feat: set up global styles for font

src/components/DocsLayout/index.tsx

@@ -8,6 +8,7 @@
 import React, { PropsWithChildren } from "react"
 import { useStaticQuery, graphql } from "gatsby"
 
+import { GlobalStyles } from "../../globalStyles"
 import { DocsSidebar } from "../DocsSidebar"
 import { Footer } from "../Footer"
 import * as SC from "./styles"
@@ -25,6 +26,7 @@ export function DocsLayout({ children }: PropsWithChildren<{}>) {
 
   return (
     <div>
+      <GlobalStyles />
       <SC.Main>
         <DocsSidebar />
         <SC.MainContent>

src/components/Layout/index.tsx

@@ -11,6 +11,7 @@ import { useStaticQuery, graphql } from "gatsby"
 import { Container } from "../Container"
 import { Footer } from "../Footer"
 import { Header } from "../Header"
+import { GlobalStyles } from "../../globalStyles"
 import "./layout.scss"
 import * as SC from "./styles"
 import Scrollbar from "react-perfect-scrollbar"
@@ -29,6 +30,7 @@ export function Layout({ children }: PropsWithChildren<{}>) {
 
   return (
     <Scrollbar>
+      <GlobalStyles />
       <SC.Main>
         <Header />
         <SC.MainContent>

src/globalStyles.tsx

@@ -0,0 +1,12 @@
+import { createGlobalStyle } from "styled-components"
+
+export const GlobalStyles = createGlobalStyle`
+  html {
+    font-family: Oxygen;
+  }
+
+  body {
+    font-size: 18px;
+    line-height: 25px;
+  }
+`