Progress new Mantid webpage

[DanielMurphy22]

Describe the outcome that is desired. A new mantid webpage has been designed and started. It will replace the current Mantid wiki pages but not the user or dev docs. This issue is to progress and hopefully roll out the new website!

Describe any solutions you are considering

• See the open PR and issues here: https://github.com/mantidproject/www.mantidproject.org
• Discuss with @martyngigg before starting!

[martyngigg]

Discussing with the TWG we agreed we'd like to release this with 6.4

[martyngigg]

A preview is at https://mantidproject.github.io/www.mantidproject.org/

[DanielMurphy22]

A review of the preview:

• It would be nice if we could detect darkmode and use: https://github.com/mantidproject/mantid/blob/main/images/Mantid_Logo_Transparent_for_dark_backgrounds.png which is an image we already have. Or a quicker solution is to always use a logo with a white background which I've made here:
• Can we align the title names to the pages they link to? : Develop -> Developer Documentation :white_check_mark: (also good Forums, Release Notes, Contact Us) :white_check_mark: User Docs -> Mantid :x: (rename mantid docs page to User Docs) Tutorials -> Training :x: (rename Training page in mantid docs to Tutorials) Downloads -> Installation :x: (rename new internal page to Downloads)

[martyngigg]

The new page is now live at https://mantidproject.org.