Fix page banner without js

Author: naveen521kk

src/components/manim-banner.js

@@ -4,9 +4,12 @@ import "./manim-banner.scss";
 
 const ManimBanner = () => {
     const {colorMode} = React.useContext(ThemeContext);
+    if (!colorMode){
+        return <img src="banner-light.svg" className="manim-banner" />;
+    }
     if (colorMode === "dark") {
         return <img src="banner-dark.svg" className="manim-banner" />;
-    } else {
+    } else if (colorMode === "light") {
         return <img src="banner-light.svg" className="manim-banner" />;
     }
 };