fix(www): Making prev and next navigation well aligned vertica… (#19233)

* Centered prev and next navigation

* use backtick instead of single quote

* add comma at the end

Author: rizqinizamil

www/src/components/prev-and-next.js

@@ -51,6 +51,8 @@ const PrevAndNext = ({ prev = null, next = null, ...props }) => {
                 [mediaQueries.md]: {
                   marginLeft: t => `-${t.space[4]}`,
                 },
+                display: `inline-flex`,
+                alignItems: `center`,
               }}
             >
               <ArrowBackIcon sx={{ verticalAlign: `sub` }} />
@@ -74,6 +76,8 @@ const PrevAndNext = ({ prev = null, next = null, ...props }) => {
                 [mediaQueries.md]: {
                   marginRight: t => `-${t.space[4]}`,
                 },
+                display: `inline-flex`,
+                alignItems: `center`,
               }}
             >
               {next.title}