style: update CustomHeader and documentation hero section

- Modified the CustomHeader component to hide certain elements on smaller screens for improved responsiveness.
- Corrected the class for the hero section title in documentation to ensure proper text styling and spacing.

Author: geromegrignon

src/components/ui/CustomHeader.astro

@@ -6,9 +6,9 @@ import ThemeSelect from "@astrojs/starlight/components/ThemeSelect.astro";
 
 <nav class="flex items-center justify-between">
 <h1 class="font-[Geist] text-xl flex items-center">
-     <span>tutorials.</span>
+     <span class="hidden md:block">tutorials.</span>
     <span class="text-[#02BCFF]">angular.</span>
-    <span>courses</span>
+    <span class="hidden md:block">courses</span>
 </h1>
 <Search />
 <div class="flex items-center gap-6">

src/content/docs/index.mdx

@@ -6,7 +6,7 @@ hero:
   title: |
     <span class="font-[BungeeHairline]">Start learning</span>
     <span
-      class="text-7xluppercase font-bold font-[BungeeInline]">
+      class="text-7xl uppercase font-bold font-[BungeeInline]">
       Angular
     </span>
   tagline: Discover Angular with our community tutorial