website: add GitHub button to landing page

website/src/pages/index.js

@@ -29,6 +29,16 @@ function Home() {
               Get Started  →
             </Link>
           </div>
+          <div className="margin-top--lg">
+            <iframe
+              src="https://ghbtns.com/github-btn.html?user=yangshun&amp;repo=tech-interview-handbook&amp;type=star&amp;count=true&amp;size=large"
+              frameBorder={0}
+              scrolling={0}
+              width={160}
+              height={30}
+              title="GitHub Stars"
+            />
+          </div>
         </div>
       </header>
       <main>

website/src/pages/styles.module.css

@@ -6,7 +6,7 @@
 }
 
 .heroBannerLogo {
-  max-width: 240px;
+  max-width: 300px;
 }
 
 @media screen and (max-width: 966px) {