UI refinements (#2859)

## Description:

UI Refinements requested by @evanpelle  check https://ui.openfront.dev

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

w.o.n

src/client/components/FluentSlider.ts

@@ -106,7 +106,7 @@ export class FluentSlider extends LitElement {
                 .min=${this.min}
                 .max=${this.max}
                 .valueAsNumber=${this.value}
-                class="w-[60px] bg-black/40 text-white border border-white/20 text-center rounded text-sm p-1 leading-none font-bold font-inherit mt-1 focus:outline-none focus:border-blue-500"
+                class="w-[60px] bg-black/60 text-white border border-white/20 text-center rounded text-sm p-1 leading-none font-bold font-inherit mt-1 focus:outline-none focus:border-blue-500"
                 @input=${this.handleNumberInput}
                 @blur=${() => {
                   this.isEditing = false;