use styled-jsx in PageContainer

src/components/PageContainer.tsx

@@ -5,13 +5,17 @@ import { Theme } from "../theme/Theme";
 const PageContainer: FunctionComponent<{ theme: Theme }> = (props) => {
     return (
         <div style={{
-            display: "flex",
-            flexDirection: "column",
-            alignItems: "center",
             background: props.theme?.background,
-            flex: "1",
-            minHeight: "400px"
         }}>
+            <style jsx>{`
+                div {
+                    display: flex;
+                    flex-direction: column;
+                    align-items: center;
+                    flex: 1;
+                    min-height: 400px;
+                }
+            `}</style>
             {props.children}
         </div>
     );