inherit;
}

button {
  border: unset;
  background-color: unset;
  font-family: inherit;
  font-size: inherit;
  font-weight: inherit;
  color: inherit;
}

@import url("https://fonts.googleapis.com/css2?family=Manjari&display=swap");

body {
  display: flex;
  justify-content: center;
  font-family: "Manjari", sans-serif;
  color: #f0f0f0;
  background-color: #4c4c4c;
  height: 100%;
  width: 100%;
  padding: 16px;
  box-sizing: border-box;
}

#root {
  width: 100%;
}

::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: unset;
}

::-webkit-scrollbar-thumb {
  border-radius: 4px;
  background: #888;
}

::-webkit-scrollbar-thumb:hover {
  background: #555;
}

Obrigado!!! Resolveu aqui foi um problema de importação eu não tinha importado o css dentro do index,tsx