refactor: center banner notice text

src/components/AppBar/AppBar.tsx

@@ -132,8 +132,10 @@ export const AppBar = () => {
         <div className={styles.banner}>
           <Container>
             <div className={styles.bannerInner}>
+              <p className={styles.bannerText}>
                 SIGit is currently Alpha software (available for internal
                 testing), use at your own risk!
+              </p>
               <Button
                 aria-label={`close banner`}
                 variant="text"

src/components/AppBar/style.module.scss

@@ -67,3 +67,9 @@
     }
   }
 }
+
+.bannerText {
+  margin-left: 54px;
+  flex-grow: 1;
+  text-align: center;
+}