[4.4] Cassiopeia back to top

[brianteeman]

Pull Request for Issue #42312 .

Summary of Changes

When enabled the back to top button should be visible as soon as you have scrolled

Testing Instructions

Apply pr and run npm build:css or use a prebuilt package in this pr

In the cassiopeia template style enable the back to top button

In the front end test on a short page (no scrolling possible) and a long page (with scrolling)

Expected result BEFORE applying this Pull Request

back to top button is not present on the short page
back to top button is visible on the long page only when you have reached the very bottom of the page

Expected result AFTER applying this Pull Request

back to top button is not present on the short page
back to top button is visible on the long page as soon as you start scrolling and disapears as soon as you scroll nack to the top

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[Quy]

I have tested this item ✅ successfully on b0e9dad

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[viocassel]

I have tested this item ✅ successfully on b0e9dad

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43057.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43057.}

[laoneo]

Thanks!