This commit fixes the style of the "Add a note" element in the
activities menu list. Before this commit, the background was white
because the color was hardcoded in a scss file. This is not longer
the case with this fix.
Also, the input has a transparent background to match with the
background color.
task-3208042
closesodoo/odoo#114143
X-original-commit: 5829183b57478b3316cacda931c2245b17896a63
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>