Homepage update (#2663)

# Description

Please provide a summary of the changes, including relevant motivation
and context.

Closes #(issue_number)

## Checklist

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have performed a self-review of my own code
- [ ] I have attached images of the change if it is UI based
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [ ] My changes generate no new warnings
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

---------

Co-authored-by: Reece Browne <reece@stirling.pdf>

src/main/resources/static/css/theme/theme.dark.css

@@ -58,6 +58,8 @@
     --md-nav-on-section-color-organize: rgba(28, 27, 31, var(--md-nav-on-section-color-opacity));
     --md-nav-section-color-convert: rgba(25, 177, 212, var(--md-nav-section-color-opacity));
     --md-nav-on-section-color-convert: rgba(28, 27, 31, var(--md-nav-on-section-color-opacity));
+    --md-nav-section-color-convertto: rgba(104, 220, 149, var(--md-nav-section-color-opacity));
+    --md-nav-on-section-color-convertto: rgba(28, 27, 31, var(--md-nav-on-section-color-opacity));
     --md-nav-section-color-security: rgba(255, 120, 146, var(--md-nav-section-color-opacity));
     --md-nav-on-section-color-security: rgba(28, 27, 31, var(--md-nav-on-section-color-opacity));
     --md-nav-section-color-other: rgba(72, 189, 84, var(--md-nav-section-color-opacity));
@@ -70,4 +72,8 @@
     --md-nav-on-section-color-word: rgba(28, 27, 31, var(--md-nav-on-section-color-opacity));
     --md-nav-section-color-ppt: rgba(255, 128, 0, var(--md-nav-section-color-opacity));
     --md-nav-on-section-color-ppt: rgba(28, 27, 31, var(--md-nav-on-section-color-opacity));
-}
+    --md-nav-color-on-seperator: rgb(24 28 34);
+    --md-nav-background: rgb(15 20 26);
+    --favourite-add: #9ed18c;
+    --favourite-remove: palevioletred;
+}