fix(style): dropdown not visible on windows dark theme. (#739)

# Motivation

The select options of the dropdown are not visible on Windows with the
dark-theme (reproduced on W10 Chrome / Firefox / Edge).

<img width="960" height="540" alt="chrome"
src="https://github.com/user-attachments/assets/59555e14-dc2c-47e1-94e1-e5b2ff1a81a7"
/>
<img width="960" height="540" alt="edge"
src="https://github.com/user-attachments/assets/b6cdb38a-9efc-4258-9133-071d4f947d7c"
/>

# Changes

Adjust the styling to make the options visible on windows.

<img width="960" height="540" alt="fix"
src="https://github.com/user-attachments/assets/89d58960-7481-4aeb-b960-16bea900c6e5"
/>

Author: 0xFFrancesco

src/lib/components/Dropdown.svelte

@@ -62,7 +62,7 @@
 
     select {
       width: 100%;
-      background: transparent;
+      background: var(--input-background);
       border: none;
 
       --select-padding-inner-top-bottom: var(