Update font size in app.py for improved readability

Increased the font size from 10px to 18px in the CSS styles to enhance the visual presentation and accessibility of the application. This change aims to further improve user experience by making text more legible.

app.py

@@ -62,7 +62,7 @@ st.markdown("""
     )
 
     div {
-        font-size: 10px;
+        font-size: 18px;
     }