### Steps to reproduce

1. Login as an admin

2. Go to Administration > Design

3. Change Begin of the insertionthemeEnd of the insertion Begin of the deletion display modeEnd of the deletion with the 'Color theme' drop down


### What is the buggy behavior?

* Begin of the insertionThe names of the themes are confusing, since we use "Light" and "Dark" for the names of both themes (under "Design") and modes (personal settings).

* OpenProjectEnd of the insertion Begin of the deletion DropdownEnd of the deletion is Begin of the insertionthe default theme.

End of the insertion Begin of the deletion misleading

End of the deletion * OpenProject Light is Begin of the insertiona lighter-coloured theme.

End of the insertion Begin of the deletion the high contrast mode

End of the deletion * OpenProject Dark is Begin of the insertiona darker-coloured theme.


### Important context

Themes are modes are two separate things. 

Modes are "light/dark/high-contrast" versions of a theme. Essentially what happens is thatEnd of the insertion the Begin of the insertionsame set of colours are shifted in interesting ways to make things dark, or high-contrast. But theEnd of the insertion Begin of the deletion BIMEnd of the deletion theme Begin of the insertionis still the same.

Since we didn't have modes in the past, presumably "themes" were named as Dark/Light since this was the only way to get something close to a dark mode. 

Currently, we only have multiple modes for the basic "OpenProject" theme. But admittedly, this is all confusing.

End of the insertion Begin of the deletion


End of the deletion ### What is the expected behavior?

Begin of the insertion* Under Administration → Design, renameEnd of the insertion Begin of the deletion 1. Modes haveEnd of the deletion the Begin of the insertionthemesEnd of the insertion Begin of the deletion same name and themeEnd of the deletion as Begin of the insertionsuch:

* "OpenProject" → "OpenProject default"

* "OpenProject Light" → "OpenProject Grey"

* "OpenProject Dark" → "OpenProject Navy Blue"


End of the insertion Begin of the deletion the ones in the My Account section, see below 
<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/199053/content">


End of the deletion ### Screenshots and other files

Begin of the insertion**Current mode selection options (personal settings):**

End of the insertion <img class="op-uc-image op-uc-image_inline" Begin of the insertionsrc="/api/v3/attachments/199053/content">

**Current colour theme selection (admin settings):**<img class="op-uc-image op-uc-image_inline"End of the insertion src="/api/v3/attachments/199051/content"> Begin of the insertion

**&quot;OpenProject Dark&quot; theme enabled in admin settings:**End of the insertion

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/199050/content">

### Environment information

**OpenProject version**

_dev_

**Browser**

* [ ] Chrome
* [x] Firefox
* [ ] Safari
* [ ] Mobile Safari
* [ ] Other (please specify)

**Operating System**

* [x] Windows
* [ ] Mac OS X
* [ ] Mobile iOS
* [ ] Mobile Android
* [ ] Linux (please specify distro)
* [ ] Chrome OS
* [ ] Other (please specify)