Update BackToTop component styles for improved visibility and usability

- Adjusted positioning and dimensions of the BackToTop button for better accessibility and user experience.
- Increased right margin and button size to enhance visibility and interaction.

src/components/ui/BackToTop.astro

@@ -22,12 +22,12 @@
   .back-to-top {
     position: fixed;
     bottom: 80px; /* Increased from 30px to avoid cookie banner */
-    right: 40px; /* Increased from 30px for more margin from edge */
+    right: 16px; /* Increased from 30px for more margin from edge */
     display: flex;
     align-items: center;
     justify-content: center;
-    width: 45px;
-    height: 45px;
+    width: 54px;
+    height: 54px;
     border-radius: 50%;
     background-color: rgba(0, 0, 0, 0.2);
     color: #fff;