While waiting for a larger fix of the themes, force prevent overriding of the web editor's UI CSS by themes. This is achieved by applying `!important` on all web editor UI CSS. This is a temporary fix until the themes CSS is fixed and/or the new web editor library is ready. closes odoo/odoo#31721 Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>