[FIX] website: fix the position of the ripple effect

Before this commit, the ripple effect did not work when a button was not
in the same location/size when clicked compared to its position/size
when the page was loaded. (e.g. after scrolling the page)

task-2686370

closes odoo/odoo#80611

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>